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Q&A #65 with Dr. Rhonda Patrick (12/7/24)

Posted on December 10th 2024 (7 months)

Dr. Rhonda Patrick discusses _Akkermansia muciniphila_, vitamin B1's effect on blood sugar, emulsifiers in food, and electrolyte supplements.

alcohol

The Truth About Alcohol: Risks, Benefits, and Everything In-Between | Dr. Rhonda Patrick

Posted on June 27th 2024 (about 1 year)

In this episode, we’re taking a deep dive into alcohol. We’ll explore the science, misconceptions, controversies, and health effects of this widely used drug.

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Q&A #48 with Dr. Rhonda Patrick (6/3/23)

Posted on June 13th 2023 (about 2 years)

Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.

Topic Pages

  • Breast milk and breastfeeding

    Breastfeeding transfers breast milk’s live commensal bacteria and prebiotic oligosaccharides that seed and modulate the infant gut microbiome.

  • Butyrate

    Colonic anaerobic microbiota ferment non-digestible carbohydrates into butyrate, which in turn modulates microbial composition and host epigenetics.

  • Depression

    Gut dysbiosis alters microbial metabolites, immune signaling, and vagal neurotransmission, modulating neuroinflammation and neuroplasticity that promote depressive phenotypes.

  • Intestinal permeability

    Commensal microbiota metabolites regulate epithelial tight-junction expression and mucosal immune signaling, thereby dynamically modulating intestinal paracellular permeability.

  • Lactobacillus reuteri

    Lactobacillus reuteri secretes antimicrobial reuterin, alters nutrient availability, and competes for adhesion, thereby reconfiguring gut microbiome structure.

  • Polyphenols

    Gut microbiota enzymatically catabolizes dietary polyphenols into absorbable metabolites, while polyphenols reciprocally modulate microbial composition and function.

  • Toll-like receptors

    Commensal microbiome-derived MAMPs ligate epithelial and immune Toll-like receptors, modulating MyD88-dependent signaling to maintain mucosal immune homeostasis.

News & Publications

  • Common dietary emulsifiers found in processed foods can disrupt glucose regulation and alter the gut microbiota, potentially driving metabolic and immune dysfunction. www.nature.com
    Gut Microbiome Metabolism

    The additives that make processed foods creamy, smooth, and long-lasting might come with a hidden cost. A recent study in mice found that common dietary emulsifiers disrupt glucose regulation and alter the gut microbiota, potentially contributing to metabolic disorders and immune dysfunction.

    Researchers fed mice diets containing four commonly used emulsifiers: lecithin, sucrose esters, carboxymethylcellulose, and mono- and diglycerides. Then, they analyzed how the compounds affected the gut’s protective mucus barrier and microbial diversity.

    They found that sucrose esters and carboxymethylcellulose elevated the animals' blood glucose and lipids, disrupted glucose regulation, and altered gut microbiota. Similarly, mono- and diglycerides impaired glucose and lipid metabolism, but they also raised markers of inflammation and increased bacterial encroachment into the gut mucus layer, potentially impairing immune function.

    These findings suggest that dietary emulsifiers promote metabolic dysfunction by altering the gut microbiota and disrupting glucose and lipid regulation. Notably, the amounts of emulsifiers in the animals' diets represented a much higher proportion of dietary intake than what humans typically consume, as emulsifiers in processed foods are usually in smaller amounts. Still, long-term consumption could increase exposure through a diet high in processed foods containing emulsifiers.

    Emulsifiers are common in processed foods, including ice cream, baked goods, margarine, salad dressings, and sauces. They help stabilize mixtures of oil and liquids, improving texture and shelf life. Their use reflects the broader role of food additives, which enhance flavor, preserve freshness, and improve processed food products' visual and textural appeal—often at the expense of health. Learn more about the harms of processed foods in Aliquot #111: Why ultra-processed foods and their additives are harmful.

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  • Higher exposure to 'forever chemicals'—synthetic substances pervasive in our environment—is linked to decreased kidney function in young adults, potentially driven by gut bacteria and metabolite changes. www.sciencedirect.com
    Gut Microbiome Pollution

    More than 10% of people worldwide have chronic kidney disease, a debilitating condition that progressively impairs the kidneys' capacity to filter waste and excess fluid from the blood. Evidence suggests that toxic exposures increase kidney disease risk. A recent study found that higher exposure to PFAS—so-called “forever chemicals"—was linked with decreased kidney function in young adults, potentially mediated by gut bacteria and metabolite changes.

    The study involved 78 young adults at high risk for metabolic disease. Researchers measured their baseline PFAS levels, gut bacterial composition, and blood metabolite profiles. Then, they assessed the participants' kidney function.

    They found that for each incremental increase in PFAS exposure, kidney function declined by roughly 2.4%. Shifts in specific gut bacteria and their metabolites, such as lower levels of Lachnospiraceae and increased levels of metabolites, explained up to half of the association between PFAS and reduced kidney function.

    These findings suggest that PFAS contribute to kidney damage by disrupting gut health and metabolic processes. PFAS, short for per- and polyfluoroalkyl substances, are synthetic chemicals widely used in consumer products for their water- and stain-resistant properties. Microplastics often contain PFAS that can leach into the environment and accumulate in the body. Learn more about microplastics and PFAS exposure in this episode featuring Dr. Rhonda Patrick.

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  • Gut bacteria may hold the key to diagnosing and treating endometriosis. https://www.cell.com/med/fulltext/S2666-6340\(24\)00373-8
    Gut Microbiome

    Millions of women worldwide experience pelvic pain, heavy periods, and infertility due to endometriosis, a poorly understood gynecological disease. Despite the condition’s prevalence, current treatments for endometriosis provide limited relief and often require invasive diagnostic procedures. A recent study found that bacteria in the gut may be instrumental in diagnosing and treating endometriosis.

    Researchers analyzed stool samples from women with and without endometriosis to investigate links between gut bacteria and the disease. Then, they tested the potential therapeutic effects of key metabolites produced by gut bacteria using animal models.

    They identified a distinct pattern of bacteria-derived metabolites in the stool of women with endometriosis that closely resembled those found in inflammatory bowel disease. One metabolite, 4-hydroxyindole, was considerably lower in women with the condition. Notably, this compound prevented the development of endometriotic lesions and reduced pain in the animal models.

    These findings suggest that gut bacteria play a critical role in the progression of endometriosis and that 4-hydroxyindole could be a promising non-invasive diagnostic marker and therapy for the disease. Learn how gut bacteria influence many other aspects of human health in this episode featuring Dr. Eran Elinav.

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  • Children with earlier bedtimes show up to 40% more diversity in their gut microbiota, potentially indicating better overall health than late sleepers. www.tandfonline.com
    Microbiome Sleep Microbes Development

    Early bedtimes may do more than help children wake up refreshed—they might also shape the balance of bacteria in their guts. A recent study found that children who go to bed early have distinct differences in their gut microbial populations compared to those who stay up later, potentially influencing their metabolism and overall health.

    Researchers collected fecal samples from 88 healthy children between the ages of 2 and 14 and used genetic sequencing to analyze the composition of their gut microbial populations. They compared the diversity of early sleepers' gut bacteria to that of late sleepers, looking for patterns that might relate to sleep timing.

    They found that children with earlier bedtimes had more diverse gut microbial populations, a marker of healthier gut function. Both beta and alpha diversity measures (indicators of the variety and richness of bacteria species) were as much as 40% higher in early sleepers.

    These findings suggest that sleep timing may play a role in shaping gut health. Considering the links between gut health and metabolism, they offer new insights into addressing sleep-related metabolic disorders in children. Learn about the importance of establishing a healthy gut microbiota in early life in this clip featuring Dr. Eran Elinav.

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  • The absence of gut microbes limits exercise capacity and reduces glucose utilization, highlighting the surprising role of microbiota in physical endurance. www.nature.com
    Exercise Gut Microbiome Performance Microbes

    If you’re struggling with exercise performance, your gut health might be partly to blame. The gut microbiota is critical for boosting exercise performance and regulating energy metabolism. A recent study found that mice without gut microbes, known as germ-free mice, had lower exercise capacity and used oxygen and glucose less efficiently during physical activity.

    Researchers compared germ-free mice to mice with normal gut bacteria. They fed both groups a regular diet and allowed them to exercise on running wheels. They measured the animals' body composition, oxygen and carbon dioxide usage, and glucose levels to assess how the absence of gut microbes affected exercise performance and energy use.

    They found that germ-free mice gained less weight, had lower fat mass, and had lower aerobic exercise capacity than mice with normal gut bacteria. Germ-free mice also exhibited reduced glucose storage and usage, impairing their capacity to fuel physical activity. Additionally, their fat tissue adapted by breaking down more fat, making them leaner and less prone to obesity, but at the cost of reduced energy availability during physical activity.

    These findings suggest that the absence of gut bacteria limits the body’s ability to store and use glucose, adversely affecting exercise performance. They also highlight gut microbes' vital role in supporting metabolism and physical endurance. Learn more about gut microbes' effects on metabolism in this clip featuring Dr. Michael Snyder.

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  • Early exposure to a common pollutant changes the gut microbiome, potentially influencing metabolic health. ehp.niehs.nih.gov
    Microbiome Metabolism Hormones Inflammation Pollution

    Persistent organic pollutants are pervasive environmental toxicants that threaten human health. These compounds break down slowly and are often called “forever chemicals.” Surprisingly, the concern isn’t just that these chemicals affect health but rather the mechanisms by which they do so. A recent study in mice found that exposure to persistent organic pollutants altered the animals' gut microbiome composition, skewing it toward a less beneficial profile.

    Researchers exposed young mice to the persistent organic pollutant tetrachlorodibenzofuran (TCDF), a widely distributed byproduct of various chemical processes. They analyzed the animals' gut microbial composition and assessed the physiological and metabolic effects of the exposure.

    They found that mice exposed to TCDF had lower quantities of short-chain fatty acids, indole-3-lactic acid (an anti-inflammatory compound), and hunger-modulating hormones. Exposed mice also had fewer Akkermansia muciniphila, a type of bacteria that modulates metabolism.

    These findings suggest that early life exposure to persistent organic pollutants alters the gut microbiome in mice, adversely affecting metabolism. Learn about the importance of early life establishment of the gut microbiome in this episode featuring Dr. Eran Elinav.

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  • Infrequent bowel movements may increase the risk of kidney dysfunction. www.sciencedaily.com
    Gut Diet Microbiome Fiber

    How often a person has a bowel movement—influenced by what they eat or drink or other lifestyle factors—affects their gut microbiome’s overall makeup, ultimately influencing disease risk. A recent study found that infrequent bowel movements drive the accumulation of toxic metabolites that impair kidney function.

    The study involved more than 1,000 healthy adults. Researchers collected information about the participants' bowel movement frequency and lifestyles. They categorized the participants according to the frequency of their bowel movements: diarrhea, high-normal (one to three daily), low-normal (three to six weekly), or constipation. Then, they analyzed their gut microbial makeup and measured proteins and metabolites in their blood.

    They found that participants with lower bowel movement frequency tended to be female, young, or thin and had gut microbial populations that mirrored those of people with Parkinson’s disease—who often have constipation. They also had high levels of blood metabolites associated with kidney dysfunction, neuroinflammation, cognitive decline, and vascular disease. These participants were more likely to report low fruit and vegetable intake, high snack intake, and anxiety and/or depression.

    Frequent bowel movements may reduce the overall diversity of microbes in the gut, increasing the risk of inflammation and poor health. However, infrequent bowel movements may increase levels of toxic microbial metabolites in the urine, driving chronic kidney disease and neurodegenerative disorders.

    These findings suggest that bowel movement infrequency alters gut microbial populations and increases the production of harmful metabolites. Fruits and vegetables contain bioactive compounds and dietary fiber that benefit gut health and promote regular bowel activity. This smoothie is a tasty way to get more fruits and vegetables into your diet.

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  • Cannabidiol restores the gut microbiome in cocaine users, weakening memory of the drug's reward, according to a study on mice. www.psypost.org
    Gut Microbiome Drug Cannabinoid

    Cocaine affects nearly every organ system in the body, including the gastrointestinal system, drastically altering the gut microbiome. It also increases dopamine levels in the brain, creating a memory of the dopamine reward and strengthening the association between the drug and the pleasurable feelings it produces. A recent study in mice found that cannabidiol, a non-psychoactive compound in marijuana, restores the gut microbiome in cocaine users, reversing memory-associated cocaine addiction.

    Researchers gave adult mice either cocaine + placebo or cocaine + cannabidiol. They collected fecal samples before and after the drug treatments to analyze changes in the gut microbiome.

    They found that the mice that received cocaine + placebo developed a strong preference for environments where they received the drug that lasted even after its cessation, indicating they had a memory of the reward. These mice also experienced long-lasting reductions in their gut microbial diversity. However, the mice that received cocaine + cannabidiol showed a reduced preference for the cocaine-associated environment after drug cessation and exhibited greater gut microbial diversity, with more beneficial microbes and fewer harmful ones.

    These findings suggest that cannabidiol reverses changes in the gut microbiome caused by cocaine and helps reduce the memory of cocaine’s rewarding effects. Beneficial activities like exercise and hard work also boost dopamine levels but without the massive peaks associated with cocaine use. Learn more in this clip featuring Dr. Andrew Huberman.

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  • Probiotic improves cognition and normalizes circadian rhythms in sleep-deprived mice. www.sciencedirect.com
    Brain Gut Microbiome Sleep Probiotics

    The gut microbiome is crucial for maintaining normal brain processes, and disruptions in gut health can impair cognitive function. Sleep deprivation also impairs cognitive function, but some evidence suggests that probiotics mitigate these effects. A recent study in mice found that probiotics alleviated sleep-deprivation-induced cognitive impairments.

    Researchers fed sleep-deprived mice a probiotic containing Bifidobacterium breve and subjected them to memory and behavioral tests. They also analyzed changes in the animals' gut microbial composition and the presence of crucial microbial metabolites in the gut and serum.

    They found that Bifidobacterium breve improved the sleep-deprived animals' performance in the novel object recognition test – an assessment of recognition memory. The probiotic also altered their gut microbial composition toward a more favorable profile and increased levels of isovaleric acid and gamma-aminobutyric acid (also known as GABA), metabolites involved in melatonin production and circadian rhythm regulation, respectively.

    Bifidobacterium breve is a probiotic bacterium commonly found in the human gut, with particularly large numbers found in young, breastfed infants. It is known for its beneficial effects on digestive health and immune function, and it has been studied for its potential to alleviate various conditions, including gut disorders and Alzheimer’s disease

    These findings suggest that Bifidobacterium breve mitigates sleep-deprivation-induced cognitive impairments and circadian rhythm disturbances in mice. They also highlight a potential role for gut microbial manipulation in treating insomnia and other sleep disorders. Learn more about the relationship between the gut microbiome and sleep in this clip featuring Dr. Matt Walker.

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  • A prebiotic supplement containing inulin and fructo-oligosaccharides boosts cognitive performance in older adults, indicating beneficial effects via the gut-brain axis. www.kcl.ac.uk
    Brain Gut Diet Microbiome Fiber

    The gut-brain axis, a bidirectional signaling pathway between the gastrointestinal tract and the nervous system, plays a critical role in human health, including aspects of cognition. Key elements of this pathway are the tens of trillions of microbes that comprise the intestinal microbiota. A recent study found that taking a prebiotic supplement altered the gut microbiota, improving cognitive performance in older adults.

    The randomized controlled study involved 36 older adult twin pairs. One twin within each pair consumed a prebiotic supplement containing inulin and fructo-oligosaccharides for 12 weeks, while the other twin took a placebo. Participants provided information about their daily dietary intake and underwent cognitive tests before and after the supplement intervention. Researchers analyzed the participants' gut microbial populations.

    They found that the prebiotic supplement increased the number of Bifidobacterium – a type of bacteria commonly associated with gut health – in the participants' guts. Those who took the prebiotic performed better on cognitive tests than those who took the placebo. In particular, they performed better on a paired associate learning test, a memory assessment commonly used for the early detection of Alzheimer’s disease.

    These findings suggest that prebiotics influence cognitive health via gut-brain axis interactions. Prebiotics are food components that support the maintenance of a healthy microbiota and create an environment conducive to its survival. Inulin and fructo-oligosaccharides are among the most abundant prebiotics in the human diet, present in apples, bananas, legumes, and dietary supplement forms. Their fermentation by gut microbiota produces short-chain fatty acids, including acetate, propionate, and butyrate.

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  • Omega-3s show promise in easing oral mucositis symptoms during head and neck cancer radiation therapy. bmcoralhealth.biomedcentral.com
    Cancer Microbiome Omega-3 Inflammation

    People who undergo radiation therapy for head and neck cancers often experience oral mucositis – inflammation and ulceration of the mouth and throat that makes speaking, chewing, and swallowing difficult. They also demonstrate alterations in the population of the microbes that typically inhabit the mouth – a condition called dysbiosis. However, a recent study found that people who took omega-3 fatty acids before receiving radiation therapy experienced fewer symptoms of oral mucositis than those receiving conventional therapy.

    The study involved 34 patients with head and neck cancer who were about to undergo radiation therapy. Half of the participants received conventional preventive treatment (topical antifungal and anti-inflammatory mouthwash), and the other half received a topical omega-3 gel. Researchers evaluated the patients' symptoms, pain, and quality of life at baseline, three, and six weeks after treatment and assessed changes in their oral microbiomes.

    They found that those who used the topical omega-3 gel exhibited fewer symptoms and had less pain at the six-week point than those who received the conventional treatment. They also had less microbial dysbiosis.

    These findings suggest that omega-3s reduce the symptoms associated with oral mucositis. These effects may be due to omega-3 fatty acids' potent anti-inflammatory, antioxidant, and wound-healing properties. Learn more about omega-3s in our comprehensive overview article.

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  • Vitamin B12 supports metabolic processes involved in stem cell reprogramming and tissue repair. www.irbbarcelona.org
    Gut Microbiome Genetic Engineering Micronutrients Vitamin B12

    Proteins called Yamanaka factors can reprogram differentiated (mature) cells into pluripotent stem cells. However, scientists don’t fully understand the metabolic requirements underlying this process. A new study shows that vitamin B12 supports the metabolic processes involved in cellular reprogramming.

    First, researchers investigated how gut bacteria influence cellular reprogramming in mice. They induced gene expression to initiate reprogramming, and then they treated the mice with antibiotics to disrupt their gut microbiota. They found that reprogramming efficiency in the colon and stomach decreased markedly, and the gut microbial composition changed, altering vitamin B12 metabolism.

    Next, they provided the mice with supplemental vitamin B12. They found that B12 promoted the methylation of histone H3 at a specific site known as H3K36me3, an epigenetic marker that is crucial in preventing the start of improper transcription. Then, they studied the effects of vitamin B12 deficiency in an animal model of ulcerative colitis and found that supplementing with vitamin B12 accelerated tissue repair in the colon.

    These findings suggest that vitamin B12 is pivotal in enhancing cellular reprogramming efficiency and promoting tissue repair. They also underscore B12’s importance in fundamental biological processes and point toward potential therapeutic strategies for tissue regeneration and rejuvenation. Learn more about Yamanaka factors and cellular reprogramming in this clip featuring Dr. Steve Horvath.

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  • The gut microbiome alters the brain's response to tempting foods, affecting dietary choices. www.sciencedaily.com
    Brain Obesity Microbiome Prebiotics

    The brain’s reward centers react more strongly to the sight of tempting food than to less tempting options, driving food choices. Evidence suggests the gut microbiome influences these neural activity patterns, ultimately modulating body weight and metabolic health. A recent study found that inulin, a prebiotic derived from chicory root, alters the gut microbiome, reducing the intensity of the brain’s reward system activation.

    Researchers gave 59 overweight young to middle-aged adults 30 grams of inulin or a placebo every day for two weeks. Then, the participants underwent functional MRI scans while viewing images of various foods and rating the foods' desirability. Finally, they ate the most desired food and underwent more MRIs. After a two-week break, they switched to the alternate treatment. The researchers collected blood and fecal samples from the participants before and after the two interventions.

    They found that the participants' reward-related brain activation in response to high-calorie food stimuli decreased after consuming the prebiotic inulin. A shift in the gut microbial composition accompanied these changes.

    These findings suggest that prebiotics influence dietary choices via alterations in the gut microbiome. They also highlight the complex interplay between the gut, brain, and the body’s microbial partners. Learn more about the gut microbiome in this episode featuring Dr. Eran Elinav.

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  • Gut microbes from Alzheimer's patients impair memory and neurogenesis in rats, suggesting a link between gut health and Alzheimer's disease. www.kcl.ac.uk
    Brain Alzheimer's Gut Microbiome Memory Neurogenesis

    The hippocampus, a small organ within the brain’s medial temporal lobe, is critical for memory, learning, and spatial navigation. The loss of hippocampal neurogenesis (the formation of new neurons) is an early indicator of Alzheimer’s disease. A recent study in rats shows that gut microbial transplants from people with Alzheimer’s inhibit hippocampal neurogenesis and impair memory.

    Researchers transplanted gut microbes from healthy older adults or those with Alzheimer’s disease into the guts of young adult rats. Then, using behavioral tests, they assessed the rats' cognitive function.

    They found that the rats that received transplants from people with Alzheimer’s exhibited impaired memory and altered mood – functions that rely on hippocampal neurogenesis. The extent of these impairments correlated with the donors' cognitive abilities and the presence of inflammation-promoting microbes. They also noticed differences in microbial metabolites in the rats' guts, including taurine, an amino acid that supports hippocampal neurogenesis.

    These findings suggest that symptoms of Alzheimer’s disease can be passed on to a healthy, young individual via the gut microbiota, confirming the role of the gut microbiota in causing Alzheimer’s. They also highlight the importance of developing and maintaining a healthy gut microbial population, a process that begins early in life. Learn more in this clip featuring Dr. Eran Elinav.

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  • Presence of gut microbe _Alistipes putredinis_ intensifies weight loss during physical activity, new research shows. microbiomejournal.biomedcentral.com
    Exercise Microbiome Weight Loss

    Physical activity is often a fundamental component of weight management strategies. However, some people experience weight loss with physical activity while others do not. A recent study found that differences in the gut microbiome influence the body’s metabolic response to physical activity.

    The study involved 307 healthy men and 209 healthy women enrolled in two long-term cohort studies. Researchers analyzed the participants' gut microbial makeup and assessed their physical activity levels over several years.

    They found that a specific gut microbe called Alistipes putredinis played a crucial role in how physical activity influenced body weight. Participants with higher levels of A. putredinis experienced more weight loss when they increased their physical activity. Conversely, those with lower A. putredinis levels saw less weight loss in response to physical activity. This pattern was consistent for long-term and short-term physical activity and associated with metabolic processes linked to A. putredinis, such as folate transformation and fatty acid metabolism.

    These findings suggest that having a greater abundance of A. putredinis in the gut boosts the positive effects of physical activity on weight management. Interventions aimed at manipulating the gut microbiome could enhance the effectiveness of physical activity in controlling body weight. Learn more about the gut microbiome’s roles in human health in this episode featuring Dr. Eran Elinav.

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  • Ketogenic diet may alleviate ADHD symptoms by altering gut microbiota and boosting neurotransmitter expression. journals.plos.org
    Microbiome ADHD Neurotransmitter Ketogenic Diet

    Attention deficit hyperactivity disorder (ADHD) is a common neurobehavioral condition observed in children and adults. A recent study in mice suggests that a ketogenic diet reduces symptoms of ADHD via alterations in the gut microbiota.

    Researchers conducted experiments using two groups of rats: one with ADHD-like symptoms and another without. They further divided each group into three subgroups: those fed a standard diet, those treated with methylphenidate (an ADHD drug commonly sold as Ritalin, Concerta, or others), and those fed a ketogenic diet.

    They found that both the methylphenidate and ketogenic diet interventions reduced ADHD-like behaviors, such as increased activity and hypermobility. In addition, both groups demonstrated elevated levels of various neurotransmitters, including serotonin, norepinephrine and others, in brain tissue, along with changes in the expression of key proteins related to neural signaling. Interestingly, the ketogenic diet also altered the gut microbial composition in ADHD-like rats, especially microbes involved in amino acid and sugar metabolism.

    These findings suggest that the ketogenic diet may hold promise as a novel approach for mitigating ADHD-related behavioral challenges, possibly by influencing the gut microbiota. It also underscores the robust effects the ketogenic diet has on the brain. Learn more in this clip featuring Dr. Dominic D'Agostino.

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  • Infant gut microbes including Actinobacteria and Bifidobacterium linked to improved social attention tests, suggesting a role for the microbiome in early cognitive development. neurosciencenews.com
    Brain Gut Microbiome Development

    The gut-brain axis is a complex communication system that links the gut microbial community, digestive system, and nervous system. A new study shows that the gut-brain axis plays a critical role in brain development. Infants demonstrating specific patterns of enhanced brain activity, such as rhythmic processing, exhibited unique gut microbial populations and metabolic processes.

    Researchers collected fecal samples from 56 infants between the ages of four and six months and analyzed their microbial composition through metagenomic sequencing. They evaluated the infants' brain activities while listening to a rhythmic beat via electroencephalogram (EEG). Then, using behavioral tests, they assessed aspects of the infants' cognitive abilities, including neural rhythm tracking, language discrimination, and joint attention.

    They found that infants who performed well in the joint attention test exhibited specific gut microbial patterns that included higher numbers of Actinobacteria, Bifidobacterium, and Eggerthella, and lower numbers of Firmicutes, Hungatella, and Streptococcus. The EEGs revealed unique neural activity patterns associated with enhanced rhythmic processing, which varied according to the presence of specific microbes. In addition, these neural activity patterns were associated with upregulated metabolic processes involving microbes linked with neurodevelopment.

    Neural rhythm tracking facilitates information organization across time, influencing perception, social communication, language, and cognition. Language discrimination differentiates between language and non-language. Joint attention is a social skill that influences infants' capacity to learn from others, affecting early language acquisition and overall cognition.

    This study was small; however, its findings suggest a potential connection between the gut microbiome and early cognitive development. It also highlights the intricacies of the gut-brain axis, with potential implications for understanding early brain development and cognitive function. Learn more about the role of the gut microbiota in this episode featuring Drs. Erica and Justin Sonnenburg.

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  • Kombucha reduces blood glucose levels by nearly 30 percent. www.frontiersin.org
    Nutrition Gut Diet Microbiome Diabetes

    Kombucha is a fermented beverage made from tea, sugar, bacteria, and yeast. Some evidence suggests that kombucha exerts antimicrobial, antioxidant, detoxifying, and liver-protective effects. A new study has found that kombucha lowers blood glucose levels by nearly 30 percent in people with type 2 diabetes.

    Researchers conducted a small trial involving 12 adults with type 2 diabetes. The participants drank approximately 8 ounces of either kombucha or a placebo beverage daily for four weeks. Eight weeks later, they switched to the other option. During each intervention, they measured their fasting blood glucose levels at the start and after one and four weeks. They completed questionnaires about their overall health, insulin needs, gut health, skin condition, and mental state. The researchers analyzed the kombucha’s microbiota and quantified its fermentation products.

    When the participants drank the kombucha, they experienced a notable drop in average fasting blood glucose levels by the end of the intervention compared to the start (164 versus 116 mg/dL – nearly 30 percent lower). However, the placebo group did not experience the same reduction (162 versus 141 mg/dL – less than 13 percent lower). The microbiota analysis revealed lactic acid bacteria, acetic acid bacteria, and yeast as the dominant components. The primary fermentation products were lactic acid, acetic acid, and ethanol.

    This was a very small study, but the findings suggest that kombucha might have blood glucose-lowering potential for people with diabetes. Learn how consuming fermented foods, such as kombucha, kefir, and others, increases gut microbial diversity and decreases inflammation in this clip from a live Q&A with Dr. Rhonda Patrick.

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  • The unique balance of gut viruses, termed the virome, may hold the secret to centenarians' longevity, new research proposes. healthsciences.ku.dk
    Aging Microbiome Immune System Virus

    The gut virome – the collection of viruses inhabiting the gut – plays a crucial role in shaping the immune system and defending against infections throughout the lifespan. A new study shows that centenarians' viromes differ from those of younger people, potentially contributing to their longevity.

    Researchers examined the gut viromes of centenarians and compared them with those of younger people. Then they analyzed the viruses' auxiliary metabolic gene activity. Auxiliary metabolic genes are found in bacteriophages – viruses that infect bacteria. They help viruses manipulate their host cells' metabolism to facilitate viral replication.

    They found that the centenarians exhibited more diverse viromes than younger people. In addition, the centenarians' viromes demonstrated increased lytic activity, indicating that their viromes were more active in infecting and destroying bacterial cells. Finally, they found that the centenarians' gut viruses possessed an abundance of auxiliary metabolic genes involved in sulfate metabolism, the byproducts of which promote gut integrity and pathogen resistance.

    These findings suggest that centenarians' viromes differ markedly from those of younger people in terms of makeup and activity, potentially contributing to centenarians' healthspan and longevity. Learn more about the role gut microbial populations play in human health in this episode featuring Dr. Eran Elinav.

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  • Swabbing C-section newborns with their mothers' vaginal fluid promotes healthier neurodevelopment at 3 and 6 months, bridging the gap to vaginally del www.newscientist.com
    Microbiome Immune System Pregnancy Development

    Infants born by cesarean section have different microbial communities in and on their bodies than those born vaginally, potentially increasing their risk of developing certain diseases, such as asthma and obesity. But a new study shows that vaginal microbiota transfer – exposing newborns to fluids from their mother’s vagina – may rectify these differences.

    The study involved 68 infants born by cesarean section. Researchers swabbed the infants' skin with sterile gauze soaked in either the mother’s vaginal fluids or saline immediately after birth. They assessed the infants' neurodevelopment at three and six months of age and analyzed the microbial makeup of the infants' guts.

    They found that infants who received vaginal microbiota transfer scored higher on neurodevelopment assessments than those who received saline. They also had healthier, more mature gut microbiomes – comparable to infants born vaginally.

    These findings suggest that exposing infants born via cesarean section to their mother’s vaginal fluids promotes appropriate neurodevelopment and corrects alterations in gut microbial populations. Learn more about the importance of establishing a healthy microbiome early in life in this clip featuring Dr. Eran Elinav.

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  • Melatonin, commonly used to improve sleep, may aggravate bowel inflammation by increasing TNF-alpha in acute colitis medicalxpress.com
    Gut Microbiome Inflammation Melatonin

    From the abstract:

    In acute colitis, the hormone (melatonin) (MLT) led to increased clinical, systemic and intestinal inflammatory parameters. During remission, continued MLT administration delayed recovery, increased TNF, memory effector lymphocytes and diminished spleen regulatory cells. MLT treatment reduced Bacteroidetes and augmented Actinobacteria and Verrucomicrobia phyla in mice feces. Microbiota depletion resulted in a remarkable reversion of the colitis phenotype after MLT administration, including a counter-regulatory immune response, reduction in TNF and colon macrophages. There was a decrease in Actinobacteria, Firmicutes and, most strikingly, Verrucomicrobia phylum in recovering mice. Finally, these results pointed to a gut-microbiota-dependent effect of MLT in the potentiation of intestinal inflammation.

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  • Blocking activity of aryl hydrocarbon receptor in T Cells shuts off multiple sclerosis autoimmunity newsroom.uvahealth.com
    Brain Gut Microbiome Multiple Sclerosis Autoimmunity

    Blocking a key regulator of autoimmunity reduces the inflammation associated with multiple sclerosis.

    A protein found on the surface of some immune cells regulates autoimmunity in multiple sclerosis, a new study has found. Blocking the protein’s activity reduced the inflammation associated with the disease.

    Researchers studied the role that the aryl hydrocarbon receptor – a protein found on specific immune cells called T cells – plays in autoimmunity in a mouse model of multiple sclerosis. They bred mice that lacked the aryl hydrocarbon receptor and examined the effects its absence had on T cell activity.

    They found that the absence of the aryl hydrocarbon receptor altered the types and numbers of microbial metabolites produced in the animals' guts. Specifically, the microbes produced more bile acids and short-chain fatty acids – both of which exhibit robust anti-inflammatory properties.

    Multiple sclerosis (MS) is a progressive autoimmune disorder that targets the central nervous system. A dominant feature of MS is inflammation of the nerves. T cells play an instrumental role in the inflammation and pathophysiology of MS.

    These findings suggest that blocking the key regulator of inflammation in MS prevents the inflammation associated with the disease. Some evidence suggests that the fasting-mimicking diet reduces the number of autoimmune cells in people with multiple sclerosis. Learn more in this episode featuring Dr. Valter Longo.

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  • Gut microbes may drive the motivation to exercise. medicalxpress.com
    Exercise Brain Microbiome Microbes Dopamine

    Microbes in your gut may trigger your motivation to exercise, a new study in mice has found. Compounds produced by the microbes signal the release of dopamine – a neurotransmitter produced in the brain that promotes the “runner’s high” and the desire to exercise.

    Researchers analyzed the gut microbial species and the byproducts of their metabolism from nearly 200 mice with diverse genetic backgrounds. They also tracked the animals' daily exercise activity and measured their endurance.

    They found that mice that had certain species of gut microbes – Eubacterium rectale and Coprococcus eutactus – exercised more and had greater endurance than mice lacking these microbes. These two species produce compounds called fatty acid amides, which interact with gut neurons and ultimately activate dopamine-producing neurons in the brain, turning on the brain’s reward circuits and triggering the desire to exercise00394-0.pdf).

    This study in mice reveals a novel way in which the gut microbiome influences human health and behavior. It may also provide evidence to support the use of therapeutic microbial transfer to promote exercise behavior and improve aspects of mood.

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  • Gut microbes may play a role in controlling the motivation to exercise by modulating runner's high www.sciencedaily.com
    Exercise Microbiome Microbes Dopamine

    Microbes in your gut may trigger your motivation to exercise, a new study in mice has found. Compounds produced by the microbes signal the release of dopamine – a neurotransmitter produced in the brain that promotes the “runner’s high” and the desire to exercise.

    Researchers analyzed the gut microbial species and the byproducts of their metabolism from nearly 200 mice with diverse genetic backgrounds. They also tracked the animals' daily exercise activity and measured their endurance.

    They found that mice that had certain species of gut microbes – Eubacterium rectale and Coprococcus eutactus – exercised more and had greater endurance than mice lacking these microbes. These two species produce compounds called fatty acid amides, which interact with gut neurons and ultimately activate dopamine-producing neurons in the brain, turning on the brain’s reward circuits and triggering the desire to exercise.

    This study in mice reveals a novel way in which the gut microbiome influences human health and behavior. It may also provide evidence to support the use of therapeutic microbial transfer to promote exercise behavior and improve aspects of mood.

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  • Long-term estrogen supplementation may affect gut microbiome composition and thus estrogen metabolism. (2018) www.sciencedaily.com
    Microbiome Hormones Estrogen

    From the article:

    “Our findings indicate that clinicians might be able to manipulate the gut biome through probiotics to change the half-life and properties of estrogens so that long-term users obtain the therapeutic benefits of estrogen-replacement therapy without increasing their risks of reproductive cancers,” said Madak-Erdogan, also the director of the Women’s Health, Hormones and Nutrition Lab at the U. of I.

    […]

    “We observed that both levels of fecal _GUS [B-glucuronidase] activity and glucuronic acid – a byproduct of estrogen metabolism – decreased after the mice were treated with conjugated estrogens and bazedoxifene_ [selective estrogen receptor modulator (SERM)],” Madak-Erdogan said. “This supported our hypothesis that estrogen supplementation affects the gut microbiome composition and estrogen metabolism.

    “While the overall diversity of microbiota was not changed significantly, we found that the activities of several bacteria taxa were altered by the estrogen therapy,” Madak-Erdogan said. “The levels of several bacteria associated with GUS [B-glucuronidase] activity in the gut decreased, including levels of akkermansia,” a family of bacteria believed to have anti-inflammatory properties in humans.

    […]

    However, mice with higher levels of akkermansia in their fecal biome gained more weight, had larger livers and more estrogen metabolites in their systems, the researchers found.

    In examining the abundance of common bacterial families in the fecal microbiota, the researchers found higher levels of several microbes, including lactobacillus and streptococcus. Lactobacillus was shown to be associated with GUS activity in previous studies by other researchers while GUS was identified in a subspecies of streptococcus.

    View full publication

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  • The gut microbiome influences brain development and social skills – could it be an effect of reduced synaptic pruning? www.quantamagazine.org
    Nutrition Brain Gut Diet Microbiome Autism Development

    The gut microbiome influences the development of social skills later in life, a recent study in fish has found. Fish that have delayed microbiome development show distinct differences in their brain structure and behavior compared to those with appropriately timed development.

    Researchers studied zebrafish, which are naturally social, to see how the microbiome affected the animals' behavior. Using a special type of zebrafish that lacked a microbiome, they inoculated one group of fish with bacteria immediately after birth to promote microbiome development. They delayed the inoculation of another group of fish by one week.

    They found that the fish that had delayed microbiome development exhibited more neural circuits in their brains and fewer microglia – a type of immune cell that “prunes” the brain and is necessary for normal development. These fish were also less social than the fish that had appropriately timed microbiome development.

    This study suggests that the microbiome influences the social behavior of zebrafish by reducing microglial pruning. Although the study was conducted using fish, other research suggests that these findings could translate to mammals, including humans. Learn more about the role of the gut microbiome in this episode featuring Dr. Eran Elinav.

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  • Our gut microbiomes aren’t getting enough fibre, but supplements can help apple.news
    Gut Microbiome Fiber Supplements

    Prebiotic supplements can compensate for low fiber intake.

    Dietary fiber refers to the indigestible components of plant-based foods. A growing body of evidence indicates that eating a fiber-rich diet decreases the risks of many chronic diseases, such as coronary heart disease, stroke, hypertension, diabetes, and some types of cancer, including breast cancer and colon cancer. Most people living in the United States only get about half of the recommended amounts of fiber daily. Findings from a recent study suggest that prebiotic supplements can compensate for dietary shortcomings in fiber intake by promoting short-chain fatty acid production.

    Prebiotics are food components that support the maintenance of a healthy microbiota and create an environment that is conducive to its survival. Fructo-oligosaccharides, galacto-oligosaccharides, and trans-galacto-oligosaccharides are the most common prebiotics. Their fermentation by gut microbiota produces short-chain fatty acids, including acetate, propionate, and butyrate. Many commonly consumed fruits and vegetables, such as apples, bananas, and legumes, contain prebiotics, but they are also available in dietary supplement form.

    The study involved 28 healthy adults between the ages of 18 and 70 years. Each participant took one of three prebiotic supplements (inulin, wheat dextrin, or galactooligosaccharides) twice daily for one week, followed by one week off. They repeated this process with all three of the supplement products. Participants provided stool samples, completed diet surveys, and answered online surveys about their experiences with the supplements. The investigators measured short-chain fatty acid concentrations and microbial makeup in the stool samples.

    They found that changes in short-chain fatty acid concentrations were person-specific and not related to which prebiotic supplement they took. Consequently, each participant’s response to the prebiotics was inversely related to their basal short-chain fatty acid concentration, which, in turn, was associated with their habitual fiber intake. Participants whose diets were low in dietary fiber experienced marked increases in butyrate production in their guts, likely due to increases in butyrate-producing microbes. However, participants whose diets were in high in dietary fiber experienced little change in the makeup of their gut microbes.

    These findings suggest that people whose diets are low in dietary fiber would benefit from supplemental prebiotics to promote short-chain fatty acid production and promote gut and overall health. Learn more about prebiotics in this episode featuring Dr. Eran Elinav.

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  • Time-restricted feeding restores healthy circadian oscillations in the ileal microbiota. medicalxpress.com
    Microbiome Circadian Rhythm Time-Restricted Eating

    Compositional oscillations of the gut microbiome are essential for normal peripheral circadian rhythms, both of which are disrupted in diet-induced obesity (DIO). Although time-restricted feeding (TRF) maintains circadian synchrony and protects against DIO, its impact on the dynamics of the cecal gut microbiome is modest. Thus, other regions of the gut, particularly the ileum, the nexus for incretin and bile acid signaling, may play an important role in entraining peripheral circadian rhythms. We demonstrate the effect of diet and feeding rhythms on the ileal microbiome composition and transcriptome in mice. The dynamic rhythms of ileal microbiome composition and transcriptome are dampened in DIO. TRF partially restores diurnal rhythms of the ileal microbiome and transcriptome, increases GLP-1 release, and alters the ileal bile acid pool and farnesoid X receptor (FXR) signaling, which could explain how TRF exerts its metabolic benefits. Finally, we provide a web resource for exploration of ileal microbiome and transcriptome circadian data.

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  • The microbiome of people with Alzheimer's disease may mediate disease risk. content.iospress.com
    Brain Alzheimer's Microbiome

    Alzheimer’s disease, the most common cause of dementia, has been the subject of a large body of research in recent decades. However, the number of effective therapies for the disease is small, demonstrating the need for additional research into the mechanisms of dementia. Findings from a group of scientists researching the gut microbiota suggest the microbiota-gut-brain axis may contribute to Alzheimer’s pathology.

    The microbiota-gut-brain axis is a recently developed way to understand the relationship between the behavior of microbes in the gut and behaviors generated by the brain. This bidirectional highway of information delivers commands from the brain to the gut using nervous and endocrine signals and sends information from bacteria in the gut to the brain using nervous, circulatory, and immune pathways. Previous research has identified alterations in the composition and function of the gut microbiota in people with neurodegenerative diseases such as Parkinson’s disease and amyotrophic lateral sclerosis; however, the relationship between the microbiota and brain in people with Alzheimer’s disease requires additional research.

    The authors recruited 43 participants who had Alzheimer’s disease and 43 healthy participants who were matched with age and sex. Participants completed questionnaires about their mental health and cognitive function and provided a stool sample, which the researchers used to sequence the bacterial DNA in each participants' gut microbiome. Finally, the researchers selected twelve participants to receive a positron emission tomography (PET) scan to measure amyloid-beta deposition in the brain, which is the clinically standard way to diagnose Alzheimer’s disease.

    The microbiome of participants with Alzheimer’s disease differed from those without Alzheimer’s disease at the phylum, order, and family levels (i.e., scientific categories used to organize microbes into groups using their genes), with higher levels of phyla Bacteroidetes and lower levels of the phyla Actinobacteria and Verrucomicrobia and family Ruminococcaceae. Altered levels of these bacteria may be related to diet, as previous research has shown that some members of the Ruminococcaceae produce harmful compounds from bile acids released by the liver in response to dietary fat. Also, Akkermansia muciniphila, a member of the Verrucomicrobia has been shown to produce beneficial products from dietary fibers, but may increase inflammation and attack the gut barrier in diseases such as ulcerative colitis.

    In this cross-sectional study, the authors found important differences between the microbiomes of participants with and without Alzheimer’s disease. The authors did not measure microbial metabolites in this study; however, the authors suggest these compounds are a key mechanisms of these associations.

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  • Gut microbiota predicts body fat change following a low-energy diet. genomemedicine.biomedcentral.com
    Diet Obesity Microbiome

    Very low-calorie diets elicit extensive changes to the gut microbiota, influencing weight loss.

    Many popular diet programs emphasize calorie reduction as a means to lose weight. However, this approach to weight loss minimizes evidence suggesting that the gut microbiota plays important roles in body weight and likely influences the host’s metabolic response to diet. Findings from a recent study suggest that very low-calorie diets elicit extensive changes to the gut microbiota, influencing how much weight a person loses when dieting.

    Low-calorie diets (1,200 to 1,500 calories per day) and very low-calorie diets (less than 800 calories per day) have gained popularity in recent decades. These diets often rely on the use of meal replacements, typically in the form of ready-made meals, shakes, or bars. When combined with behavior modification, evidence suggests that low-calorie and very low-calorie diets are useful strategies for losing weight.

    The investigators drew on data from the PREVIEW study, a three-year lifestyle intervention study aimed at type-2 diabetes prevention. The current study involved more than 2,200 adults (aged 20 to 70 years) with overweight or obesity and pre-diabetes. Participants consumed a meal replacement that provided approximately 810 calories and 13 grams of fiber daily for eight weeks. They were also allowed to consume up to 400 grams (about 200 calories) of non-starchy vegetables daily. Before and after the intervention, participants provided fecal samples for microbial sequencing.

    The investigators observed that the overall makeup of the participants' gut microbial populations underwent considerable changes over the eight-week intervention. Not only did microbial numbers (termed “richness”) increase, but the diversity of microbes increased, as well. In addition, the numbers of bacteria that may be beneficial for metabolic health, such as Akkermansia and _ Christensenellaceae_, increased, but butyrate production decreased, an indication of fewer butyrate-producing microbes. Butyrate plays important roles in maintaining gut health. These changes were correlated with changes in body fat and weight.

    These findings suggest that very low-calorie diets induce marked changes in the overall composition of microbes in the gut, influencing changes in body fat and weight. Other issues complicate weight loss, however. For example, excess body weight has profound, deleterious effects on the gut microbiome, driving dysbiosis and impairing critical aspects of nutrient metabolism. Of particular concern is the inability to metabolize flavonoids, some of which participate in fat metabolism. This dysbiosis persists, even after weight loss, likely promoting recurrent (or “yo-yo”) obesity. Learn more about this phenomenon in this clip featuring Dr. Eran Elinav.

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  • Curcumin may act as an intervention in chronic urinary tract infection through dampening of toll-like receptors and reducing bacterial colony count pubmed.ncbi.nlm.nih.gov
    Microbiome Immune System Curcumin Microbes Toll-Like Receptors

    Curcumin reduces urinary tract infection symptoms via interaction with toll-like receptors.

    Urinary tract infections are common outpatient infections. They occur more frequently among women, and 50 to 60 percent of all women report having had at least one UTI in their lifetime. Findings from a 2017 study suggest that curcumin reduces the symptoms associated with urinary tract infections via interaction with toll-like receptors.

    Toll-like receptors comprise a family of pattern recognition receptors expressed on the surfaces of immune and other cells. They are the principal inducers of innate immunity and are responsible for the activation of transcription factors that increase the expression of proinflammatory cytokines. Chronic infections of the urinary tract, which either don’t respond to treatment or keep recurring, can occur in some people.

    Curcumin is a bioactive compound found in the roots of Curcuma longa, a type of tropical plant. It is responsible for the vibrant yellow color of the spice turmeric. Evidence suggests that curcumin exerts robust antioxidant, anti-inflammatory, and anticancer effects. Curcumin also exhibits antibacterial activity, but the compound is strain-specific.

    The study involved rats that had chronic urinary tract infections. Half of the rats received a curcumin injection, while the other half did not. The investigators measured the animals' white blood cell counts, bacterial counts (in the bladder and urine), markers of inflammation, and expression of toll-like receptor (TLR)2 and TLR4.

    They found that white blood cell counts, bacterial counts, markers of inflammation, and expression of TLR2 and TLR4 of the rats that received the curcumin injection were considerably lower than those of the rats that didn’t receive curcumin. These findings suggest that curcumin improves the symptoms of chronic urinary tract infections and reduces inflammatory responses via dampening the expression of TLR2 and TLR4.

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  • Fecal microbial transplants from young to old mice reverse the hallmarks of aging. www.sciencedaily.com
    Aging Microbiome

    Scientists have identified several hallmarks of aging – observable biological patterns of dysfunction that occur as an organism ages. These hallmarks both drive and are the result of inflammaging, the chronic, low-grade inflammation that occurs with aging. Findings from a recent study suggest that fecal microbial transplants reverse the hallmarks of aging.

    As a person ages, the overall makeup of the population of microbes that inhabit their gut undergoes extensive changes. These changes are associated with increased inflammation, altered metabolic health and immune function, and an increased risk of chronic disease. Fecal microbial transplant is a therapeutic strategy that involves transfer of microbial-rich feces from a donor to a recipient. The goal of fecal microbial transplant is to restore the microbial balance in the gut of the recipient as a means to improve health.

    The investigators performed fecal microbial transplants first between young mice and aged mice and then vice versa. They sequenced the bacterial populations in the fecal samples before and after transplantation. Then they assessed the effects of the transplants on inflammatory hallmarks of aging (specifically, protein levels, immune function, and behavior).

    They found that fecal microbial transplantation from aged to young mice elevated systemic and tissue markers of inflammaging, accelerated age-related inflammation in the central nervous system and retina, drove the loss of key functional proteins in the retina, and promoted intestinal barrier permeability (sometimes referred to as “leaky gut”). However, transplantation from young to old mice reversed these effects.

    These findings suggest that age-related changes in the gut microbiota promote inflammation, driving increased gut permeability, retina dysfunction, and impaired brain health, and contributing to the hallmarks of aging. Learn more about the hallmarks of aging in our comprehensive overview article.

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  • A Low Glycemic Index Mediterranean Diet Combined with Aerobic Physical Activity Rearranges the Gut Microbiota Signature in NAFLD Patients www.mdpi.com
    Exercise Diet Microbiome

    A low-glycemic index Mediterranean diet and aerobic exercise corrects gut microbial imbalance in people with fatty liver disease.

    Non-alcoholic fatty liver disease, or NAFLD, is a syndrome that encompasses multiple states of liver dysfunction, including steatosis (fatty liver), nonalcoholic steatohepatitis, and cirrhosis. It is the most common liver chronic liver condition among people living in the United States, affecting roughly 90 percent of people with obesity, or about 25 percent of the overall population. A dominant feature of NAFLD is dysbiosis, an imbalance in the types and numbers of microbes in the gut. Findings from a recent study suggest that eating a low-glycemic index Mediterranean diet and engaging in aerobic exercise restores gut microbial balance in people with NAFLD.

    Glycemic index refers to a value (between 0 and 100) assigned to a defined amount of a carbohydrate-containing food based on how much the food increases a person’s blood glucose level within two hours of eating, compared to eating an equivalent amount of pure glucose, which has a value of 100. Whereas eating high glycemic index foods induces a sharp increase in blood glucose levels that declines rapidly, eating low glycemic index foods generally results in a lower blood glucose concentration that declines gradually.

    The Mediterranean dietary pattern is rich in foods that have a low glycemic index, including fruits, vegetables, olive oil, legumes, fish, and poultry. Previous research demonstrated that a Mediterranean diet in conjunction with aerobic exercise improves measures of NAFLD but did not identify the mechanism that drove these improvements.

    The current study involved 109 adults (average age, 53 years) who had been diagnosed with NAFLD. The investigators randomly assigned the participants to receive one of six interventions: low glycemic index Mediterranean diet; aerobic exercise program (with or without the low glycemic index Mediterranean diet); combined aerobic exercise and resistance training program (with or without the low glycemic index Mediterranean diet); or no intervention. The investigators collected stool samples from the participants and sequenced the microbial populations in the samples.

    They found that compared with other dietary/exercise interventions, a low-glycemic index Mediterranean diet in conjunction with aerobic exercise exerted robust effects on the participants' gut microbial population. These effects corrected the participants' dysbiosis and promoted increases in populations of microbes that benefit gut health, including Akkermansia, Firmicutes, and Ruminococcaceae.

    These findings suggest that dietary measures in conjunction with exercise have favorable effects on the gut microbiota of people with NAFLD, providing insights into the mechanisms that drive improvements in disease status. Evidence from cell culture studies suggests that berberine, a bioactive dietary compound, provides protection against NAFLD. Read our overview article to learn more about berberine.

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  • Microbiota play important role in preventing blood-brain barrier permeability: germ-free mice have greater leakiness, resolved with fecal transplant www.sciencedaily.com
    Brain Microbiome Blood-Brain Barrier

    From the article:

    The investigators reached this conclusion by comparing the integrity and development of the blood-brain barrier between two groups of mice: the first group was raised in an environment where they were exposed to normal bacteria, and the second (called germ-free mice) was kept in a sterile environment without any bacteria.

    “We showed that the presence of the maternal gut microbiota during late pregnancy blocked the passage of labeled antibodies from the circulation into the brain parenchyma of the growing fetus,” says first author Dr. Viorica Braniste at the Department of Microbiology, Tumor and Cell Biology at Karolinska Institutet. “In contrast, in age-matched fetuses from germ-free mothers, these labeled antibodies easily crossed the blood-brain barrier and was detected within the brain parenchyma.”

    However, it can be resolved with fecal transplant:

    Interestingly, this ‘leakiness’ could be abrogated if the mice were exposed to fecal transplantation of normal gut microbes.

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  • Reduced expression of genes involved in integrity of blood-brain barrier, intestinal barrier in autism: 75% have reduced barrier-forming components www.sciencedaily.com
    Brain Microbiome Autism Intestinal Permeability Endotoxemia Blood-Brain Barrier

    From the article:

    The group analyzed postmortem cerebral cortex and cerebellum tissues from 33 individuals – 8 with ASD, 10 with schizophrenia and 15 healthy controls. Altered expression of genes associated with blood-brain-barrier integrity and function and with inflammation was detected in ASD tissue samples, supporting the hypothesis that an impaired blood-brain barrier associated with neuroinflammation contributes to ASD.

    In keeping with the hypothesis that the interplay within the gut-brain axis is a crucial component in the development of neurodevelopmental disorders, the group also analyzed intestinal epithelial tissue from 12 individuals with ASD and 9 without such disorders. That analysis revealed that 75 percent of the individuals affected by ASD had reduced expression of barrier-forming cellular components, compared with controls, and 66 percent showed a higher expression of molecules that increase intestinal permeability.

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  • Mid-life long duration antibiotic use of >= two months linked to poorer scores in cognition, learning, working memory, and attention in later life www.sciencealert.com
    Brain Aging Microbiome Performance Memory Antibiotics Dementia

    Antibiotic use in midlife increases a person’s risk for neuropsychiatric diseases.

    Antibiotics are prescribed for a wide range of infectious diseases. In 2015, healthcare providers in the United States wrote nearly 270 million antibiotic prescriptions – more than 800 antibiotic prescriptions for every 1,000 people. Health experts estimate that 30 percent of these prescriptions were likely unnecessary. Findings from a new study suggest that antibiotic use in midlife increases a person’s risk for neuropsychiatric diseases.

    The study included approximately 15,000 midlife participants (average age, 55 years) enrolled in the Nurses’ Health Study II, an ongoing prospective cohort study of female nurses. The participants completed questionnaires regarding their general health, diet, lifestyle, and medication use during the previous four years, including antibiotic use and the reason for which the antibiotic was prescribed. The investigators categorized the participants' cumulative antibiotic use as none, one to 14 days, 15 days to two months, and two months or more. Participants also completed a battery of neuropsychological tests.

    The investigators found that participants who took antibiotics for at least two months over the previous four years were more likely to perform worse on neuropsychological tests than participants who did not take antibiotics. The influence of antibiotic use on neuropsychological test scores was roughly equivalent to three to four years of aging. These findings held true even after considering other factors that could influence cognitive function, including age and coexisting illnesses.

    These findings suggest that longer exposure to antibiotics in midlife negatively influences cognitive health, underscoring the importance of moderating antibiotic use in older adults. They also support findings from animal studies that suggest antibiotic use early in life alters neuropeptide signaling pathways that influence behavioral development. Learn more about the effects of antibiotic use in early life in this clip featuring Dr. Eran Elinav.

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  • Resistant starch may reduce colorectal cancer risk associated with red meat consumption www.sciencedaily.com
    Cancer Diet Microbiome Fiber

    Resistant starch reduces colorectal cancer risks associated with a high-red meat diet.

    Colorectal cancer is the third most common cancer worldwide. Robust evidence suggests that red meat consumption markedly increases a person’s risk of developing colorectal cancer.. Findings from a 2014 study suggest that resistant starch consumption alters microRNA expression, potentially moderating the cancer risks associated with red meat consumption.

    Resistant starch is a type of carbohydrate that resists digestion in the small intestine. Instead, resistant starch undergoes microbial fermentation in the colon, providing nutrients for the microbes and producing butyrate, a short-chain fatty acid that supports the health of colonocytes – the cells that line the colon and rectum (the end portion of the colon). Foods that contain resistant starch include breads, pasta, legumes, nuts, seeds, bananas, and starchy vegetables, such as potatoes. Cooking and preparation techniques alter resistant starch content in foods, however. For example, a study found that a 3-ounce portion of baked potatoes typically provides 3.6 grams of resistant starch, but a similar portion of boiled potatoes provides just 2.4 grams.

    MicroRNAs are single-stranded RNA molecules that play roles in the regulation of gene expression. They calibrate as much as 30 percent of mammalian protein-encoding genes. MicroRNA expression is typically dysregulated in the setting of cancer. However, evidence from an in vitro study suggests that butyrate modulates microRNA expression in colorectal cancer cells.

    The study involved 23 healthy adults between the ages of 50 and 75 years old. Each participant followed two four-week-long dietary interventions (separated by a washout diet): a high-red meat diet (providing 300 grams of red meat daily – about three-fourths of a pound) and a high-red meat diet that also provided 40 grams of butyrylated resistant starch, a chemically modified form of resistant starch that is an effective vehicle for delivering butyrate to the colon. The investigators collected rectal tissue samples via biopsy at the completion of each intervention diet.

    After completing the high-red meat diet, the participants' rectal tissues exhibited a 30 percent increase in a cluster of microRNAs called microRNA 17-92, which participates in the cell cycle, proliferation, apoptosis (cell death), and other processes involved in cancer. But when the participants added resistant starch to their high-red meat diet, their microRNA 17-92 levels returned to baseline levels.

    These findings suggest that butyrylated resistant starch moderates the cancer-promoting effects of a diet high in red meat. Some of this benefit may arise from the delivery of butyrate. Learn more about butyrate in our overview article.

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  • Butyrate may protect against graft-versus-host disease after bone marrow transplants, suggests animal research www.sciencedaily.com
    Gut Diet Microbiome Immune System Butyrate

    From the article:

    In a new study, published in Nature Immunology, researchers searched for alterations in the gut microbiome to see whether their metabolites could impact outcomes after BMT.

    They found that a metabolite called butyrate was significantly reduced in the intestinal tract of experimental mice that received bone marrow transplant. When the researchers increased butyrate in these mouse models, they saw a decrease in the incidence and severity of graft vs. host disease.

    “Our findings suggest we can prevent graft vs. host disease by bolstering the amount of the microbiome-derived metabolite butyrate,” says study lead author Pavan Reddy, M.D., the Moshe Talpaz Professor of Translational Pathology and interim division chief of hematology/oncology at the University of Michigan.

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  • Salt may increase blood pressure partly through reducing the production of ketone beta-hydroxybutyrate www.sciencedaily.com
    Exercise Gut Diet Microbiome Ketosis Heart Disease Blood Pressure

    From the article:

    “Our team found that high salt consumption lowered levels of circulating beta hydroxybutyrate. When we put beta hydroxybutyrate back in the system, normal blood pressure is restored,” said Dr. Bina Joe, Distinguished University Professor and chair of UT’s Department of Physiology and Pharmacology and director of the Center for Hypertension and Precision Medicine. “We have an opportunity to control salt-sensitive hypertension without exercising.”

    The effects may be microbiome mediated. Read the following excerpt from discussion in a Cell spotlight:

    Changes in the microbiota, specifically a decrease in Lactobacillus spp., in rats fed a high-salt diet have also been implicated in drivingthe progression of hypertension. The authors found that Lactobacillus spp. and Proteobacteria were reduced and Prevotella spp. were increased by a high-salt diet. The changes in the microbiota were associated with a decrease in gluconeogenesis and ketone metabolism, which was not restored by supplementation with 1,3-butanediol. Interestingly, after 1,3butanediol treatment, Proteobacteria and Prevotella shifted back toward the low-salt relative abundance and also correlated with an increase in protective Akkermansia levels.

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  • A type of virus present in the gut microbiota is associated with better cognitive ability in humans, mice and flies www.sciencedaily.com
    Microbiome Virus

    Bacteriophages may influence the capacity to learn and remember information.

    The gut microbiome plays many roles in human physiology, including aspects of brain and neurological health. Because the overall microbial makeup of the microbiome stabilizes around the age of three years, reconfiguring an unfavorable balance with dietary measures or via fecal microbial transplantation has shown limited success. In recent years, scientists have turned to bacteriophages as a possible means of restoring imbalances. Interestingly, bacteriophages may serve other purposes, as demonstrated in findings from a recent study showing that bacteriophages may influence an animal’s ability to learn and remember information.

    Bacteriophages (often referred to simply as “phages”) are viruses that infect bacteria. They are abundant in the human gut and exert disparate effects on human health, as seen in their potential roles in resolving bacterial infections and in the pathogenesis of Parkinson’s disease. Bacteriophages are species-specific and typically only infect a single bacterial species or even specific strains within a species. The dominant bacteriophages in the human gut are those of the Caudovirales and Microviridae families.

    The study involved more than 1,000 adult participants enrolled in the Ageing Imagenoma Project, an ongoing study of aging patterns among healthy adults (50 years and older) living in Girona, Italy. Participants completed food questionnaires and underwent a battery of cognitive tests, with special emphasis on executive function, one of the key domains of cognitive function.

    Investigators collected fecal samples from the participants and measured the viral species present. Interestingly, participants who consumed higher quantities of dairy products tended to have more Caudovirales bacteriophages in their guts. The researchers transplanted fecal samples from the participants into the guts of mice and performed cognitive tests on the mice. Mice that received fecal transplants from participants with more Caudovirales viruses performed better on the cognitive tests than mice that received transplants with fewer Caudovirales.

    Next, they fed fruit flies either ordinary whey powder (a dairy product that contains bacteriophages) or sterilized, virus-free whey powder. Then they duplicated the experiment using isolated bacteriophages. In both scenarios, production of genes in the flies' brains that are associated with memory increased.

    These findings suggest that bacteriophages, especially those of the Caudovirales family, influence aspects of cognitive function and underscore the potential for capitalizing on the beneficial roles of viral species in the human gut. Learn more about bacteriophages in this interview featuring gut microbiome expert Dr. Eran Elinav.

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  • Rebalancing gut microbiome with butyrate lengthens survival in mouse model of ALS by repairing intestinal permeability www.sciencedaily.com
    Brain Aging Microbiome Neurodegeneration Butyrate Intestinal Permeability

    From the article:

    In a mouse model of ALS, the compound butyrate helped correct a gut microbiome imbalance and reduced gut leakiness – both symptoms of ALS. The treated mice lived also longer compared to mice that weren’t given butyrate.

    […]

    When the researchers fed the ALS-prone mice butyrate in their water, starting when the mice were 35 to 42 days old, the mice showed a restored gut microbiome profile and improved gut integrity. Butyrate-treated mice also showed improved neuromuscular function and delayed onset of ALS symptoms. Treated mice showed symptoms at 150 days old compared to control mice at about 110 days. Treated mice also lived an average 38 days longer than mice not given butyrate.

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  • Synthetic food ingredient, cellulose gum, shifts the microbiota toward pro-inflammatory type. www.sciencedaily.com
    Microbiome

    Highly processed foods often contain ingredients such as emulsifiers, thickening agents, and stabilizers that improve texture and extend shelf life, although many of these compounds lack extensive safety testing. Consumption of highly processed foods has increased dramatically in recent decades (now representing over 57 percent of daily calories), alongside rates of inflammatory bowel disease and metabolic syndrome. Researchers investigated the effects of synthetic emulsifiers in the diet of healthy adults and found alterations in the gut microbiota associated with inflammatory disease.

    Carboxymethylcellulose, also known as cellulose gum, is a synthetic emulsifier (i.e., a compound that blends water and oil together) found in foods such as [fruit juices, processed dairy products, cooked fish products, breakfast cereals, and many other foods](fao.org/gsfaonline/additives/details.html?id=51). It was approved for use in food in the 1960s and determined to be safe because it is not absorbed in the digestive tract and is excreted in the feces mostly unchanged. However, recent evidence has shown a direct effect of emulsifiers on the gut microbiota that promotes inflammation and carcinogenesis. A more modern definition of safety that considers the effect of food additives on the health of the gut microbiota is needed.

    The authors performed a randomized, double-bllind controlled-feeding study with 16 healthy adults during which participants consumed a Western style diet without emulsifiers or with carboxymethylcellulose added. All participants consumed an emulsifier-free diet prepared in a metabolic kitchen for three days and then were admitted to an inpatient facility for 11 days where they were randomly assigned to continue the emulsifier-free diet or switch to a diet supplemented with 15 grams of carboxymethylcellulose. Participants answered questionnaires about their normal diet and provided blood, urine, and fecal samples at multiple times over the 14 study days. Finally, the investigators performed a sigmoid colonoscopy and took biopsy samples in order to directly sample the microbiota and intestinal environment.

    Carboxymethylcellulose consumption was associated with a significant increase in after-meal abdominal pain but was not associated with increased inflammation, gut permeability (i.e., leakiness), appetite, food consumption, or bloating. Participants consuming carboxymethylcellulose experienced a greater shift in the population of bacteria in the microbiota over the study period, losing overall diversity and specific species such as Faecalibacterium prausnitzii, a producer of beneficial short-chain fatty acids. Within three days of initiating carboxymethylcellulose consumption, beneficial fecal compounds such as short-chain fatty acids and essential amino acids were depleted even though the population of bacteria had yet to change substantially.

    The results support the growing concern over emulsifiers and other additives in processed foods and their effects on health.

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  • Antibiotics increase risk of some colorectal cancers, but protect against others. www.sciencedaily.com
    Cancer Microbiome Antibiotics

    Colorectal cancer is the third most common cancer and is responsible for approximately 600,000 deaths per year worldwide. Previous evidence has demonstrated an association between antibiotic use and colorectal cancer, which is troubling given rising antibiotic use; however, further research is needed to better understand this association. Authors of a recent report found that antibiotic use increased the risk of proximal colon cancer, but decreased the risk of rectal cancer in females.

    Colorectal cancers occur in three zones - the proximal colon, composed of the first two segments of the large intestine; the distal colon, composed of the second two segments of the large intestine; and the rectum. Most colon cancers occur in the proximal colon with distal colon and rectal cancers more common in males and in adults younger than 50 years. More than half of all colorectal cancer cases are attributable to modifiable risk factors such as smoking, diet, alcohol consumption, physical inactivity, and possibly medication.

    The gut microbiota is composed of the community of bacteria, archaea, fungi, and viruses that live in the human intestine, and its composition is highly sensitive to changes in lifestyle and use of medications. Antibiotics suppress the growth of beneficial gut bacteria in addition to pathogens, causing long term disruption of the gut ecosystem. Use of antibiotics may result in chronic inflammation and tumorigenesis due to overgrowth of pathogens such as Clostridium difficile; however, additional research is needed to understand the difference between classes of antibiotics and the effects of dose and duration.

    The authors collected data regarding colorectal cancer incidence and antibiotic use from the Swedish national population register. They compared data between more than 40,000 participants with colorectal cancer and more than 200,000 participants without colorectal cancer who were matched for age, sex, and home county. The researchers collected additional data about the participants, such as country of origin, socioeconomic status, and healthcare utilization. All data were collected between the years of 2005 and 2016.

    Moderate use of antibiotics (defined as use between 11 and 60 days) was associated with a 15 percent increased risk of colorectal cancer compared to no use. Very high use of antibiotics (defined as use greater than 180 days) was associated with a 17 percent increased risk compared to no use. However, these associations were no longer statistically significant when the investigators removed data regarding antibiotic use in the two years prior to cancer diagnosis. They removed this data to account for reverse causation, meaning use of antibiotics for illnesses caused by cancer. Excluding this data, the investigators found that moderate and very-high antibiotic use was significantly associated with proximal colorectal cancer. Surprisingly, antibiotic use decreased the risk of rectal cancer in females. This decreased risk was not present for proximal or distal colon cancers. Finally, the researchers found that the antibiotic classes quinolones, sulfonamides, and trimethoprims were most associated with proximal colon cancer, while nitrofurantoins, macrolides, and lincosamides were protective against rectal cancer.

    This large study demonstrates a relationship between increased antibiotic use and higher risk of proximal colon cancer. Surprisingly, some antibiotics may be protective against rectal cancer.

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  • Polyphenols prevent leaky gut syndrome. www.eurekalert.org
    Gut Microbiome Green Tea Polyphenol Intestinal Permeability Lipopolysaccharide

    Intestinal hyper-permeability, often referred to as “leaky gut,” is a condition in which the gaps between the cells that line the gut expand. These gaps allow pathogens such as bacteria or endotoxins (i.e., lipopolysaccharide, a major component of the cell membrane of gram-negative bacteria) to leak through the intestinal wall and pass directly into the bloodstream. Leaky gut is common among older adults, putting them at risk for many acute and chronic diseases. Findings from a recent study suggest that a polyphenol-rich diet reduces the risk of leaky gut in older adults.

    Polyphenols are bioactive compounds present in fruits and vegetables. Evidence suggests that polyphenols influence the composition and function of the gut microbiota, have beneficial effects on gut metabolism and immunity, and exert anti-inflammatory properties.

    The randomized, controlled, crossover trial involved 51 adults (60 years and older) who were living in a residential care facility and had elevated zonulin, a biomarker of impaired gut barrier function. Half of the participants followed their typical diet, but they substituted some items with polyphenol-rich foods while maintaining the same caloric and nutrient intake for eight weeks. The other half consumed their normal diet with no substitutions. After eight weeks, the two groups switched to the opposite diet. Participants underwent physical exams before, during, and after the study and provided blood and fecal samples for analysis.

    The polyphenol-rich foods included berries, blood oranges (and their juice), pomegranate juice, green tea, apples, and dark chocolate. On average, participants who ate the polyphenol-rich diet consumed 1391 milligrams of polyphenols per day, while those who ate a typical diet consumed only 812 milligrams of polyphenols per day. The study investigators noted that participants on the polyphenol-rich diet had higher levels of beneficial gut bacteria than those on the typical diet. They also noted that metabolites from cocoa and green tea polyphenols were associated with having higher levels of butyrate (a short-chain fatty acid that benefits gut health) and lower levels of zonulin. These changes improved overall gut health in the study participants, but the participants' age, baseline zonulin levels, and numbers of beneficial gut bacteria, especially those of the Porphyromonadaceae family, influenced the extent of benefit.

    These findings suggest that polyphenol-rich foods improve gut health and reduce the risk of leaky gut in older adults. They also underscore the importance of developing dietary habits that promote consumption of polyphenol-rich foods throughout the lifespan. For an easy way to get more polyphenols in your diet, try this polyphenol-rich smoothie.

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  • Intestinal microbiota diversity is degraded by the aging process, promoting disease. www.sciencedaily.com
    Gut Microbiome

    The gut microbiota, composed of the community of bacteria, archaea, fungi, and viruses that live in the human intestine, influences human health, aging, and disease. Previous research has demonstrated that microbial diversity, a measure associated with good health, decreases with age; however, these studies utilized stool samples to characterize the microbiota, which may not be representative of the entire gut. Findings of a new study utilizing intestinal samples demonstrate that the microbiota of the small intestine changes markedly with the aging process.

    Aging is associated with a wide range of physiological changes (such as increased inflammation, metabolic dysfunction) and a weakened immune system, and behavioral changes (such as increased medication use, reduced diet quality, and reduced physical activity). These changes reduce the number of species capable of surviving in the intestinal environment, reducing overall diversity. This less diverse microbiota is less able to crowd-out dangerous microbes such as coliform pathogens. While not all coliforms are dangerous, an increased abundance is associated with small intestinal bacterial overgrowth and inflammatory bowel disease. Centenarians, people who live beyond 100 years of age, exhibit higher microbiota diversity and higher capacity for producing beneficial microbial products such as short-chain fatty acids, demonstrating a relationship between microbiota quality and longevity.

    The researchers collected microbiota samples from 251 patients undergoing an upper endoscopy, an imaging procedure where a camera is used to view the esophagus, stomach, and small intestine. Participants ranged in age from 18 to 80 years old. Participants completed questionnaires about their medical history and gave a blood sample. The researchers measured blood lipids, glucose, insulin and other hormones, and inflammatory cytokines.

    The researchers found that the region of the gastrointestinal tract where diversity was most perturbed by age was the duodenum, the first portion of the small intestine that connects to the stomach. However, there were other variables that interfered with this statistical relationship. Duodenal microbial diversity decreased with chronological age but also with the number of medications used and the number of medical conditions reported. The authors interpreted this to mean that the microbiota becomes less diverse due to the aging process instead of simple chronological age. While some bacterial families remained stable over the lifespan, others such as the coliform genera Escherichia increased with chronological age and Klebsiella increased with the number of medications used.

    The authors concluded that the microbiota of the small intestine becomes less diverse due to the aging process, allowing the bloom of disease-promoting bacteria. Lifestyle interventions that improve the aging process by reducing the number of medical conditions and medications used may improve microbiota quality.

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  • Dietary fiber helps maintain muscle mass. onlinelibrary.wiley.com
    Microbiome Fiber

    Muscle mass decreases markedly with aging, compromising overall fitness and contributing to frailty, disability, and falls. Findings from a recent study suggest that dietary fiber helps reduce muscle mass losses associated with aging.

    Dietary fiber refers to the indigestible components of plant-based foods. It is classified as either soluble or insoluble. Soluble fiber, which is found in grains, nuts, seeds, legumes, and some vegetables and fruits, dissolves in water and may reduce blood glucose and cholesterol levels. Insoluble fiber, which is found in wheat bran, vegetables, and whole grains, does not dissolve in water. It promotes digestive health. Processed foods are typically low in fiber.

    According to the Dietary Guidelines for Americans, the recommendations for combined fiber intake vary according to age and sex. Women need between 22 and 28 grams of fiber per day, and men need between 28 and 34 grams per day. Most people living in the United States only get about half of the recommended amounts of fiber daily.

    The authors of the study drew on data collected over a seven-year period via the National Health and Nutrition Examination Survey. Study participants, which included more than 5,000 adults aged 40 years and older, provided information about their dietary intake and underwent physical exams (including the collection of blood and urine samples) to assess body composition, grip strength (a predictor of functional impairment and premature death), and metabolic health.

    They found that people whose diets were rich in dietary fiber had greater lean body mass, bone mineral content, and grip strength compared to those with low intake. People whose diets were rich in dietary fiber were also more likely to have lower body mass index, body fat, fasting glucose, fasting insulin, and HOMA-IR (a measure of insulin resistance) than those with low intake.

    These findings suggest that higher dietary fiber intake helps maintain muscle mass in older adults. Evidence indicates that sauna use improves muscle and bone mass, as well. Learn more about the health benefits of sauna use in this article by Dr. Rhonda Patrick.

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  • Prebiotics may help restore circadian rhythms. www.sciencedaily.com
    Microbiome Circadian Rhythm

    Circadian rhythms play critical roles in human health. Maintaining these rhythms can be challenging, especially for people who work night shifts or travel across multiple time zones. Findings from a new study suggest that prebiotics can help restore the body’s natural rhythms.

    Prebiotics are food components that support the maintenance of a healthy microbiota and create an environment that is conducive to its survival. Fructo-oligosaccharides, galacto-oligosaccharides, and trans-galacto-oligosaccharides are the most common prebiotics. Their fermentation by gut microbiota produces short-chain fatty acids, including lactic acid, butyric acid, and propionic acid. Many commonly consumed fruits and vegetables, such as apples, bananas, and legumes, contain prebiotics.

    The authors of the study fed rats either a prebiotic-enriched diet or a standard diet. After the rats had been on their respective diets for five weeks, the authors either flipped their light/dark schedules (roughly equivalent to flying across 12 time zones) or left them on a normal schedule once a week for eight weeks. They measured the animals' sleep, brain activity, core body temperature, and locomotor activity. They also collected fecal samples from the animals and identified the types and number of gut microbes present.

    The rats that ate the prebiotic-enriched diet resumed their normal sleep-wake cycles, core body temperature, and activity levels faster than the rats that ate the standard diet. The rats on the prebiotic diet also had greater abundance of several health-promoting microbes, including Ruminiclostridium 5, compared to those on the standard diet. Previous research indicates that Ruminiclostridium 5 is associated with improved sleep.

    These findings suggest that eating a diet rich in prebiotics can help restore normal circadian rhythms following disruption, such as would occur after working shifts or traveling. Learn more about the effects of shiftwork on human health in this episode featuring Dr. Satchin Panda.

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  • A high saturated fat diet increases heart disease marker, TMAO. news.vumc.org
    Microbiome Heart Disease Fat

    Heart disease is the number one cause of death in the United States, owing to a constellation of risk factors including a sedentary lifestyle, disrupted sleep patterns, stress, and poor diet. The average American adult consumes 29 grams of saturated fat per day (the amount in about four tablespoons of butter, four slices of pepperoni pizza, or 1.5 cups of ice cream), possibly contributing to heart disease risk through interactions with the gut microbiota. Findings of a new report link high saturated-fat diets to increased heart disease biomarkers among mice with high levels of E. coli bacteria.

    The gut microbiota, the community of bacteria, archaea, fungi, and viruses that lives in the human intestine, is highly influenced by changes in diet. Dietary fats that are not absorbed in the small intestine travel to the large intestine where microbes metabolize them. The same is true for other nutrients not absorbed by the gut, including choline, an essential nutrient found in high amounts in organ meats, egg yolks, and legumes. Choline is an important component of cellular membranes, a precursor for the production of neurotransmitters, and is incorporated into bile acids needed for the digestion of fats; however, some gut microbes convert choline into trimethylamine (TMA), which is absorbed by the intestine and converted to trimethylamine N-oxide (TMAO) in the liver. High serum levels of TMAO have been shown to increase the risk of major cardiovascular events such as heart attack and stroke by increasing the deposition of cholesterol in arterial walls (i.e., atherosclerosis).

    Clostridia and Enterobacteriaceae are the only two bacterial families common to the human gut microbiota that are known to produce TMAO, but only Enterobacteriaceae abundance is substantially increased on a high-fat diet. Oxygen content in the gastrointestinal tract decreases through the small and large intestines so that bacteria in the colon are mostly anaerobic (meaning they do not use oxygen for metabolism). This low oxygen environment is needed to promote the growth of more beneficial bacteria such as Clostridia and suppress the growth of more detrimental bacteria such as Enterobacteriaceae. In order to maintain this low oxygen environment, the mitochondria of colon cells must consume high levels of oxygen; however, a diet high in saturated fat may impair mitochondrial function, facilitating the growth of TMAO-producing bacteria and increasing heart disease risk.

    The investigators performed their experiments using two mouse strains with altered gut microbiota: mice that do not carry Enterobacteriaceae in their gut microbiota (E. negative) and germ-free mice, which are raised in a sterile environment and do not have a microbiota. They fed mice either a high-fat (60 percent of calories from fat) or low-fat (10 percent of calories from fat) diet for 10 weeks. The main source of fat in the high-fat diet was lard with casein protein, sugar, and micronutrients added. The researchers added a choline supplement to both the high-fat and low-fat diets one week before administering a single dose of a probiotic containing E. coli, a member of the Enterobacteriaceae family, to both E. negative and germ-free mice. All mice consumed their assigned diet for a total of 14 weeks. The researchers measured changes to epithelial cells in the colon including mitochondrial metabolism, inflammation, and cancer signatures.

    Both E. negative and germ-free mice that gained weight on the high-fat diet had increased inflammation and cancer signatures, suggesting some of the detrimental diet effects were independent of the microbiota. Germ-free mice on a low-fat diet had colon epithelial cells with appropriately low levels of oxygen; however, germ-free mice on a high-fat diet had colon epithelial cells with increased oxygen levels and reduced mitochondrial metabolism. Following E. Coli exposure, E. negative mice fed a high-fat diet supplemented with choline gained more weight and had higher levels of oxygen, inflammation, and signatures of cancer in their colons than E. negative mice fed a low-fat diet. These changes were associated with an increased concentration of fecal E. coli. In germ-free mice exposed to E. coli, a high-fat diet supplemented with choline significantly increased serum TMAO levels compared to all other groups.

    These results elucidate the mechanisms by which diets high in saturated fat may contribute to heart disease through interactions with choline metabolism by the gut microbiota. However, there are several important factors to consider in translating these results into relevant information for humans. Mouse diets often contain just one or two sources of fat such as lard and soybean oil, as was used in this study. Human diets contain a wider variety of fats, including various saturated and unsaturated fats. These diets also often contain high amounts of simple sugars, such as the sucrose and maltodextrin used in this study. The diet used in this study is also not representative of a standard human diet and limits the ability to distinguish between the effects of saturated fat and sugar. So, while animal studies are a vital foundation for human research, they should not be the basis for individual health recommendations. To hear Dr. Rhonda Patrick review the evidence on saturated fat and heart disease, listen to this episode of the FoundMyFitness podcast.

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  • Fecal microbiota transplantation from young mice reverses aging effects. www.sciencedaily.com
    Brain Aging Microbiome Immune System Microbes

    Declines in brain function are common with age owing to metabolic and immune alterations that include changes to the gut microbiota, the community of microorganisms that inhabit the intestines. While a diverse microbial community with many species of beneficial bacteria is associated with improved nutrition and reduced inflammation, older adults (especially residents of long-term care facilities) have perturbations in microbiota composition that increase the risk for cognitive decline and frailty. Findings of a report released this month show that fecal microbiota transplantation from young to aged mice reverses age-associated cognitive impairment.

    Fecal microbiota transplantation is a therapy in which microbes are isolated from the stool of a donor, processed, filtered, and administered to a recipient by nasogastric tube or enema. Previous research demonstrates the efficacy of fecal microbiota transplantation in treating infection with Clostridium difficile, a hospital-acquired infection that is difficult to treat with antibiotics, and a growing list of other diseases such as inflammatory bowel disease, metabolic syndrome, neurodevelopmental disorders (e.g., autism), and autoimmune diseases. Fecal microbiota transplantation improves health partially by increasing microbiota alpha diversity, meaning the number of species in an individual’s microbiota, also called “richess.” A microbiota with high richness is more likely to contain key beneficial species, such as those that produce neuroprotective short chain fatty acids.

    Given the wide range of diseases associated with gastrointestinal microbiota composition, its effects on aging are an area of intense interest. Prior investigations have demonstrated that transfer of the fecal microbiota from aged mice to young mice alters immunity, neurogenesis, and cognition; however, the consequence of fecal transplantation from young mice to aged mice is unknown.

    The investigators performed their experiment using young and aged male mice. They assigned aged mice to receive a fecal microbiota transplant from either a young mouse (the experimental group) or aged mouse (the control group). For further comparison, the researchers also assigned a group of young mice to receive a fecal microbiota transplant from another young mouse. Mice received the fecal microbiota transplant treatments once per day for three days, then twice weekly for four weeks. The mice completed a battery of tests to assess cognitive function. The researchers collected fecal samples in order to sequence the DNA of the microbiota and blood samples in order to measure hormones, cytokines, and other immune markers before and after the four weeks of treatment. Finally, they analyzed changes to gene expression and metabolism in the hippocampus, the brain region most-associated with age-related cognitive decline.

    At baseline, young and aged mice had distinctly different microbiota composition. Following four weeks of microbiota transplantation, young mice, aged mice receiving a young transplant, and aged mice receiving an aged transplant all had similar microbiota composition. Aged mice tended to have more over-reactive T cells, dendritic cells, and macrophages, especially in the lymph nodes that line the intestines. Aged mice also showed enlargement of microglia (the predominant immune cells in the brain), a common feature of neurodegenerative diseases. Microbiota transplantation from young mice reversed these age-related effects on brain and peripheral immunity. Amino acid metabolism in the hippocampus, which is necessary for neurotransmission and cognition, was impaired in aged mice, but restored following microbiota transplantation from young mice. Finally, the improved hippocampal metabolism in aged mice that received a young microbiota transplant translated to increased learning and long-term memory and reduced anxiety-related behaviors compared to aged mice receiving an aged microbiota transplant.

    These results reveal the potential benefits of fecal microbiota transplantation from young donors as a therapy to promote healthy aging.

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  • Fermented foods decrease inflammation and increase diversity of the gut microbiota. www.sciencedaily.com
    Gut Microbiome Probiotics IL-6

    The gut microbiota is composed of the community of bacteria, archaea, fungi, and viruses that live in the human intestine. Dietary components influence the composition and activity of the microbiota. For example, foods high in dietary fiber, such as whole grains and beans, and fermented foods, such as yogurt and sauerkraut, support an abundant and diverse gut microbiota, which is associated with lower disease risk. Authors of a report released this week investigated the effects of high-fiber and fermented foods on the gut microbiota and immune system.

    The authors recruited 36 healthy adult participants (average age, 52 years) who consumed little dietary fiber (fewer than 20 grams of fiber per day) and only one serving of fermented foods or less per day. They instructed half of the participants to add 20 grams or more of fiber per day to their baseline consumption. They instructed the other half of participants to consume six servings or more of fermented foods per day. Participants in both groups consumed their assigned diets for 10 weeks and recorded their food and beverage intake to assess adherence to study instructions. Participants also provided blood samples for the assessment of inflammation and fecal samples for the characterization of the gut microbiome at numerous time points throughout the study.

    A high-fiber diet did not reduce inflammation, but did alter the composition of the microbiota, increasing the abundance of bacteria known to metabolize dietary fibers, such as the genus Lachnospira. Higher fiber consumption also promoted greater secretion of enzymes associated with fiber metabolism and increased abundance of fiber metabolites, such as short chain fatty acids. A high-fermented food diet steadily increased microbiota diversity over time and decreased multiple markers of inflammation, including interleukin (IL)-6, IL-10, and IL-12b, among others.

    These results suggest that probiotics from fermented foods increase microbiota diversity and decrease inflammation. The authors noted that the lack of immunological response in participants consuming the high fiber diet may have been due to the short duration of the intervention.

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  • Eating protein at breakfast is best for growing muscle mass. pubmed.ncbi.nlm.nih.gov
    Microbiome Metabolism

    Dietary protein is essential for the growth of skeletal muscle, a process called hypertrophy. Circadian rhythms – the body’s 24-hour cycles of biological, hormonal, and behavioral patterns – modulate a wide array of nutritional and metabolic processes, including amino acid absorption and utilization. However, it is unclear how circadian rhythms affect muscle hypertrophy. A report published this month suggests that distributing dietary protein equally across meals is best for maintaining muscle mass.

    Circadian clocks located in the brain and other organs are driven by changes in the expression of genes such as Circadian locomotor output cycles kaput, commonly referred to as “Clock.” Mice that do not express the Clock gene do not experience day-night variations in metabolism, disrupting amino acid absorption by skeletal muscle. Amino acids are required for activation of genes such as the mammalian target of rapamycin (mTOR), which promotes autophagy, a system of disassembly and recycling of unnecessary or dysfunctional cellular components that is essential for hypertrophy.

    The investigators conducted a set of experiments in mice and an observational study in humans. They fed mice two meals per day containing either 11.5 percent or 8.5 percent protein for two weeks. Mice consumed these meals in three patterns of protein distribution: high protein at breakfast and low protein at dinner; equal protein at both meals; or low protein at breakfast and high protein at dinner. In a second experiment, the researchers fed mice branched chain amino acids, which are used in high concentrations by the body for building muscle, at breakfast or dinner. In both experiments, the researchers performed muscle overloading, which puts stress on muscles to encourage hypertrophy, similar to weight lifting in humans. They measured changes in muscle strength, muscle gene expression, plasma amino acid concentrations, plasma growth factor concentrations, and autophagy.

    All mice gained muscle mass in response to muscle overload; however, mice that consumed a high-protein breakfast and low-protein dinner had greater gains in muscle mass and rate of hypertrophy than mice that consumed a low-protein breakfast and high-protein dinner. Likewise, mice that consumed a branched chain amino acid supplement in the morning gained more muscle mass and had a higher rate of hypertrophy than mice that consumed the supplement at night. Mice that do not express the Clock gene did not experience gains in muscle mass or hypertrophy with early protein or branched chain amino acid intake, suggesting these gains were circadian-related.

    The researchers found that branched chain amino acid concentrations increased following a high-protein meal regardless of time, so these gains in hypertrophy were not due to circadian fluctuations in plasma amino acid concentrations. Likewise, insulin-like growth factor concentrations increased following a high-protein meal regardless of time and likely did not affect the rate of hypertrophy. However, the activation of autophagy in overloaded muscle was greater in mice that consumed a high-protein breakfast compared to a high-protein dinner, potentially contributing to a higher rate of hypertrophy.

    Next, researchers recruited 60 women who completed a questionnaire about their consumption of protein foods at breakfast, lunch, and dinner. The researchers classified participants as early protein consumers or late protein consumers based on their answers and measured the participants' body composition, physical activity, and grip strength.

    Muscle mass tended to be higher in participants who consumed protein earlier in the day, but this relationship was not statistically significant. Early protein consumers also had significantly greater grip strength and higher skeletal muscle index, which is the ratio of muscle mass in a person’s arms and legs to their height. These relationships remained significant even after taking diet and activity into account. Finally, skeletal muscle index increased as the percent of daily protein eaten at breakfast increased, meaning the more protein that was consumed in the morning, the greater the increase in skeletal muscle index.

    These results indicate that circadian genes drive day-night variation in muscle metabolism and protein utilization. Early protein consumption is more beneficial for growing and maintaining muscle than late protein consumption.

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  • A very-low-calorie diet increases harmful gut bacteria. www.sciencedaily.com
    Obesity Microbiome Fasting Antibiotics

    The gut microbiota is composed of the community of bacteria, archaea, fungi, and viruses that live in the human intestine and is unique to each individual. Diet can modulate the structure and function of the gut microbiota in ways that either increase or decrease disease risk. Findings of a new report detail the effects of a very-low-calorie diet on the gut microbiota, weight loss, and infection risk.

    Following the absorption of most macronutrients (carbohydrates, fats, and proteins) and micronutrients (vitamins and minerals) present in food in the small intestine, undigested food travels to the large intestine where microbes metabolize any remaining nutrients. The amount and type of food consumed in the diet directly affect the amount and type of microbes that can flourish in the large intestine. Consuming a wide variety of foods in the diet supports a wide variety of microbes, while restricting certain foods or restricting caloric intake may reduce the abundance and diversity of the microbiota, a risk factor for disease.

    The authors of the report recruited 80 females who had completed menopause and who had overweight or obesity. They randomized participants to complete a medically supervised weight-loss program or to maintain a stable weight for 16 weeks. Participants in the weight-loss program consumed a very-low-calorie diet (800 calories per day) for eight weeks, followed by four weeks of a conventional low-calorie diet and four weeks of a weight maintenance diet. The researchers sequenced DNA from the participants' gut microbiota to determine the number and type of microbes present. Finally, they collected gut microbiota samples from the baseline and 12-week timepoints from the participants who lost the most weight during the weight loss program. They transplanted these samples into germ-free mice, which lack a microbiota.

    Participants in the weight-loss program lost an average of 14 percent of their body weight (about 27 pounds) after 12 weeks. A very-low-calorie diet reduced the abundance and diversity of microbes in the gut, but these changes were reversed when participants returned to a normal diet. Microbiota samples from the participants in the very-low-calorie diet intervention were enriched in Clostridioides difficile, a gastrointestinal pathogen (commonly referred to as “C. diff.”). This increase was associated with a reduction in the production of bile acids, which aid in dietary fat digestion and are protective against gastrointestinal pathogens. Mice that received a microbiota transplant from the very-low-calorie diet timepoint lost significantly more body weight due to changes in microbiota structure and reduced nutrient absorption, compared to mice that received a microbiota transplant from baseline.

    This research highlights the importance of diet in the interplay between pathogenic and beneficial microbes in the gut microbiota.

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  • Intermittent fasting improves gut microbiota composition and markers of metabolic health. academic.oup.com
    Microbiome Fasting

    Intermittent fasting, a dietary practice in which individuals repeatedly, voluntarily, and heavily restrict food intake for approximately 16 to 24 hours, is a popular dietary intervention for weight loss and increased glucose tolerance. Some of the beneficial effects of intermittent fasting arise from its ability to modulate the gut microbiota, the community of microbes that live in the gastrointestinal tract. Findings of a recent report demonstrate the effect of intermittent fasting on microbiota structure and function in adults observing the Islamic faith-associated month of Ramadan.

    There are many health benefits attributed to intermittent fasting with the American Heart Association claiming that intermittent fasting may produce weight loss, reduce insulin resistance, and lower the risk for cardiometabolic diseases; however, the mechanisms that drive these benefits in humans are unclear. Experiments in mouse models have suggested that intermittent fasting produces changes in circadian biology and remodeling of the gut microbiota, but further research in humans is needed.

    The investigators recruited two cohorts of participants. The first cohort consisted of healthy young adult males (average age, 19 years) who expressed intention to fast during the month of Ramadan according to Islamic law, which dictates 30 days of fasting from dawn to sunset (approximately 16 hours in this study). These participants provided stool samples for microbiome analysis and blood for the measurement of metabolic makers before the start of Ramadan, 15 days into the month, and at the end of the month. The second cohort consisted of healthy middle-aged adults (average age, 40 years). Some participants in this cohort practiced Ramandan fasting and some did not. Participants in this cohort also provided stool samples for microbiome analysis and blood samples for the measurement of metabolic markers. The researchers collected this data at the beginning and end of the month of Ramadan and 30 days afterward.

    The researchers found that microbiota diversity increased among participants practicing Ramadan-associated intermittent fasting compared to non-fasting participants. This diversity was specifically associated with increased abundance of the bacterial families Lachnospiraceae and Ruminococcaceae. Lachnospiraceae is capable of producing the short-chain fatty acid butyrate, which is a known promoter of metabolic health. Increased abundance of Lachnospiraceae was associated with beneficial changes in liver enzymes. Microbiota composition returned to normal 30 days following the end of Ramadan.

    The authors concluded that intermittent fasting alters the composition of the gut microbiota. Specifically, fasting increased the abundance of the butyrate-producing Lachnospiraceae family, which may explain some of the beneficial physiological effects of intermittent fasting.

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  • Excess sugar intake in early life impairs memory in adulthood via changes in the gut microbiota. www.sciencedaily.com
    Brain Diet Microbiome Memory Development

    A healthy gut microbiota is important for cognitive function at any age, but especially during development. Poor dietary quality in early life (i.e., consuming excess sugar) negatively impacts the composition of the gut microbiota and impairs cognitive functioning; however, the mechanisms that drive these changes are unclear. Authors of a new report detail the functional relationship between detrimental gut microbes and hippocampal memory in rats exposed to excess sugar during adolescence.

    Germ-free mice, which are born and raised in a sterile environment, demonstrate impaired brain development compared to mice with a normal gut microbiota. This suggests that microbiota composition in early life may impact cognitive function in adulthood. Dietary strategies that minimize sugar intake may improve microbiota quality and maximize developmental potential in children and adolescents.

    The investigators conducted a two-part experiment in rats. In the first experiment, they fed sugar-sweetened water or plain water to juvenile rats for 11 weeks. They sequenced bacterial DNA from the rats' fecal samples to measure changes in the gut microbiota. In the second experiment, the researchers treated juvenile rats with antibiotics or a placebo for seven days. Then they treated one half of the antibiotic group with a bacterial culture of Parabacteroides distasonis and Parabacteroides johnsonii, while the other half received a placebo. In both experiments, rats completed a series of tests to measure memory function in adulthood. Finally, the researchers measured gene expression in the hippocampus, one the major memory centers of the brain.

    Adult sugar-fed rats exhibited impaired performance on memory tasks associated with the hippocampus, but not other memory centers. The authors discovered that sugar consumption led to an increase in Parabacteroides bacteria in the gut that correlated with impaired hippocampal function. When antibiotic-treated rats were given Parabacteroides distasonis and Parabacteroides johnsonii as a supplement in adolescence, they exhibited similar deficits in memory performance in adulthood as sugar-fed rats. Sugar consumption altered the expression of genes associated with neurotransmitter signaling, while Parabacteroides treatment altered genes associated with metabolic function, neurodegenerative disease, and dopamine signaling.

    The authors of this comprehensive report concluded that early-life dietary factors like sugar consumption impact brain development and may impair memory via changes in the gut microbiota.

    Link to full study.

    Learn more about sugar and its effects on the brain and body in this podcast featuring Dr. Rhonda Patrick.

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  • Fasting "jump starts" dietary strategies to improve symptoms of metabolic syndrome. www.sciencedaily.com
    Microbiome Fasting Blood Pressure

    Metabolic syndrome is a constellation of conditions that includes high blood pressure, high blood glucose, excess abdominal fat, and abnormal cholesterol levels. People with metabolic syndrome are at higher risk for developing heart disease, stroke, and type 2 diabetes. Findings from a new study suggest that fasting “jump starts” dietary strategies to improve symptoms of metabolic syndrome.

    The “Western diet,” also known as the Standard American Diet, is rich in processed foods, red meat, high-fat dairy products, and added sugars. It plays contributing roles in the development of metabolic syndrome. Conversely, the DASH diet – Dietary Approaches to Stop Hypertension – is rich in fruits, vegetables, whole grains, nuts, legumes, low-fat dairy products, and dietary fiber, and low in red meat and sugar-sweetened beverages. It is one of the most commonly prescribed and successful dietary patterns for managing high blood pressure and other aspects of metabolic syndrome.

    Gut health also plays a role in development of metabolic syndrome. In fact, an imbalance in the number of harmful versus helpful microbes in the gut, a condition known as dysbiosis, drives many disease states. Fasting and caloric restriction induce changes in the gut microbiota to promote health.

    The three-month intervention study included 71 adults between the ages of 50 and 70 years who had high blood pressure and metabolic syndrome. Half of the participants followed a modified DASH diet alone, while the other half followed a combined fasting and modified DASH diet. The modified DASH diet was a plant-based dietary program that was low in sodium, fat, and sugar. The combined fasting/DASH diet started with two calorie-restricted vegan days (no more than 1,200 calories per day), followed by a five-day liquid fast that included vegetable juices and vegetable broth (300 to 500 calories per day). Upon completion of the fast, the participants followed the modified DASH plan. Both groups received approximately 50 hours of nutrition counseling, cooking lessons, and lifestyle coaching on exercise and stress management.

    The authors of the study measured the participants' blood pressure and other markers of metabolic health, including body weight. They also measured immune cells and assessed the microbial makeup of the participants' gut microbiota.

    Blood pressure (and the need for blood pressure medications) and bodyweight decreased among the participants following the fasting/DASH diet. The gut microbial composition of the participants following the fasting/DASH diet changed markedly during fasting, adopting a profile that was rich in microbes involved in short-chain fatty acid production, mucin degradation, and nutrient utilization. These changes in microbial composition reverted partially upon completion of the three-month DASH diet. The fasting/DASH diet also induced changes in immune cell populations, which were reversed when the participants ended their fast. Notably, fasting reduced the number of proinflammatory immune cells, whereas regulatory T cells increased. The participants who followed the DASH diet alone did not experience changes in their gut microbiota or immune cell populations.

    These findings suggest that combining periodic fasting with a modified DASH diet improves blood pressure, body weight, and metabolic health in adults with metabolic syndrome better than the DASH diet alone. The participants in this study were of Caucasian-European background, potentially limiting the application of its findings. Further study is needed in a more heterogenous population.

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  • Leaky gut decreases the beneficial effects of dietary polyphenol compounds in older adults. pubs.acs.org
    Gut Microbiome Polyphenol Intestinal Permeability

    Polyphenols are a group of bioactive compounds found in plant-based foods that have beneficial effects in the body. Bacteria in the human gut break down polyphenols into smaller compounds to increase their absorption. Authors of a recent study aimed to measure the relationship between gut health and the absorption of beneficial polyphenols in older adults.

    As humans age, the quality of the population of microbes that comprise the gut microbiota decreases, leading to poor gut barrier integrity and causing contents of the gut to leak into the bloodstream, a condition commonly referred to as “leaky gut.” This leaking of toxins, viruses, and bacteria is associated with increased inflammation and disease risk. In addition to causing a leaky gut, poor microbiota quality may decrease the beneficial effects of polyphenol-rich plant foods.

    The authors tested the effects of a polyphenol-rich diet in 51 adults (greater than 60 years of age) residing in an assisted living setting. Participants consumed either the normal menu prepared by their facility for eight weeks or a menu that included three servings of polyphenol-rich fruits, teas, and cocoa for eight weeks and then switched to the opposite diet. The researchers collected blood samples to measure serum zonulin, a marker of gut barrier integrity, and urine samples to analyze polyphenol metabolite content before and after each diet period.

    Overall, serum zonulin decreased following eight weeks of a polyphenol-rich diet, meaning that gut barrier integrity improved. Participants who started the trial with better gut barrier integrity had a significantly greater increase in blood levels of polyphenol metabolites compared to participants with leakier guts. The metabolites found in the group with greater gut barrier integrity were microbial-derived, suggesting these participants had a more health-promoting gut microbiota.

    Based on these results, the authors hypothesize that changes in the gut microbiota damage the gut barrier and cause a subsequent reduction in the absorption of dietary polyphenol compounds. They conclude that personalized diet plans could be effective for managing leaky gut in older adults.

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  • Fecal microbiota transplant improves immunotherapy response among melanoma patients. www.eurekalert.org
    Cancer Microbiome

    Fecal microbiota transplant is a therapeutic strategy that involves transfer of feces from a donor to a recipient. The goal of fecal transplant is to restore the microbial balance in the gut of the recipient as a means to improve health. A new study demonstrates that fecal microbiota transplant improves the response to immunotherapy among melanoma patients.

    Immunotherapy exploits the immune system to treat cancer. One type of immunotherapy, anti–programmed cell death protein 1 (PD-1) therapy is beneficial in treating patients with advanced melanoma. However, gut microbial composition influences anti–PD-1 efficacy in preclinical models and cancer patients. About 40 percent of melanoma cancer patients do not respond to immunotherapy.

    The authors of the study performed fecal microbiota transplants and anti-PD-1 immunotherapy (a drug called pembrolizumab) in melanoma patients who had not responded to all other therapies, including anti-PD-1. The fecal microbiota donors were people who demonstrated robust responses to anti-PD-1 immunotherapy.

    More than one-third of the patients who received the transplants responded favorably to the anti-PD-1 immunotherapy despite having not responded before the transplant. The types of gut microbes associated with response to anti–PD-1 increased, as did activation of CD8+ T cells. The number of interleukin-8–expressing myeloid cells (which are involved in immunosuppression) decreased. These findings suggest that fecal microbial transplant is a viable option for improving the response to immunotherapy among melanoma patients and underscore the need for greater understanding of the role the gut microbiota play in immune function.

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  • Microbiome signatures distinguish adults with depression from healthy counterparts. www.the-scientist.com
    Microbiome Depression

    The gut and brain communicate with each other through a bidirectional signaling pathway called the gut-brain axis, which may be dysregulated in depression. Key elements of this pathway are the tens of trillions of bacteria, viruses, and fungi that comprise the intestinal microbiota. Diagnosis of depression relies heavily on clinical evaluation instead of measurement of biomarkers, often leading to misdiagnosis. Authors of a new report aimed to identify which specific microbial and metabolic biomarkers are altered in patients with depression.

    Changes to the microbes that live in the gut or the metabolites that these microbes consume and produce may be responsible for the development and severity of depression. Previous research has demonstrated that transplanting the microbiota of patients with depression into germ-free mice can induce depressive symptoms in these animals.

    The study involved 311 participants between the ages of 18 and 65 years, roughly half of whom had been diagnosed with major depressive disorder. The participants completed testing that included submission of a fecal sample to characterize the gut metagenome (sum of all DNA and RNA) and metabolome (sum of all proteins). They also completed surveys to assess depression severity, diet quality, and lifestyle habits.

    The authors reported large and consistent disturbances in amino acid metabolic metabolism in participants with depression. These disturbances may disrupt the balance of neurotransmitters, such as dopamine, glutamate, and GABA. Most of the bacterial species that were increased in patients with depression belong to the genera Bacteroides, which the authors believe is responsible for the increase in inflammatory markers found in the depression group. The authors also reported an association between select viruses in the gut and metabolites associated with depression.

    Utilizing both metagenomic and metabolic data enabled the authors to identify strong associations between altered amino acid metabolism in the gut and depression. The authors noted that these findings are preliminary and require further investigation in a larger, more diverse sample.

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  • Antibiotic use disrupts sleep/wake cycles in mice www.sciencedaily.com
    Microbiome Sleep

    Many adults struggle with daytime sleepiness and nighttime insomnia, impairing memory, mood, and focus. Several factors regulate sleep and wake activities, including central and peripheral circadian rhythms and timing of meals. These rhythms also regulate the diurnal activities of the gut microbiota. New research reports that antibiotics, which can alter the gut microbial population, may disrupt normal sleep cycles in mice due to changes in neurotransmitters.

    The human gut is an important site for the production and metabolism of neurotransmitters like serotonin. Neurotransmitters in the gut regulate digestive processes, communicate with the brain directly through the enteric nervous system, and interact with the microbiome. Serotonin is important for regulating sleep/wake cycles, and too little serotonin may decrease sleep quality.

    The scientists gave mice water containing broad spectrum antibiotics for four weeks to deplete their gut microbiota or normal drinking water. They used implantable electrodes to collect detailed sleep pattern data in the mice and measured concentrations of metabolites in the animals' guts and feces.

    The authors reported significant alterations in metabolites related to vitamin, amino acid, and neurotransmitter metabolism in mice whose microbiota had been depleted with antibiotics. These mice exhibited less time in deep sleep during the day (when these nocturnal animals should be sleeping) and more time in deep sleep during the night. They also experienced frequent transitions between rapid eye movement (REM) sleep and non-REM deep sleep, an indicator of decreased sleep quality. The authors suggested this may have been caused by lower levels of serotonin in the gut due to depletion of vitamin B6, a necessary cofactor for producing serotonin.

    This research could have important implications for human health. The authors noted that other research has demonstrated the ability of some prebiotics (fiber and nutrients that are beneficial for the gut microbiota) to improve sleep in humans.

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  • Gut microbial conversion of glucosinolates to isothiocyanates is highly variable in humans. cancerpreventionresearch.aacrjournals.org
    Gut Microbiome Sulforaphane Isothiocyanates Myrosinase Glucoraphanin

    Glucoraphanin, a precursor to sulforaphane, is a type of glucosinolate found primarily in broccoli and kale. Its conversion to sulforaphane requires myrosinase, an enzyme co-located within the leaves, stems, and other components of the plants in which it is found. Cooking temperatures inactivate myrosinase, effectively preventing isothiocyanate conversion and allowing unhydrolyzed glucosinolates to pass into the gut. In humans, myrosinase-producing gut bacteria can convert these glucosinolates to their cognate isothiocyanates. Findings from a 2012 study indicate that microbial conversion of glucosinolates to isothiocyanates is highly variable.

    Previous research has demonstrated that sulforaphane administration promotes uniformly high urinary excretion of dithiocarbamate metabolites, accounting for as much as 90 percent of the administered sulforaphane over a 24-hour period. Dithiocarbamate levels in urine serve as a biomarker of glucosinolate intake.

    The study involved two dissimilar groups of people: rural Han Chinese and racially mixed Baltimoreans. The participants abstained from cruciferous vegetable consumption for three days prior to the beginning of the study. They had not taken antibiotics for two weeks prior. Each of the participants kept a food diary, provided their medical history, and kept track of their bowel activity. The participants took a glucoraphanin-rich broccoli sprout extract that provided 200 micromoles of glucoraphanin in water. The authors of the study collected urine samples from 8 a.m. to 4 p.m. and from 4 p.m. until 8 a.m. on the following morning.

    They found that microbial-induced conversion of glucoraphanin to sulforaphane is highly variable (ranging from 1 to 40 percent of dose) and subject to interindividual differences in gut bacteria populations. As such, conversion is distinguished by “high converters” – people with high elimination profiles, and “low converters”– those with low elimination profiles. The authors of the study identified no demographic factors that affected conversion efficiency, but they did note that conversion of glucoraphanin to dithiocarbamate was greater during the day.

    Watch this clip in which Dr. Jed Fahey describes some of the factors that influence the conversion of myrosinase-driven conversion of glucoraphanin to sulforaphane.

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  • Fecal microbiota transplantation resets gut microbial composition of infants born via C-section to a healthier profile. www.sciencedaily.com
    Microbiome Pregnancy

    Establishment of the healthy infant gut begins at birth when the infant is exposed to the microbial milieu of the mother’s vaginal canal. Consequently, the gut microbial profile of infants delivered by Caesarean section differs markedly from those delivered vaginally and may contribute to greater risk for disease in both early and later life. Evidence from a new study suggests that fecal microbiota transplantation can reset the gut microbial composition of infants born via Caesarean section to a healthier profile.

    The study involved seven pregnant women (scheduled to deliver infants via Caesarean section at 37 weeks' gestation) and their infants. Each of the infants received a diluted fecal microbiota transplant derived from their own mother’s stool, delivered in 5 milliliters of their first human milk feeding. The authors of the study assessed the infants' inflammatory markers for two days in the maternity ward. Each of them women breastfed their infants for two months after the fecal microbial transplant.

    During a three-month follow-up period, the infants remained healthy and showed no adverse effects. The fecal microbial composition of the treated Caesarean section-born infants showed remarkable similarity to that of vaginally born infants.

    The results of this small, proof-of-concept study suggest that fecal microbiota transplantation has potential as a means of resetting the microbial composition of infants born via Caesarean-section to a healthier profile. The authors of the study cautioned that careful clinical and microbiological screening was essential to prevent serious harm to the infants.

    Another player in the establishment of the infant gut microbiota is nutrition. Breastfeeding promotes a healthy gut microbial composition to confer lifelong health. Learn more about breast milk and breastfeeding in our overview article.

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  • Fecal microbiota transplant from aged mice donors impairs cognitive function in younger mice recipients. www.sciencedaily.com
    Microbiome

    The gut-brain axis, a bidirectional signaling pathway between the gastrointestinal tract and the nervous system, plays key roles in human health. Key elements of this pathway are the tens of trillions of microbes that comprise the intestinal microbiota, the composition of which likely changes with age. A new study suggests that transplanting fecal microbiota from aged mice donors impairs cognitive function in younger mice recipients.

    Aging is the collective physiological, functional, and mental changes that accrue in a biological organism over time. It is the primary risk factor for many chronic conditions, including cognitive decline. Changes in the gut related to reduced barrier function and microbiota composition play key roles in the aging process.

    The authors of the study transplanted fecal microbes from aged mice into young (adult) mice. Then they subjected the young mice to a battery of spatial learning and memory tests involving mazes and escape tunnels.

    They found that the young mice that received fecal microbial transplants from the aged mice showed marked deficits in spatial learning and memory capacity. These changes were mediated via altered expression of proteins involved in maintaining neuroplasticity and neurotransmission in the hippocampus – a region of the brain involved in learning and memory. The transplantation did not induce deficits in locomotion or induce anxiety-like behaviors, common features in older mice.

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  • Soluble fiber supplementation improves body weight and metabolism in adults with overweight and obesity. academic.oup.com
    Obesity Microbiome

    More than two-thirds of adults living in the United States have overweight or obesity. Having overweight or obesity increases a person’s risk of developing metabolic disorders such as diabetes. Findings from a 2017 review indicate that dietary fiber supplementation reduces body weight and improves metabolism in adults with overweight or obesity.

    Dietary fiber is classified as either soluble or insoluble. Soluble fiber, which is found in grains, nuts, seeds, legumes, and some vegetables and fruits, dissolves in water and may reduce blood glucose and cholesterol levels. Insoluble fiber, which is found in wheat bran, vegetables, and whole grains, does not dissolve in water. It promotes digestive health. Processed foods are typically low in fiber.

    According to the Dietary Guidelines for Americans, the recommendations for combined fiber intake vary according to age and sex. Women need between 22 and 28 grams of fiber per day, and men need between 28 and 34 grams per day. Most people living in the United States only get about half of the recommended amounts of fiber on a daily basis.

    The authors of the review analyzed the findings of 12 randomized controlled trials involving more than 600 participants enrolled in interventions lasting between two and 17 weeks. Their analysis revealed that supplementation elicited beneficial effects on the study participants, with modest but notable improvements observed in BMI, body weight, body fat, fasting glucose, and fasting insulin, compared with the effects of placebo treatments. The authors of the review noted that the types of soluble fiber and dosages varied considerably across the 12 studies, however.

    These findings suggest that soluble fiber supplementation is a promising strategy for improving weight and metabolic health in people with overweight or obesity and supports efforts to increase fiber content of processed foods.

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  • Antibiotics alter signaling pathways that influence behavioral development. medicalxpress.com
    Microbiome

    Many factors influence human emotions and behavior. A key player in their regulation is the gut microbiome – the community of microbes that resides in the intestinal tract. Findings from a new study show indicate that antibiotic use early in life alters neuropeptide signaling pathways that influence behavioral development.

    Antibiotics are often prescribed to treat ear infections, respiratory illness, and diarrhea in children. They are among the most commonly prescribed drugs among children living in the United States.

    Neuropeptide signaling pathways are the means by which neurons communicate with each other. Three primary pathways modulate human behavior, namely the opioid, oxytocin, and vasopressin systems. The opioid system modulates social behavior, mediates physical pain, and participates in social attachment and other aspects of behavior and emotion. Oxytocin and vasopressin play roles in social cognition, pair bonding, and sexual behaviors.

    The authors of the mouse study allocated the animals to one of two groups to receive either drinking water containing a cocktail of antibiotics or drinking water alone for three weeks. The antibiotic cocktail contained ampicillin, vancomycin, neomycin, metronidazole, and amphotericin-B – a mixture that is known to eradicate the gut bacteria without killing the mice.

    The mice that received the antibiotics demonstrated altered neuropeptide gene expression in the frontal cortex and brain stem regions, which might explain the altered behavior observed in mice that received the same cocktail in other experiments. These findings demonstrate that antibiotic use in early life may alter behavior and underscores the importance of efforts to reduce the overprescribing of antibiotics.

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  • Enzymes produced by common oral bacteria show promise for treating celiac disease. www.sciencedaily.com
    Microbiome Gluten Autoimmunity

    Celiac disease is an autoimmune disorder characterized by an inflammatory response to eating gluten. An estimated 1 percent of people worldwide have celiac disease, but diagnosing the condition is difficult, often due to vague, seemingly minor, or even absent symptoms. Consequently, the epidemiology of celiac disease is best described by the “iceberg model.” That is, for every diagnosed case of celiac disease (the visible part of the iceberg), roughly five cases remain undiagnosed (the hidden part of the iceberg). Findings from a new study indicate that enzymes from Rothia bacteria may be useful in treating people who have celiac disease.

    Gluten is a composite of two proteins found in wheat, barley, and rye. During normal digestion, enzymes break proteins down into groups of amino acids called peptides. Most peptides can be broken down further, taken up in the intestine, and then transported to the body’s tissues for use. However, gluten cannot be broken down by the digestive enzymes and can provoke an immune response in susceptible people, causing celiac disease.

    Rothia bacteria are regular inhabitants of the mouth and respiratory tract. They rarely cause infections, except in some immunocompromised people. Rothia bacteria can break down the peptides in gluten that provoke the immune response.

    The authors of the study extracted subtilisins, a type of enzyme found in the membrane of Rothia bacteria, and monitored the enzymes' activity. They also monitored the activity of food-grade subtilisins, enzymes used to make natto, a fermented soybean product. They found that both types of bacterial subtilisins effectively broke down the immunogenic peptides present in gluten, demonstrating that subtilisins from Rothia bacteria or other food-grade bacteria might be useful in treating celiac disease.

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  • Gut microbiota altered in type 2 diabetes. www.eurekalert.org
    Microbiome Diabetes Metformin

    Type 2 diabetes affects more than 400 million people worldwide. Some studies have demonstrated that the microbes that inhabit the human gut contribute to the pathophysiology of type 2 diabetes, but the use of anti-diabetes drugs like metformin may have confounded the results due to their impact on the gut. Findings from a new study suggest that the overall makeup of the gut microbial population in people with type 2 diabetes is altered.

    The authors of the study profiled the microbiota of two groups of participants with varying degrees of glucose tolerance, ranging from normal to impaired (prediabetes) to having untreated type 2 diabetes. One group included 189 people who had isolated impaired fasting glucose, 178 who had isolated impaired glucose tolerance, 75 who had combined glucose intolerance, and 46 who had type 2 diabetes but had not begun treatment. A second group included 523 people with normal glucose tolerance, 226 at low risk for developing type 2 diabetes, and 297 at high risk.

    They found that the composition of the gut microbiota among the participants with any degree of glucose intolerance differed markedly from that of the participants with normal glucose tolerance. The participants with prediabetes and diabetes were more likely to have fewer butyrate-producing bacteria in their guts. Butyrate is a short-chain fatty acid produced during bacterial fermentation in the human colon. It has wide-ranging effects on human physiology. The authors also noted that the composition of the gut microbiota can serve as a biomarker for diabetes.

    These findings suggest that altering the gut microbiota could serve as a means to prevent the development of type 2 diabetes.

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  • Consumption of probiotics and prebiotics has beneficial effects on the gut-brain axis and mental health. www.sciencedaily.com
    Gut Microbiome Depression

    The gut-brain axis, a bidirectional signaling pathway between the gastrointestinal tract and the nervous system, is a critical component of mental health. Key elements of this pathway are the tens of trillions of bacteria, viruses, and fungi that comprise the intestinal microbiota. A recent review suggests that consuming probiotics and prebiotics has beneficial effects on the gut-brain axis and mental health.

    Probiotics are live microbes that, when consumed in the diet or in supplemental form, confer a health benefit to the host. Prebiotics are food components that support the maintenance of a healthy microbiota and create an environment that is conducive to its survival. Prebiotic fermentation by gut microbiota produces short-chain fatty acids, including lactic acid, butyric acid, and propionic acid.

    The authors of the review selected seven studies for their analysis. Each of the studies investigated the efficacy of probiotics and/or prebiotics in treating anxiety and/or depression.

    Their analysis revealed that the participants in the studies showed significant improvements in their anxiety and/or depressive symptoms. Furthermore, participants who had common comorbidities associated with their mental health conditions (such as irritable bowel syndrome), saw additional benefits due to the purported beneficial effects of probiotics/prebiotics on gut health. The authors noted several limitations of the various studies, including sample sizes, study durations, and the failure to assess long-term effects and remission risks.

    These findings suggest that probiotics and prebiotics have beneficial effects on mental health. Larger, more comprehensive studies are needed to confirm their usefulness.

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  • Lower salt intake improves gut microbial health and blood pressure. www.eurekalert.org
    Microbiome Blood Pressure Salt

    Sodium is an essential nutrient that plays key roles in nerve signaling, muscle contraction, and fluid balance. The average person living in the United States consumes approximately 3,400 milligrams of sodium per day in table salt, roughly 50 percent higher than recommended intake. Getting too much sodium can increase a person’s risk for high blood pressure, heart disease, and stroke. Findings from a new study suggest that lower salt intake increases blood levels of short-chain fatty acids in people with high blood pressure.

    Short-chain fatty acids are fatty acids that contain fewer than six carbons in their chemical structure. They are produced by gut microbes during the fermentation of dietary fiber and reflect the overall health of the gut microbiome. Short-chain fatty acids play critical roles in many aspects of health, including the maintenance of healthy blood pressure.

    The randomized, double-blind, placebo-controlled cross-over trial involved 145 men and women (average age, 50 years) with untreated high blood pressure. The participants were asked to limit their sodium intake to 2,000 milligrams per day for six weeks. During that time, the participants took either nine sodium tablets (providing 10 mmol sodium per tablet) or a placebo daily and then crossed over to receive the other tablets for another six weeks. The low-sodium diet plus the slow sodium tablets represented typical sodium intake, and the low-sodium diet plus the placebo represented a low-sodium intake. The authors of the study measure levels of short-chain fatty acids in the participants' blood and monitored their blood pressure.

    They found that reducing sodium intake increased the levels of short-chain fatty acids in the participants' blood, and these increases were associated with reduced blood pressure and improvements in arterial compliance, especially among women. These findings suggest that lower salt intake can have beneficial effects on blood pressure and support public health recommendations for reducing salt intake.

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  • Gut bacteria use flavonoids to prime the body's immune response and protect against influenza. Press release: https://www.sciencedaily.com/releases/2017/08/170803141048.htm
    Gut Microbiome Virus COVID-19

    Gut bacteria process bioactive plant-based dietary compounds and, in turn, produce metabolites not synthesized by their human hosts. Many of these metabolites influence human health by regulating physiological processes such as nutritional homeostasis, energy expenditure, and immunity. A 2017 study demonstrated that microbial metabolites produced from flavonoids modulate the body’s response to influenza infection.

    Flavonoids are bioactive compounds present in a variety of fruits and vegetables. More than 4,000 flavonoids have been identified in the human diet. When gut bacteria called Clostridium orbiscindens break down flavonoids, they produce a metabolite known as desaminotyrosine (DAT). DAT helps the body produce interferon, a signaling molecule that activates the immune system.

    The authors of the rodent study gave mice DAT for seven days and then infected them with influenza. The mice continued to receive DAT for 14 days post-infection. A control group of mice received no DAT.

    The mice that received the DAT exhibited lower levels of viral RNA and less epithelial damage and apoptosis in their lungs. They also experienced less weight loss and were less likely to die from their infection than control mice. Interestingly, if mice were given DAT two days post-infection, they had worse outcomes than the mice who received DAT before infection, suggesting that DAT primed the immune system for an appropriate response to an immune challenge.

    These findings suggest that dietary compounds can boost immune function and highlight the importance of regular consumption of these protective compounds to prime the immune system.

    Press release: https://www.sciencedaily.com/releases/2017/08/170803141048.htm

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  • Alterations in gut microbial fermentation modulate the efficacy of exercise for diabetes prevention and management. www.cell.com
    Exercise Microbiome Insulin Carbohydrates

    Public health officials and healthcare providers commonly recommend exercise as a strategy to prevent or manage the symptoms of type 2 diabetes, but the cardiometabolic response to exercise is variable. Whereas exercise improves insulin sensitivity and promotes cardiovascular health in most adults (responders), exercise exerts a paradoxical effect in which metabolic health is compromised in as many as 69 percent of adults (non-responders). Findings from a recent study suggest the variable effects of exercise in people with prediabetes may be due to alterations in gut microbial fermentation.

    Microbial fermentation is the process by which gut bacteria break down and utilize carbohydrates in the gut. The metabolites produced during microbial fermentation include short-chain fatty acids and branched-chain amino acids, which are absorbed and used by the host. Short-chain fatty acids improve symptoms of diabetes, but branched-chain amino acids have the converse effect

    The study involved both humans and mice. The human study included 39 overweight or obese men with prediabetes who were between the ages of 20 and 60 years. Participants were randomized to engage in either sedentary activities or supervised exercise training for 12 weeks. They maintained their usual diet throughout the study period. At the end of the 12-week period, fecal microbial samples from two of the participants (responders and non-responders) were transplanted into obese mice.

    The results demonstrated that the responders' microbiota displayed increased production of short-chain fatty acids, whereas those of the non-responders displayed increased production of brain-chain amino acids. Fecal microbial transplantation from responders mimicked the effects of exercise on alleviation of insulin resistance in the mice, but fecal transplants from the non-responders did not. These findings may augment and facilitate clinical management of symptoms of diabetes.

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  • Gut bacteria may alter the aging process of the human brain through the production of butyrate www.sciencedaily.com
    Brain Gut Aging Microbiome Neuron Fatty Liver Neurons Neurogenesis Butyrate

    The gut microbiota is a complex and dynamic population of microorganisms that is subject to change throughout an individual’s lifespan in response to the aging process. Findings from a new study demonstrate that altering the gut microbial population may alter the aging process of the human brain.

    The authors of the study transplanted gut microbiota samples from healthy young or old mice into young germ­-free mice. Eight weeks after the transplant, the mice that received microbial samples from the old mice demonstrated increased neurogenesis – the process of forming new neurons – in the hippocampus region of their brains.

    Further analysis revealed that these mice also had larger numbers of butyrate-producing microbes in their colons. Butyrate, a short-chain fatty acid, is produced during bacterial fermentation in the human colon and has wide-ranging effects on human physiology. In this study, butyrate was associated with an increase in growth factors and subsequent activation of key longevity signaling pathways in the livers of the recipient mice. When butyrate alone was given to the recipient mice it promoted neurogenesis, as well.

    The findings from this study may have relevance for dietary interventions to maintain or improve brain health.

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  • Fecal samples from people with colorectal cancer transplanted into mice caused precancerous lesions. www.pasteur.fr
    Cancer Microbiome

    More than half of all colorectal cancers are sporadic, or nonhereditary. A key driver in the development of sporadic colorectal cancer is dysbiosis – an imbalance in the type and number of microbes that typically reside in the human gut. A recent study found that colorectal dysbiosis induced epigenetic changes and promoted the development of precancerous lesions in the guts of fecal transplant recipient mice.

    The authors of the study transplanted fecal samples from healthy individuals or from individuals with sporadic colorectal cancer into the guts of 136 germ-free mice. Seven and 14 weeks after the transfer, the mice were assessed for dysbiosis, epigenetic changes in their colonic cell DNA, and the presence of aberrant crypt foci (ACF) – precancerous lesions associated with the development of colorectal cancer.

    The mice that received fecal transplants from people with colorectal cancer had dysbiosis and exhibited higher numbers of ACF compared to those that received transplants from healthy people. The mice also exhibited hypermethylation of specific genes. Hypermethylation is a type of epigenetic modification of DNA that drives gene expression and is associated with increased risk for developing ACF.

    Based on these findings, the study authors then analyzed the blood of 1,000 people who were scheduled for routine colonoscopy, looking for the presence of specific colonic bacteria (dysbiosis) and indications of hypermethylation of the same genes identified in the mice. They found that hypermethylation of these genes correlated with sporadic colorectal cancer incidence, which could potentially serve as a diagnostic marker for the disease.

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  • Plant-Derived Exosomal MicroRNAs Shape the Gut Microbiota www.cell.com
    Gut Microbiome

    Summary from cited work: The gut microbiota can be altered by dietary interventions to prevent and treat various diseases. However, the mechanisms by which food products modulate commensals remain largely unknown. We demonstrate that plant-derived exosome-like nanoparticles (ELNs) are taken up by the gut microbiota and contain RNAs that alter microbiome composition and host physiology. Ginger ELNs (GELNs) are preferentially taken up by Lactobacillaceae in a GELN lipid-dependent manner and contain microRNAs that target various genes in Lactobacillus rhamnosus (LGG). Among these, GELN mdo-miR7267-3p-mediated targeting of the LGG monooxygenase ycnE yields increased indole-3-carboxaldehyde (I3A). GELN-RNAs or I3A, a ligand for aryl hydrocarbon receptor, are sufficient to induce production of IL-22, which is linked to barrier function improvement. These functions of GELN-RNAs can ameliorate mouse colitis via IL-22-dependent mechanisms. These findings reveal how plant products and their effects on the microbiome may be used to target specific host processes to alleviate disease.

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  • Animal study demonstrates fungus C. albicans can cross the blood-brain barrier and may promote neurodegenerative disease, such as Alzheimer's www.sciencedaily.com
    Brain Alzheimer's Parkinson's Aging Microbiome Blood-Brain Barrier

    A common type of fungus, Candida albicans, was shown to cross the blood-brain barrier and trigger an inflammatory response in the brain that results in memory impairment (mouse study).

    These findings raise the possibility that fungal infections may play a role in the development of chronic neurodegenerative disorders, such as Alzheimer’s disease. Dr. Dale Bredesen talks about this is the recent podcast episode I did with him.

    Check that out here: https://www.foundmyfitness.com/episodes/dale-bredesen

    From the article:

    “We thought that yeast would not enter the brain, but it does,” Corry said. “In the brain, the yeast triggered the activity of microglia, a resident type of immune cell. The cells became very active ‘eating and digesting’ the yeast. They also produced a number of molecules that mediated an inflammatory response leading to the capture of the yeasts inside a granule-type structure inside the brain. We called it fungus-induced glial granuloma, or FIGG.”

    The mice cleared the yeast infection in about 10 days; however, the microglia remained active and the FIGGs persisted well past this point, out to at least day 21. Intriguingly, as the FIGGs formed, amyloid precursor proteins accumulated within the periphery and amyloid beta molecules built up around yeast cells captured at the center of FIGGs. These amyloid molecules are typically found in plaques that are the trademark of Alzheimer’s disease. […] Intriguingly, as the FIGGs formed, amyloid precursor proteins accumulated within the periphery and amyloid beta molecules built up around yeast cells captured at the center of FIGGs. These amyloid molecules are typically found in plaques that are the trademark of Alzheimer’s disease.

    […]

    “The results prompted us to consider the possibility that in some cases, fungi also could be involved in the development of chronic neurodegenerative disorders, such as Alzheimer’s, Parkinson’s and multiple sclerosis. We are currently exploring this possibility.”

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  • Cellular stress with changes in microbial profile promotes colorectal cancer development www.sciencedaily.com
    Cancer Microbiome Inflammation Protein Toll-Like Receptors

    Activation of ATF6, a regulator of ER (Endoplasmatic Reticulum) stress, combined with changes in cecal microbial profile, promoted colon adenoma formation.

    [Abstract]

    Methods: We analyzed data from 541 patients with CRC in the TCGA database for genetic variants and aberrant expression levels of unfolded protein response genes. Findings were validated in a cohort of 83 patients with CRC in Germany. We generated mice with intestinal epithelial cell-specific expression of the active form of ATF6 (nATF6IEC) from 2 alleles (homozygous), mice with expression of nATF6IEC from 1 allele (heterozygous), and nATF6IECfl/fl mice (controls). All nATF6IEC mice were housed under either specific-pathogen free or germ-free conditions. Cecal microbiota from homozygous nATF6IEC mice or control mice was transferred into homozygous nATF6IEC mice or control mice. nATF6IEC mice were crossed with mice with disruptions in the myeloid differentiation primary response gene 88 and toll-like receptor adaptor molecule 1 gene (Myd88/TRIF knock-out mice). Intestinal tissues were collected from mice and analyzed by histology, immunohistochemistry, immunoblots, gene expression profiling of unfolded protein response and inflammatory genes, array-based comparative genome hybridization, and 16S rRNA gene sequencing.

    Results: Increased expression of ATF6 was associated with reduced disease-free survival times of patients with CRC. Homozygous nATF6IEC mice developed spontaneous colon adenomas at 12 weeks of age. Compared to controls, homozygous nATF6IEC mice had changes in the profile of their cecal microbiota, increased proliferation of intestinal epithelial cells, and loss of the mucus barrier—all preceding tumor formation. These mice had increased penetration of bacteria into the inner mucus layer and activation of STAT3, yet inflammation was not observed at the pre-tumor or tumor stages. Administration of antibiotics to homozygous nATF6IEC mice greatly reduced tumor incidence, and germ-free housing completely prevented tumorigenesis. Analysis of nATF6IEC MyD88/TRIF knock-out mice showed that tumor initiation and growth required MyD88/TRIF-dependent activation of STAT3. Transplantation of cecal microbiota from nATF6IEC mice and control mice, collected before tumor formation, caused tumor formation in ex–germ-free nATF6IEC mice.

    Conclusions: In patients with CRC, ATF6 was associated with reduced time of disease-free survival. In studies of nATF6IEC mice, we found sustained intestinal activation of ATF6 in the colon to promote dysbiosis and microbiota-dependent tumorigenesis.

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  • More Evidence for Gut-Brain Link in Alzheimer's Disease www.medscape.com
    Nutrition Alzheimer's Gut Microbiome

    “Three key findings emerged: First, lower serum concentrations of primary bile acids synthesized in the liver from cholesterol were significantly associated with worse cognitive function, decreased hippocampal volume, and decreased brain glucose metabolism.

    Second, higher serum concentrations of secondary bile acids produced in the gut by bacteria were significantly associated with higher CSF phosphorylated tau and CSF total tau levels, as well as larger brain structural atrophy and decreased brain glucose metabolism.

    Third, higher serum concentrations of ratios of bacterially produced secondary bile acids to primary bile acids were significantly associated with lower CSF Aβ1-42 values, larger brain structural atrophy, and decreased brain glucose metabolism."

    https://www.medscape.com/viewarticle/899956

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  • Role of dietary transition metals on host microbiota and risk of disease www.gutmicrobiotaforhealth.com
    Nutrition Gut Diet Microbiome Metabolism Immune System Micronutrients Iron Protein

    Transition metals are required cofactors for many proteins that are critical for life, and their concentration within cells is carefully maintained to avoid both deficiency and toxicity. To defend against bacterial pathogens, vertebrate immune proteins sequester metals, in particular zinc, iron, and manganese, as a strategy to limit bacterial acquisition of these necessary nutrients in a process termed “nutritional immunity.” In response, bacteria have evolved elegant strategies to access metals and counteract this host defense. In mammals, metal abundance can drastically shift due to changes in dietary intake or absorption from the intestinal tract, disrupting the balance between host and pathogen in the fight for metals and altering susceptibility to disease. This review describes the current understanding of how dietary metals modulate host-microbe interactions and the subsequent impact on the outcome of disease.

    https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(18)30262-2

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  • Exercise training-induced modification of the gut microbiota persists ..... www.tandfonline.com
    Exercise Gut Microbiome Inflammation

    Full Title: Exercise training-induced modification of the gut microbiota persists after microbiota colonization and attenuates the response to chemically-induced colitis in gnotobiotic mice

    Summary: Exercise reduces the risk of inflammatory disease by modulating a variety of tissue and cell types, including those within the gastrointestinal tract. Recent data indicates that exercise can also alter the gut microbiota, but little is known as to whether these changes affect host function. Here, we use a germ-free (GF) animal model to test whether exercise-induced modifications in the gut microbiota can directly affect host responses to microbiota colonization and chemically-induced colitis. Donor mice (n = 19) received access to a running wheel (n = 10) or remained without access (n = 9) for a period of six weeks. After euthanasia, cecal contents were pooled by activity treatment and transplanted into two separate cohorts of GF mice. Two experiments were then conducted. First, mice were euthanized five weeks after the microbiota transplant and tissues were collected for analysis. A second cohort of GF mice were colonized by donor microbiotas for four weeks before dextran-sodium-sulfate was administered to induce acute colitis, after which mice were euthanized for tissue analysis. We observed that microbial transplants from donor (exercised or control) mice led to differences in microbiota β-diversity, metabolite profiles, colon inflammation, and body mass in recipient mice five weeks after colonization. We also demonstrate that colonization of mice with a gut microbiota from exercise-trained mice led to an attenuated response to chemical colitis, evidenced by reduced colon shortening, attenuated mucus depletion and augmented expression of cytokines involved in tissue regeneration. Exercise-induced modifications in the gut microbiota can mediate host-microbial interactions with potentially beneficial outcomes for the host. KEYWORDS: exercise, microbiome, gut, microbiota, colitis, germ-free, transplant, colonization inflammation, voluntary wheel running

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  • Disruption of maternal gut microbiota during gestation alters offspring microbiota and immunity | Microbiome | Full Text microbiomejournal.biomedcentral.com
    Microbiome Immune System Pregnancy Antibiotics

    Early life microbiota is an important determinant of immune and metabolic development and may have lasting consequences. The maternal gut microbiota during pregnancy or breastfeeding is important for defining infant gut microbiota. We hypothesized that maternal gut microbiota during pregnancy and breastfeeding is a critical determinant of infant immunity. To test this, pregnant BALB/c dams were fed vancomycin for 5 days prior to delivery (gestation; Mg), 14 days postpartum during nursing (Mn), or during gestation and nursing (Mgn), or no vancomycin (Mc). We analyzed adaptive immunity and gut microbiota in dams and pups at various times after delivery.

    Results - In addition to direct alterations to maternal gut microbial composition, pup gut microbiota displayed lower α-diversity and distinct community clusters according to timing of maternal vancomycin. Vancomycin was undetectable in maternal and offspring sera, therefore the observed changes in the microbiota of stomach contents (as a proxy for breastmilk) and pup gut signify an indirect mechanism through which maternal intestinal microbiota influences extra-intestinal and neonatal commensal colonization. These effects on microbiota influenced both maternal and offspring immunity. Maternal immunity was altered, as demonstrated by significantly higher levels of both total IgG and IgM in Mgn and Mn breastmilk when compared to Mc. In pups, lymphocyte numbers in the spleens of Pg and Pn were significantly increased compared to Pc. This increase in cellularity was in part attributable to elevated numbers of both CD4+ T cells and B cells, most notable Follicular B cells.

    Conclusion - Our results indicate that perturbations to maternal gut microbiota dictate neonatal adaptive immunity.

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  • Gut microbiota resilience as an emerging measure of health - Gut Microbiota for Health www.gutmicrobiotaforhealth.com
    Gut Microbiome Biomarkers Immune System

    Although gut microbiota profiles differ remarkably between healthy individuals, several features have been suggested to define a “healthy gut microbiome”. First of all, our gut microbiota can be understood, in many cases, to be redundant given that many bacterial species have similar functions. Furthermore, a healthy gut microbiome is temporally stable and resistant to perturbations and, over time, is more similar to itself than to that of another healthy person. Finally, a healthy gut microbiome is resilient, which means that it returns to a healthy state after a perturbation. For example, after antibiotic treatment, our gut microbiota usually recovers to its previous state a few weeks or months later. As such, a plausible definition of microbial health does not comprise a single static state, but rather a dynamic equilibrium. Meanwhile, when a perturbation stimulus becomes chronic and leads to an altered stable gut microbiome that causes harm to the host, this is called dysbiosis. Also see the following for detailed discussion of microbiome as emerging biomarker of health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3577372/

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  • Intermittent fasting increased gut bacteria diversity, reduced inflammation, demyelination, and axonal damage in multiple sclerosis (MS) animal model. www.cell.com
    Gut Microbiome Fasting Multiple Sclerosis Autoimmunity

    Intermittent fasting (every other day) increased gut bacteria diversity and reduced inflammation, demyelination, and axonal damage in multiple sclerosis (MS) animal model. A small pilot trial in humans with MS showed many similar changes to the gut microbiome and blood adipokines such as leptin. The effects of fasting on immune cells included a reduction of pro-inflammatory IL-17-producing T cells and increased numbers of T regulatory cells which prevent autoimmunity.

    The small pilot trial in humans showed increased bacteria richness in species that have previously been shown to promote T regulatory cell accumulation in the colon.

    Interestingly, this study did what is called a metagenomic analysis and found that the ketone pathway was enhanced in the gut microbiome by intermittent fasting. This is super interesting because bacteria in the gut normally produce short chain fatty acids and ketones from fermentable fiber but suggests that the gut microbiome regulates its own ketone body metabolism during fasting!

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  • People with multiple sclerosis increased beneficial gut bacteria & induced an anti-inflammatory immune response after supplementation with a probiotic www.ncbi.nlm.nih.gov
    Gut Microbiome Probiotics Multiple Sclerosis Autoimmunity

    A pilot study finds people with multiple sclerosis (and healthy controls) increased several species of beneficial gut bacteria and induced an anti-inflammatory immune response after supplementation with a strong, high CFU probiotic for 3 months.

    Multiple sclerosis patients also displayed a decrease in a type of immune cell called myeloid-derived dendritic cells which play a role in suppressing immune cells that prevent autoimmunity (called T-regulatory cells). Larger studies are needed to replicate these findings as well as investigate whether the probiotic supplementation has any effect on clinical symptoms.

    To my knowledge, there are exactly three brands that have this type of formulation of high CFU probiotic that seems to have a strong and growing body of clinical, published evidence: • VSL#3 (the original formulation) • Visbiome (a newer brand used in this study that is supposed to be substantially similar) • Vivomixx (European branded Visbiome)

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  • The gut microbiome and kynurenine pathway/tryptophan metabolism www.frontiersin.org
    Microbiome Serotonin Metabolic Syndrome

    [Abstract]

    The gut microbiota influences the health of the host, especially with regard to gut immune homeostasis and the intestinal immune response. In addition to serving as a nutrient enhancer, L-tryptophan (Trp) plays crucial roles in the balance between intestinal immune tolerance and gut microbiota maintenance.

    Recent discoveries have underscored that changes in the microbiota modulate the host immune system by modulating Trp metabolism. Moreover, Trp, endogenous Trp metabolites (kynurenines, serotonin, and melatonin), and bacterial Trp metabolites (indole, indolic acid, skatole, and tryptamine) have profound effects on gut microbial composition, microbial metabolism, the host’s immune system, the host-microbiome interface, and host immune system–intestinal microbiota interactions. The aryl hydrocarbon receptor (AhR) mediates the regulation of intestinal immunity by Trp metabolites (as ligands of AhR), which is beneficial for immune homeostasis. Among Trp metabolites, AhR ligands consist of endogenous metabolites, including kynurenine, kynurenic acid, xanthurenic acid, and cinnabarinic acid, and bacterial metabolites, including indole, indole propionic acid, indole acetic acid, skatole, and tryptamine. Additional factors, such as aging, stress, probiotics, and diseases (spondyloarthritis, irritable bowel syndrome, inflammatory bowel disease, colorectal cancer), which are associated with variability in Trp metabolism, can influence Trp–microbiome–immune system interactions in the gut and also play roles in regulating gut immunity.

    This review clarifies how the gut microbiota regulates Trp metabolism and identifies the underlying molecular mechanisms of these interactions. Increased mechanistic insight into how the microbiota modulates the intestinal immune system through Trp metabolism may allow for the identification of innovative microbiota-based diagnostics, as well as appropriate nutritional supplementation of Trp to prevent or alleviate intestinal inflammation. Moreover, this review provides new insight regarding the influence of the gut microbiota on Trp metabolism. Additional comprehensive analyses of targeted Trp metabolites (including endogenous and bacterial metabolites) are essential for experimental preciseness, as the influence of the gut microbiota cannot be neglected, and may explain contradictory results in the literature.

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  • A certain type of bacteria found in the small intestine can travel to other organs and initiate the production of auto-antibodies and inflammation. www.sciencedaily.com
    Gut Microbiome Inflammation Autoimmunity

    A certain type of bacteria found in the small intestine (E. gallinarum) can travel to other organs and initiate the production of auto-antibodies and inflammation which both play a role in autoimmune disease.

    A certain species called Enterococcus gallinarum, was found to spontaneously “translocate” outside of the gut to lymph nodes, the liver, and spleen in mice and was found in cultured liver cells of healthy people, and in livers of patients with autoimmune disease.

    Most bacteria in the gut is in the large intestine near the colon and not small intestine. Typically, certain phyla and classes of bacteria that crop up on a low fiber diet and these bacteria possess flagella that allows move or “swim” up the intestines and penetrate the small intestine (where they are not supposed to be). This is often referred to as small intestine bacterial overgrowth.

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  • Impact of non-antibiotic drugs on the microbiome www.nature.com
    Microbiome Drug

    [Abstract]

    A few commonly used non-antibiotic drugs have recently been associated with changes in gut microbiome composition, but the extent of this phenomenon is unknown. Here, we screened more than 1,000 marketed drugs against 40 representative gut bacterial strains, and found that 24% of the drugs with human targets, including members of all therapeutic classes, inhibited the growth of at least one strain in vitro. Particular classes, such as the chemically diverse antipsychotics, were overrepresented in this group. The effects of human-targeted drugs on gut bacteria are reflected on their antibiotic-like side effects in humans and are concordant with existing human cohort studies. Susceptibility to antibiotics and human-targeted drugs correlates across bacterial species, suggesting common resistance mechanisms, which we verified for some drugs. The potential risk of non-antibiotics promoting antibiotic resistance warrants further exploration. Our results provide a resource for future research on drug–microbiome interactions, opening new paths for side effect control and drug repurposing, and broadening our view of antibiotic resistance.

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  • Two types of gut bacteria found to fuel the growth of colon cancer in humans. www.nytimes.com
    Cancer Gut Microbiome

    The bacteria penetrate through the gut barrier and release compounds that damage DNA and inflame colon cells. This can both induce colon cancer and/or allow precancerous cells to grow into cancer.

    The strains of bacteria are Bacteroides fragilis and a strain of E. coli. Not everyone has these two types of bacteria but those that do are thought to have gotten them during childhood.

    This study analyzed 25 tumor samples taken from people with familial adenomatous polyposis and found the two bacterial species present in large quantities.

    Animals were then given a cancer-causing agent to cause mutations in DNA of colon cells. There were few or no tumors until the animals were transplanted with both strains of the gut bacteria…this caused tumor growth.

    It is unclear how people acquire these two strains of bacteria early in life or how to get rid of them. But this is the first step in understanding a complex interaction between certain species of gut bacteria and colon cancer.

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  • Glycemic responses to bread may depend more on the composition of the gut microbiome than the composition of bread (white vs. whole wheat). www.cnn.com
    Nutrition Microbiome Inflammation Sugar

    A small trial including 20 people were given either sourdough whole-grain bread or refined white bread to eat for one week. After a two-week break, each participant switched bread types for another week.

    The study found very surprising results. Consuming either bread type improved cholesterol levels and improved markers of inflammation. The glycemic response was also dependent on the person’s gut microbiome composition and not bread type. This was surprising considering that fiber slows digestion and normally lowers the glycemic response. The bacterial strains that affected the glycemic response were Coprobacter fastidiosus and Lachnospiraceae bacterium, the latter of which has previously been associated with the development of type 2 diabetes.

    More research needs to be done before any definitive conclusions can be made but this study just highlights the potential importance of the gut microbiome in the glycemic response to food. Here is a link to the full study.

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  • VSL#3 improved HDL, insulin sensitivity, LDL, atherogenic factors, and inflammation www.ncbi.nlm.nih.gov
    Gut Obesity Microbiome Insulin Resistance Cholesterol Omega-3 Inflammation Microbes VSL#3 Insulin Triglycerides

    FTA

    … a clinical trial in 60 overweight (BMI > 25), healthy adults, aged 40-60 years. After initial screening, the subjects were randomized into four groups with 15 per group. The four groups received, respectively, placebo, omega-3 fatty acid, probiotic VSL#3, or both omega-3 and probiotic, for 6 weeks. […] The probiotic (VSL#3) supplemented group had a significant reduction in total cholesterol, triglyceride, LDL, and VLDL and had increased HDL (P < 0.05) value. VSL#3 improved insulin sensitivity (P < 0.01), decreased hsCRP and favorably affected the composition of gut microbiota. Omega-3 had a significant effect on insulin sensitivity and hsCRP but had no effect on gut microbiota. The addition of omega-3 fatty acid with VSL#3 had a more pronounced effect on HDL, insulin sensitivity and hsCRP. Table showing statistics of the study.

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  • 30% of infants gut bacteria may come from the mother’s breast milk and another 10% has been traced to the skin around the mother’s nipple. www.the-scientist.com
    Gut Microbiome Probiotics Pregnancy Prebiotics

    30% of infants gut bacteria may come from the mother’s breast milk and another 10% has been traced to the skin around the mother’s nipple. There is a specific type of prebiotic found exclusively in breastmilk called human milk oligosaccharides that have been shown to set up the early infant microbiome. The bacteria around the skin of the nipple also appears to be important for seeding the infant microbiome. While this study did not examine health consequences of breastfeeding, other studies have found that it is important for immune system development and may protect against obesity.

    To learn more about the role of breastfeeding in setting up the infant microbiome and more generally about how to have a healthy microbiome during adulthood listen to (or watch) my podcast (video/audio) with microbiome experts Drs. Justin and Erica Sonnenburg. YouTube: https://youtu.be/gOZcbNw7sng iTunes: https://itunes.apple.com/us/podcast/sonnenburgs-on-how-gut-microbiota-interacts-our-bodies/id818198322?i=1000351247766&mt=2

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  • Disruption of the gut microbiome and gut barrier may be the primary cause of age-related inflammation which accelerates the aging process. www.sciencedaily.com
    Gut Microbiome Inflammation Fiber Carbohydrates

    This study showed that older mice have imbalances in the bacterial composition in the gut which then leads to the breakdown of the gut barrier and the release of bacterial products that trigger inflammation and impair immune function.

    We know that inflammation has recently been identified as the key driver of aging in 4 different age groups including elderly, centenarians, semi-supercentenarians, and supercentenarians. We also know that lack of fermentable fiber starves the gut microbiome and causes the bacteria to eat the gut barrier which is made of carbohydrates and this results in the breakdown of the barrier and inflammation.

    For more information on why fermentable fiber is so important for the gut microbiome and what good sources are…listen to my podcast with gut experts, Drs. Justin and Erica Sonnenburg. YouTube: https://youtu.be/gOZcbNw7sng

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  • Sulforaphane (found in broccoli sprouts) causes 20% fat loss by changing gut bacteria & increasing mitochondria in fat in mice. www.sciencedaily.com
    Gut Obesity Microbiome Metabolism Inflammation Sulforaphane Fatty Liver NRF2 Endotoxemia Lipopolysaccharide Visceral Fat

    Sulforaphane from broccoli sprouts causes 20% visceral fat loss by changing gut bacteria and increasing mitochondria in fat in mice. The mice fed sulforaphane also lowered fatty liver and reduced blood glucose levels. Sulforaphane reduced inflammation by decreasing a species of bacteria in the gut that is responsible for producing endotoxin, which is a major source of inflammation. Also, sulforaphane increased the levels of UCP1, which is responsible for increasing mitochondrial biogenesis (the generation of new mitochondria) in fat (called browning of fat). The browning of fat increases fat metabolism and can lead to fat loss. There have been human studies showing that sulforaphane decreases inflammatory biomarkers and improves blood glucose levels. It will be interesting to see future studies looking at these two new functions of sulforaphane in humans. For more information check out my video on sulforaphane or my podcast with Dr. Jed Fahey, who discovered broccoli sprouts are the best source of sulforaphane. Sulforaphane video: https://youtu.be/zz4YVJ4aRfg Sulforaphane podcast: https://youtu.be/Q0lBVCpq8jc

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  • Clinical trial shows whole grains modestly increase good gut bacteria, lower inflammatory gut bacteria, improve immune cells. www.sciencedaily.com
    Microbiome Inflammation Immune System Fiber Gluten

    New clinical trial shows that people that were given whole grains had a modest improvement in a good type of gut bacteria, modestly lowered inflammatory gut bacteria, and modestly increased memory T cells after 6 weeks compared to those given refined grains. Since this study compared gut bacteria, inflammatory biomarkers, and immune cells in people given whole grains versus refined grains it is difficult to draw any conclusions about whole grains compared to no grains. However, there have been other intervention trials that have shown whole grains lowered inflammatory biomarkers possibly through their effect on the microbiome. Also, this intervention trial was only 6 weeks which may also account for the modest effect on the microbiome. Things are probably much more complicated and have a lot to do with gene polymorphisms (which affect an individual’s glucose response), gut health, gluten sensitivity, and other factors. I do not think any absolute conclusions can be drawn from this study but still interesting to think about.

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  • Supplemental probiotics for 12 weeks improved cognition in Alzheimer's patients & also lowered inflammatory markers. www.sciencedaily.com
    Brain Alzheimer's Gut Microbiome Inflammation Probiotics Behavior Insulin Triglycerides Dopamine Norepinephrine Acetylcholine

    The probiotics also lowered triglycerides, VLDL, and markers of insulin resistance. There was no cognitive improvement in the placebo group.

    The participants took 2 billion Bifidobacterium bacteria per day, which is a pretty small quantity of probiotics. It is likely that the probiotics are working through multiple mechanisms such as lowering inflammation and increasing neurotransmitters. Other studies have shown that gut bacteria are able to modulate the levels of GABA, norepinephrine, serotonin, dopamine, and acetylcholine through the gut-brain axis.

    I spoke with the gut experts, Drs. Justin and Erica Sonnenburg, about the importance of the gut microbiome in human health and the various foods (ie. fermentable fiber and other prebiotics) that provide our gut bacteria with the food they need to thrive. Here is the interview (also available on iTunes and Sticher): https://www.youtube.com/watch?v=gOZcbNw7sng

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  • People with the highest fiber intake had ~80% greater chance of living long & healthy life out of all other dietary factors looked at. www.sciencedaily.com
    Gut Aging Microbiome Inflammation Depression Immune System Carbohydrates

    other factors including total carbohydrate intake, glycemic index, glycemic load, and sugar intake. Successful aging was defined as including an absence of disability, depressive symptoms, cognitive impairment, respiratory symptoms, and chronic diseases including cancer, coronary artery disease, and stroke.

    The gut is a major source of inflammation and also the major regulator of the immune system. Fermentable fiber feeds the beneficial bacteria in the gut which then prevents them from being forced to cannibalize the gut barrier (which causes inflammation) and it allows them to produce signaling molecules (short chain fatty acids) which make the immune system better. Also, many foods that contain fiber such as vegetables and fruits also have many important micronutrients and other plant compounds that play a role in successful aging. For more on the importance of fiber in successful aging watch my interview with the authors of The Good Gut, Drs. Justin and Erica Sonnenburg: https://youtu.be/gOZcbNw7sng

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