Gut
Episodes
In this clip, Dr. Rhonda Patrick discusses dietary strategies to improve gut health, including fermented foods, probiotics, and glutamine supplementation.
Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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In this clip, Dr. Rhonda Patrick discusses dietary strategies to improve gut health, including fermented foods, probiotics, and glutamine supplementation.
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Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Rhonda Vitamin D Gut Ketosis Insulin Resistance Fasting Sulforaphane Intestinal Permeability NRF2 Urolithin ADr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Intestinal Permeability: the Bacterial link to Aging, Brain Barrier Dysfunction & Metabolic DisorderIntestinal Permeability Alzheimer's Gut Heart Disease Inflammation Depression Blood-Brain Barrier LipopolysaccharideDr. Patrick's keynote: compromised intestinal barrier affects human health—cardiometabolic function, neurological health, behavior, and more.
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In this clip, Dr. Dominic D'Agostino gives his thoughts on eating an all-meat diet and weighs in on whether it is optimal to eat a diet devoid of fiber.
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In this clip, Rich Roll and Dr. Rhonda Patrick discuss the differences between nitrites, nitrates, and nitrosamines and their cancer-causing potential.
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In this clip, Dr. Satchin Panda talks about how time-restricted eating affects leaky gut and systematic inflammation.
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In this clip, Dr. Eran Elinav discusses the intestinal barrier's important role in absorbing nutrients while keeping out pathogens.
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Rhonda Exercise Gut Microbiome Sleep Heart Disease Diabetes Omega-3 Fasting Pregnancy Melatonin Vaccine Iron Gluten COVID-19 Breast Milk Wearable TechnologyDr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Rhonda Alzheimer's Gut Sleep Omega-3 Inflammation Vaccine Vitamin K Autism Sauna COVID-19 NAD+ SupplementsDr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Milk Fat Globule Membranes (MFGMs) in breast milk affect development of gut, brain, and intelligence ClipIn this clip, Dr. Rhonda Patrick describes the structure and function of milk fat globule membranes in breast milk.
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In this clip, Dr. Rhonda Patrick describes the multifaceted roles of HMOs in breast milk.
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In this clip, Dr. Dominic D'Agostino discusses the importance of an individualized approach when considering glutamine supplementation.
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In this clip, Dr. Dominic D'Agostino discusses how the body adapts to a ketogenic diet and the possible impacts on age-related chronic diseases.
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In this clip, Dr. Dominic D'Agostino describes the benefits of including fiber from diverse vegetable sources, both cooked and raw, within a ketogenic diet plan.
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In this clip, Dr. Dominic D'Agostino and Dr. Rhonda Patrick discuss the ketogenic diet and its implications for gut health.
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In this clip, Dr. Peter Attia and Dr. Rhonda Patrick discuss how a healthy digestive tract interacts with the immune system to curb inflammation.
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In this clip, Dr. Erica Sonnenburg describes the important role of human milk oligosaccharides in establishing a healthy gut in an infant.
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Rhonda Vitamin D Brain Alzheimer's Gut Microbiome Sleep Fasting Autophagy Sauna Vegetarian Weight Loss Supplements Ketogenic Diet Wearable Technology Blood TestDr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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Rhonda Nutrition Alzheimer's Cancer Gut Fasting Circadian Rhythm Pregnancy Vaccine Autophagy Sulforaphane Time-Restricted Eating Breast Milk Supplements Ketogenic DietDr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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A modest change on the "micronutrient smoothie" that also talks about the beneficial compounds that don't qualify as micronutrients.
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Performance Brain Alzheimer's Cancer Gut Aging Ketosis Insulin Resistance Podcast Cholesterol Inflammation Immune System InsulinDr. Peter Attia discusses dietary strategies to promote longevity and optimal performance.
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Biomarkers Vitamin D Nutrition Exercise Alzheimer's Gut Microbiome Performance Insulin Resistance Podcast CholesterolJim Kean is the CEO of National Pro Grid League (NPGL) and founder of WellnessFX.
Topic Pages
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Blood-brain barrier
Microbial metabolites from the gut modulate blood–brain barrier tight-junction expression via systemic cytokine and vagus-mediated signaling.
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Butyrate
Gut microbiota ferment indigestible fibers into butyrate, which fuels colonocytes, strengthens tight junctions, and attenuates mucosal inflammation.
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Intestinal permeability
Intestinal permeability is a functional property of the gut epithelium governed by tight-junction dynamics and mucosal signaling.
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Lactobacillus reuteri
In the gut, Lactobacillus reuteri adheres to intestinal epithelium, produces reuterin, and modulates immune signaling to stabilize microbiota.
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Polyphenols
Polyphenols modulate gut microbiota composition and activity, while microbes biotransform polyphenols into bioactive metabolites affecting host physiology.
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Toll-like receptors
Gut epithelial and lamina propria immune cells express Toll-like receptors that sense microbial patterns and initiate NF-κB–mediated innate immunity.
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Vitamin D
Vitamin D, through gut epithelial VDR activation, strengthens mucosal tight junctions, induces antimicrobial peptides, and shapes microbiome composition.
News & Publications
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Nanoplastics are emerging as a new concern in environmental and human health due to their capacity to interact with biological systems at the cellular level. Their small size allows them to penetrate tissues and potentially disrupt key physiological processes, particularly in the gut. A recent study in mice found that polystyrene nanoplastics can disrupt gut bacteria, weaken the intestinal barrier, and trigger molecular changes that may have far-reaching effects on health.
Researchers exposed mice to oral doses of polystyrene nanoplastics four times a week for 12 weeks and used fluorescent labels to track where the particles went. Then, they examined the animals' gut tissue, analyzed changes in their gut microbiota, and evaluated changes in extracellular vesicles—tiny membrane-bound structures released by gut cells and bacteria that facilitate intercellular communication.
The researchers found that nanoplastics accumulated in the gut, liver, and other tissues for up to 48 hours. Mice exposed to nanoplastics gained more weight than unexposed mice—about 28% more—despite no differences in liver or fat tissue mass. Nanoplastic exposure altered gut microbial populations, disrupted mucus production, and interfered with proteins maintaining the gut barrier.
These findings suggest that nanoplastics weaken the gut’s defenses by altering the microbiome and changing how gut cells communicate through extracellular vesicles. Over time, this disruption could increase vulnerability to disease, even without obvious inflammation or liver damage. Learn more about micro- and nanoplastics in our overview article.
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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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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
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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The gut-brain axis may hold more clues about cognitive decline than previously realized, with some evidence suggesting that gut microbial populations might influence brain health and cognitive function. A recent study found that older adults with cognitive impairment had distinct differences in their gut microbes compared to those without impairment.
Researchers assigned 229 adults aged 60 and older to one of two groups based on their cognitive function. They analyzed the diversity and composition of the participants' gut microbes and used machine learning to identify key bacterial species associated with cognitive impairment. They also investigated how lifestyle factors such as diet and exercise influenced these bacterial populations.
They found that participants with cognitive impairment had less diverse gut microbial populations than those without, indicating a potential link between less microbial diversity and cognitive decline. They noted that higher numbers of specific bacteria, including Megamonas, Blautia, and Veillonella, were associated with better cognitive function. They also found that higher fruit intake and regular exercise were linked to increased abundance of these beneficial species.
These findings suggest that maintaining a healthy gut microbiota through diet and exercise is essential in preserving cognitive function as we age. Time-restricted eating helps promote gut microbial diversity. Learn more in this clip featuring Dr. Satchin Panda.
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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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Microplastics absorbed in the gut may promote cancer cell migration and metastasis. www.sciencedirect.com
Plastic pollution is a growing environmental concern, with tiny plastic particles infiltrating various ecosystems, including the human body. The gut is crucial in this process, serving as the main gateway for microplastics and nanoplastics to enter the body. A recent study found that human colorectal cancer cells can absorb microplastic particles, raising concerns about their potential effects on health.
Researchers exposed four human colorectal cancer cell lines to polystyrene micro- and nanoplastics of various sizes (0.25, 1, and 10 micrometers) and concentrations. They tracked the particles' uptake into cells and monitored their behavior during cell division.
They found that all the cancer cells absorbed micro- and nanoplastics, with the highest uptake observed in HCT116 cells—a type of cells commonly used to study various aspects of tumor biology. Notably, the cells didn’t eliminate the absorbed particles. Instead, they passed them on during cell division, sharing them between the original and new cells. Even short-term exposure to the smallest particles (0.25 micrometers) increased the cells' movement, which could facilitate metastasis.
These findings suggest that micro- and nanoplastics accumulate in cells and pass into progeny cells during cell division. Once inside the cells, they promote cell migration, potentially enhancing the spread of cancer. Some harmful effects of microplastics may be due to compounds commonly used in plastic manufacturing, such as bisphenol A, phthalates, and heavy metals. Learn more about microplastics in our overview article.
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Infrequent bowel movements may increase the risk of kidney dysfunction. www.sciencedaily.com
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
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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Inflammatory bowel disease (IBD) is an umbrella term for chronic inflammatory conditions that affect the gut, primarily Crohn’s disease and ulcerative colitis. A growing body of evidence suggests that microplastics – tiny plastic particles ranging between 5 millimeters and 100 nanometers – are pro-inflammatory, potentially contributing to chronic disease. A recent study found that people with inflammatory bowel disease had roughly 49 percent more microplastics in their feces than healthy people.
Researchers measured microplastic concentrations in the feces of 102 participants. Half of the participants had IBD, and the other half were healthy. Participants completed questionnaires about their plastic usage and exposure.
The researchers found that the fecal concentration of microplastic particles in the feces of participants with inflammatory bowel diseases averaged 41.8 particles per gram of dry matter. In comparison, healthy participants' concentrations averaged 28.0 particles per gram. The various particles were in sheets, fibers, fragments, and pellets; most were smaller than 300 micrometers. Participants with higher fecal concentrations tended to have more severe IBD. The primary sources of microplastic exposure were plastic packaging (for food and water) and dust.
These findings suggest that microplastic exposure is linked to the disease process of IBD or that IBD might exacerbate microplastic retention in the body. They also add to the growing evidence suggesting that microplastics influence human health. Scientists have found microplastics throughout the human body, including the sputum, lungs, heart, liver, blood, endometrium, testis, amniotic fluid, and placenta00153-1/fulltext).
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Probiotic improves cognition and normalizes circadian rhythms in sleep-deprived mice. www.sciencedirect.com
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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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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Irritable bowel syndrome (IBS) is a digestive disorder characterized by abdominal cramping, gas, diarrhea, and constipation. The condition affects as many as 10 percent of people worldwide and has no cure. A recent study shows that adopting three or more healthy lifestyle behaviors may reduce the risk of IBS by as much as 42 percent.
The study involved more than 64,000 people enrolled in the UK Biobank database. Researchers collected information about the participants' dietary intake and whether they engaged in any of five healthy lifestyle behaviors: never smoking, getting optimal sleep, engaging in vigorous physical activity, eating a quality diet, and moderating their alcohol intake.
They found that 11.8 percent of the participants did not practice any of the five critical healthy behaviors; 32.1 percent practiced one, 34.1 percent practiced two, and 21.9 percent practiced three to five healthy behaviors. As participants engaged in more healthy behaviors, their likelihood of developing IBS decreased, with those practicing one healthy behavior having a 21 percent lower risk, those with two healthy behaviors having a 36 percent lower risk, and those engaging in three to five healthy behaviors having a 42 percent lower risk. These findings were consistent across various groups, regardless of age, sex, job status, where they lived, history of gastrointestinal infection, endometriosis, family history of IBS, or other lifestyle habits.
These findings suggest that adopting multiple healthy lifestyle behaviors, such as not smoking, staying physically active, and getting good sleep, can significantly reduce the risk of developing IBS. Learn more about factors that influence gut health in this episode featuring Dr. Eran Elinav.
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Vitamin B12 supports metabolic processes involved in stem cell reprogramming and tissue repair. www.irbbarcelona.org
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 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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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
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
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 immune system, recognized for its role in depression, now understood to shape allergen avoidance behavior. www.sciencedaily.com
The immune system plays a critical role in protecting human health. However, a recent study in mice shows that the immune system may influence behavior, too. Mice exposed to allergens – substances that trigger allergies – avoided those substances.
Researchers studied two groups of mice: one that was predisposed to egg allergy and one that was not. They exposed the two groups to water that contained ovalbumin, a protein in eggs that triggers allergic reactions.
They found that regions of the predisposed animals' brains that respond to unpleasant stimuli became active when they ingested allergens, causing them to avoid the ovalbumin-containing water. The mechanisms driving this behavior involved activation of IgE antibodies and mast cells (essential immune system components), which, in turn, triggered the activity of key immune-related molecules – cysteinyl leukotrienes and growth and differentiation factor-15 (GDF-15). Interestingly, the animals' avoidance behavior occurred before allergy-associated gut inflammation manifested.
Cysteinyl leukotrienes are pro-inflammatory lipid mediators produced by various immune cells, including mast cells, eosinophils, basophils, and macrophages. GDF-15 is a cytokine that increases in response to stress, infection, and inflammation. It increases in aging, suppressing immune responses.
These findings suggest that the immune system can shape behavior in response to allergens in mice, potentially protecting against harmful exposures. The immune system also influences behavior by inducing depressive symptoms during periods of acute or, alternatively, chronic inflammation. Learn more in this clip featuring Dr. Charles Raison.
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Sleep deprivation leads to fatal accumulation of oxidative stress in the gut, but antioxidant diet can extend lifespan. www.genengnews.com
Sleep – a state that renders animals stationary and less responsive to stimuli – is crucial for survival. Some evidence suggests that sleep is important because it protects the body against harmful oxidative stress. A 2020 study in flies and mice showed that reactive oxygen species, which drive oxidative stress, accumulate in the gut during sleep deprivation, leading to death.
Researchers deprived flies and mice of sleep for various durations, occasionally allowing them to sleep. Then, they measured reactive oxygen species in the animals' tissues, including the heart, brain, muscles, and gut. They repeated the experiment but gave the animals antioxidant compounds during the sleep deprivation period.
They found that animals that experienced extended sleep deprivation died, but allowing them to sleep periodically prevented death, albeit with slightly shorter lifespans. Sleep deprivation markedly increased reactive oxygen species in the animals' guts. After ending the sleep deprivation, the reactive oxygen species levels slowly decreased, nearly returning to their baseline levels. Providing the animals with dietary antioxidant compounds reduced the harmful effects of reactive oxygen species, and the animals lived normal lifespans despite sleep deprivation.
These findings suggest that sleep deprivation shortens lifespan and causes death due to the accumulation of reactive species in the guts of flies and mice. However, dietary antioxidant compounds reduce reactive oxygen species in the gut and moderate the harmful effects of sleep deprivation. Learn how sleep deprivation affects the brain in this short video featuring Dr. Rhonda Patrick.
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Eating broccoli may safeguard the gut by increasing the number of goblet and Paneth cells. www.sciencedaily.com
The list of health attributes of broccoli includes anticancer, antioxidant, and anti-diabetes effects, as well as many others. Now a new study in mice shows that eating broccoli protects the gut. Molecules in broccoli interact with proteins present in the small intestine, increasing the number of cells involved in safeguarding the gut.
Researchers fed one group of mice a diet containing 15 percent freeze-dried broccoli – roughly equivalent to 3.5 cups of fresh broccoli in the human diet. They fed another group their typical food, which included no broccoli. Then they examined the animals' small intestines to assess the effects of broccoli consumption on the gut.
They found that molecules in the broccoli – likely phytochemicals, microbiota, or byproducts of metabolism – bound with specific proteins in the gut called aryl hydrocarbon receptors. Subsequently, the number of goblet and Paneth cells in the animals' guts increased. Goblet cells produce mucus, which protects and lubricates the gut to facilitate the passage of food. Paneth cells produce antimicrobial peptides and immune factors that regulate the gut microbial composition.
These findings suggest that broccoli consumption protects the gut via interaction with the aryl hydrocarbon receptor. Broccoli is a rich source of phytochemicals, including sulforaphane, an isothiocyanate compound with potent antioxidant, anticancer, and anti-inflammatory properties. Learn more about sulforaphane in this episode featuring Dr. Jed Fahey.
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Gut bacteria implicated in Parkinson's disease pathophysiology. medicalxpress.com
Aggregates of alpha-synuclein – a protein present in the human brain – are a hallmark of Parkinson’s disease. But what triggers the protein’s aggregation has long remained a mystery. New research suggests that bacteria in the gut drive alpha-synuclein aggregation, contributing to the pathophysiology of Parkinson’s disease.
Researchers isolated a type of bacteria called Desulfovibrio from fecal samples taken from 10 people with Parkinson’s disease and their healthy spouses. Then they fed the bacteria to a type of worm often used to study Parkinson’s disease.
They found that worms fed Desulfovibrio bacteria from people with Parkinson’s disease had more and larger alpha-synuclein aggregates than those fed Desulfovibrio bacteria from healthy people. The Desulfovibrio-fed worms were also more likely to die prematurely.
These findings suggest that Desulfovibrio bacteria contribute to the pathophysiology of Parkinson’s disease. Learn more about Parkinson’s disease in this episode featuring Dr. Giselle Petzinger.
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Melatonin, commonly used to improve sleep, may aggravate bowel inflammation by increasing TNF-alpha in acute colitis medicalxpress.com
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
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 barrier dysfunction impairs butyric acid uptake into the blood – potentially increasing the risk of carotid atherosclerosis. www.nature.com
Poor gut barrier function may contribute to carotid atherosclerosis – a narrowing of the blood vessels that supply the brain – according to a new study. People with carotid atherosclerosis demonstrated increased markers of gut barrier damage and inflammation, both of which impair butyric acid uptake into the blood.
Researchers conducted a study involving 43 people with carotid atherosclerosis and 44 healthy people. They measured butyric acid levels in the participants' blood and feces and assessed their gut health and inflammation.
The people who had carotid atherosclerosis had higher levels of butyric acid in their feces but not in their blood, despite robust gut microbial production of butyric acid. They also had higher levels of markers that indicate gut barrier damage and inflammation and tended to be heavier, carry more weight around their waist, have poor blood glucose control, and have higher markers of inflammation.
The researchers hypothesized that the participants' higher fecal (but not blood) levels of butyric acid were due to poor gut barrier function, which could impair butyric acid absorption and in turn reduce its uptake into the blood. Other research has found that high fecal levels of butyric acid are associated with intestinal permeability, obesity, metabolic dysfunction, and high blood pressure.
Butyric acid, a short-chain fatty acid, is best known for its roles in maintaining gut barrier function and preventing intestinal permeability. However, butyric acid also protects the vascular endothelium – the lining of the blood vessels. Having low butyric acid levels in the blood could contribute to the risk of developing carotid atherosclerosis.
[Learn about butyrate, a compound related to butyric acid, in our overview article.] (https://www.foundmyfitness.com/topics/butyrate)
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Red food dye promotes inflammation in the gut, altering the gut microbiota. www.sciencedaily.com
Exposure to a dye found in many commonly consumed foods may increase the risk of developing inflammatory bowel diseases, a new study finds. The dye impairs gut barrier function and increases serotonin production, altering the gut microbiota.
Researchers fed mice either normal mouse chow or mouse chow that contained a red food dye called Allura Red for 12 weeks and assessed their gut health. Allura Red, also known as FD&C Red 40 or Food Red 17, is used in many food products, including candy, soft drinks, dairy products, and some breakfast cereals.
The researchers found that exposure to the dye when the mice were young heightened the animals' susceptibility to colitis (a type of inflammatory bowel disease) later in life. Mice that developed colitis had higher gut serotonin levels and impaired gut barrier function.
Elevated gut serotonin promotes gut inflammation and is a common feature of inflammatory bowel diseases. Impaired gut barrier function drives intestinal permeability (also known as “leaky gut”) – a condition in which gaps form between the cells that line the gut. Intestinal permeability allows pathogens to leak through the intestinal barrier and pass directly into the bloodstream, promoting inflammation.
The findings from this study suggest that exposure to a commonly used food additive increases the risk of developing inflammatory bowel disease by promoting intestinal permeability. Read more about intestinal permeability in our overview article.
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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
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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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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Butyrate, a short-chain fatty acid produced in the gut, reduces skin allergies.
The skin is an important biological barrier that plays critical roles in the body’s innate immune response. Skin allergies, which typically appear early in life and can impair barrier function, have become more common in recent decades. Findings from a recent study suggest that butyrate, a short-chain fatty acid produced in the gut, reduces atopic dermatitis, a type of skin allergy.
Short-chain fatty acids are fatty acids that contain fewer than six carbons in their chemical structure. They are produced by the gut microbiota during the fermentation of dietary fiber and are crucial to gut health. Short-chain fatty acids may play roles in the prevention and treatment of metabolic syndrome, inflammatory bowel disorders, and certain types of cancer. Some evidence suggests they can cross the blood-brain barrier to affect brain function. The principal short-chain fatty acids produced in the human gut are acetate, propionate, and butyrate.
The investigators first exposed two groups of mice to an allergen that induces a skin condition similar to atopic dermatitis. They fed both groups a low-fiber diet, but they supplemented one group with inulin, a type of fiber that undergoes microbial fermentation in the gut to produce butyrate. They supplemented the other group with cellulose, which does not readily ferment. They found that compared to the cellulose-supplemented mice, the mice that ate the inulin-supplemented diet had less severe skin disease, better barrier function, and a milder immune response, which they attributed to butyrate.
Next, they tracked the movement of butyrate in the animals' bodies and determined that it traveled quickly from the gut to the skin (about 45 minutes), where it directly influenced the mitochondrial metabolism of keratinocytes, the dominant cell type in the epidermal layer of the skin. Finally, they analyzed gene expression in skin collected from both groups of mice and observed a twofold increase in gene expression related to immunity and barrier function in the butyrate-exposed mice.
These findings suggest that butyrate influences skin health and reduces skin allergies. Learn more about the beneficial health effects of 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
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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TLR4 receptor involved in recognizing and triggering the innate immune system in response to bacteria may be involved in reinforcing binge drinking www.sciencedaily.com
Genetic activation of TLR4 in the brain reduced binge drinking. What makes this so interesting is that alcohol consumption itself promotes intestinal permeability, which increases systemic activation of TLR4, potentially resulting in negative cardiovascular outcomes, among other things.
From the article:
One of the study’s most novel findings concerns TLR4’s important role in binge drinking. Science has traditionally considered TLR4 to be an innate immunity receptor involved with neuroinflammation in the brain. Scientists associated TLR4 with microglia, cells that support inflammatory responses in the brain. “What makes this finding particularly important for the field of neuroscience is that we’re showing that TLR4 plays a significant role in neurons, specifically, the neurons that are connected to the GABA receptor,” says Dr. June.
To establish the connection between the GABA receptors, TLR4 and alcohol, the scientists manipulated this pathway in the binge drinking rodents. Dr. Aurelian was a pioneer in developing a method to inhibit gene expression, helping scientists to pinpoint the role of individual genes in the body. […] The scientists found that when they artificially stimulated the GABA receptors and TLR4 in order to simulate the good feelings binge drinkers feel when drinking alcohol, the rats lost interest in alcohol for two weeks after the procedure.
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Salt may increase blood pressure partly through reducing the production of ketone beta-hydroxybutyrate www.sciencedaily.com
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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Sugar may drive inflammatory bowel disease through the promotion of mucin-consuming microbes. www.science.org
Inflammatory bowel disease (IBD) is an umbrella term for two chronic inflammatory conditions that affect the digestive tract – ulcerative colitis and Crohn’s disease. Symptoms of IBD include diarrhea, rectal bleeding, abdominal pain, fatigue, and weight loss. Evidence indicates that dysbiosis, an imbalance in the types and numbers of microbes in the gut, contributes to the pathogenesis of IBD. And now, findings from a recent study suggest that eating a high-sugar diet promotes dysbiosis and the development of IBD.
The study involved normal mice and mice that are genetically predisposed to develop colitis. The authors of the study gave a subset of both groups of mice a 10 percent glucose solution (comparable to a sugar-sweetened soft drink) for one week. They gave the normal mice a chemical that causes colitis. Then they measured the inflammatory responses, disease severity, and gut microbial composition in both groups of mice and compared them to mice that did not receive the sugar solution.
They found that, prior to the mice developing colitis, the sugar did not trigger gut inflammation. However, both groups of mice developed worse symptoms of colitis after drinking the glucose solution. In addition, both groups exhibited higher numbers of bacteria that break down the mucus layer of the gut (specifically, Akkermansia muciniphila and Bacteroides fragilis), contributing to mucus layer destruction, increasing gut permeability. The number of beneficial bacteria in the animals' guts decreased, however.
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Turmeric curcumin reduces inflammation in the gut in response to gluten. pubmed.ncbi.nlm.nih.gov
“Wheat is a major diet from many years; apart from its nutritious value, the wheat protein gliadin is responsible for many inflammatory diseases like celiac disease (CD), and non-celiac gluten sensitivity (NCGS).”
“Cells were cultured and exposed to 160 μg/ml of gliadin, 100 μM H2O2, and 10 μM curcumin (3 h pretreatment) followed by the assessment of inflammation.
“The results show that gliadin increases the advanced oxidation protein products level and the activity of myeloperoxidase and NADPH oxidase expression. It enhances inflammation by increasing expression of pro-inflammatory cytokines, altered expression of anti-inflammatory, and regulatory cytokines. It exacerbates the cellular damage by increasing MMP-2 and 9 and decreasing integrin α and β expression. Gliadin promotes disease pathogenesis by inducing the inflammation and cellular damage which further alter the cellular homeostasis. The pretreatment of curcumin counteracts the adverse effect of gliadin and protect the cells via diminishing the inflammation and help the cell to regain the cellular morphology suggesting phytochemical-based remedial interventions against wheat allergies.”
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Specialized cells in the gut differentiate between sugar and artificial sweeteners. www.eurekalert.org
The ability to detect sweetness – whether from sugar or artificial sweeteners – relies on the activity of specialized proteins in the mouth and nasal passages called taste receptors. However, researchers have found that mice that don’t have taste receptors can tell the difference between sugar and artificial sweeteners – and prefer sugar. Findings from a recent study suggest that the capacity to differentiate between sugar and artificial sweeteners is due to the activity of unique cells call neuropods.
Neuropods are enteroendocrine cells – specialized cells that line the gut and sense the presence of food. Located primarily in the duodenum (the upper portion of the intestine), neuropods form synapses (neural connections) with the vagus nerve, a cranial nerve that regulates multiple aspects of the body’s internal functions, including those in the gut. The presence of sugar in the gut causes neuropods to release glutamate, a type of neurotransmitter, facilitating communication via the gut and brain.
The researchers first determined whether neuropods' response to sweetness is specific to sugar, using organoids derived from the intestinal tissues of mice and humans. Organoids are three-dimensional tissue cultures produced from stem cells. They mimic the structure and activity of the organ from which they are derived. The researchers exposed the organoids to sugar or sucralose (an artificial sweetener) and found that sugar promoted the release of glutamate, but sucralose did not.
Then they determined whether the preference for sugar (over artificial sweeteners) arises in the brain or the gut using optogenetics. Optogenetics is a research technique that allows scientists to switch a neuron’s activity on or off using light and genetic engineering. When they turned the neuropod cells in the gut of a living mouse on or off, they found that when the neuropod cells were off, the mouse no longer showed a clear preference for sugar.
These findings suggest that neuropod cells in the gut drive responses to and preferences for sugar. They may further explain why artificial sweeteners often don’t curb the desire (or craving) for sugar. Sugar is ubiquitous in the Western diet and is especially abundant in sugar-sweetened beverages. Learn about the health effects of consuming sugar-sweetened beverages in our overview article.
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Social support is a necessary resource for maintaining physical and mental health. Conversely, loneliness is associated with depression, poor sleep, impaired cognitive function, and early death. Findings of a new study show a relationship between the gut microbiota and feelings of wisdom, compassion, and social support.
The gut microbiota is composed of bacteria and other microorganisms that are unique to each individual. A microbiota with high alpha-diversity, meaning a greater number of microbial species, supports health and reduces the risk of diseases such as inflammatory bowel disease and liver disease. Scientists don’t fully understand how gut microbiota diversity relates to social support.
The investigators analyzed data from 184 participants between the ages of 21 and 100 years who were taking part in a larger study about aging. Participants completed a phone interview during which they answered questions about their social habits, health, and wellbeing. They also provided a fecal sample for sequencing of bacterial DNA in their gut microbiota.
The data revealed a significant statistical relationship among alpha-diversity and loneliness, wisdom, social support, compassion, and social engagement. Individuals with low alpha-diversity reported higher levels of loneliness and lower levels of all positive social variables. These relationships remained significant even when taking age and body mass index (a proxy for body fat) into account. The researchers found no relationship between alpha-diversity and sex, physical health, or depression.
These results are the first to show an association between low alpha-diversity and loneliness. Although the researchers found no association between low alpha-diversity and poor mental and physical health in this study, future studies are needed to explore this relationship further. This research is especially important given that loneliness has sharply increased during the COVID-19 pandemic.
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Polyphenols prevent leaky gut syndrome. www.eurekalert.org
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
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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Fermented foods decrease inflammation and increase diversity of the gut microbiota. www.sciencedaily.com
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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Wearable device may predict inflammatory bowel disease flare-ups. www.sciencedaily.com
Inflammatory bowel diseases, a group of conditions characterized by chronic inflammation of the digestive tract, affect the lives of nearly seven million people worldwide. The two most common inflammatory bowel diseases are ulcerative colitis and Crohn’s disease. A report published in 2020 describes a wearable device that detects the presence of biomarkers associated with inflammatory bowel diseases in sweat, potentially signaling a symptom flare.
A common feature of many inflammatory bowel diseases are periods of remission and relapse, often referred to as “flares.” During flares, interleukin-1 beta (IL-1 beta) and C-reactive protein (CRP), are often elevated. IL-1 beta is a proinflammatory cytokine that mediates the body’s inflammatory response. CRP is a protein that increases in the blood with inflammation and infection.
The authors of the study developed a wearable, watch-like device that monitored levels of IL-1 beta and CRP in the sweat of 20 healthy adults (18 to 65 years old) over a period of up to 30 hours. They studied healthy people to help establish the levels of these two biomarkers in people without inflammatory bowel disease. A removable strip on the device collected the sweat, providing real-time monitoring of the biomarkers. They also measured the biomarkers using a standard assay and compared the two assessments.
They found that the device was highly accurate at measuring sweat levels of IL-1 beta and CRP, compared to measurements with the standard assay. Their findings demonstrate proof-of-feasibility for a wearable device that can signal an inflammatory bowel disease flare. Use of such a device may offer a non-invasive way to help people with inflammatory bowel disease track their inflammatory status and help guide clinicians' treatment decisions.
The authors of this study later measured pro-inflammatory proteins in the sweat of people with COVID-19 to predict cytokine storm, a potentially life-threatening condition that occurs when an infection provokes an excessive immune response. They found that their sweat-based sensor detected cytokine levels in passive sweat that correlated with cytokine levels in the patients' blood.
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Leaky gut decreases the beneficial effects of dietary polyphenol compounds in older adults. pubs.acs.org
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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Compounds in e-cigarettes trigger inflammation, promoting a leaky gut. ucsdnews.ucsd.edu
In recent years, vaping, or smoking electronic cigarettes (e-cigarettes), has emerged as a popular substitute for smoking tobacco-containing cigarettes. E-cigarettes produce a vapor that may contain nicotine as well as a variety of toxic substances, including some carcinogens. Findings from a new study suggest that some compounds in e-cigarettes trigger inflammation, promoting a leaky gut.
Leaky gut, otherwise known as intestinal permeability, is a condition in which gaps form between the tight junctions between the endothelial cells that line the gut. These gaps allow pathogens like bacteria or endotoxins (toxins that are released when bacteria die) to leak through the intestinal wall and pass directly into the bloodstream. Leaky gut has been linked with a number of chronic diseases, including Alzheimer’s disease and cardiovascular disease.
The authors of the study exposed mice to e-cigarette vapors for one hour per day and then they examined the animals' colons at one week and three months after the chronic exposure. Then they measured gene expression in the colons. They also built gut enteroids – three-dimensional tissue models that incorporate many of the features of human gut tissue, including an epithelial layer surrounding a functional lumen and all of the cell types normally found in the gut. They exposed the enteroids to e-cigarette vapor (with or without nicotine).
They found that exposure to e-cigarette vapor promoted leaky gut, increasing the susceptibility of the gut lining to bacterial infections, and triggering gut inflammation. Use of the two models established that the primary components in the vapor responsible for the harmful effects were propylene glycol and vegetable glycerol, compounds present in more than 99 percent of all e-cigarettes. They also found that e-cigarette vapor altered expression of genes involved in the cellular response to stress, infection, and inflammation.
These findings demonstrate that commonly used substances present in e-cigarettes promote leaky gut and drive inflammation and provide insights into the long-term health effects of e-cigarettes. They also underscore public health efforts to reduce e-cigarette use.
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Simple sugars alter gut microbiota and induce colitis in mice. www.sciencedaily.com
Colitis is an inflammatory bowel disease characterized by inflammation of the colon, accompanied by diarrhea and weight loss. It is caused by a combination of genetic and environmental factors and is more common among people who adhere to a Western dietary pattern high in simple sugars. New research demonstrates how consumption of simple sugars may alter the composition of the gut microbiota in a way that promotes inflammation and disease.
Akkermansia muciniphila (A. muciniphila) is a bacterial species commonly found in the human gut. It degrades mucin, a type of gelatinous protein produced by the intestines to maintain a barrier between the cells that line the gut and the gut microbiota. People with obesity and metabolic disease often have less A. muciniphila in their guts, leading many to explore this species as a probiotic for a number of conditions. However, dietary imbalances can cause A. muciniphila to damage the gut barrier integrity and induce inflammation.
The authors of the study first used a model of colitis that mimics environmental exposure to toxins and then replicated these results in a second model of colitis that mimics genetic susceptibility to colitis. They fed mice a diet providing 10 percent glucose by weight (similar to the sugar content of sugar-sweetened soda) or a normal diet for one week prior to the development of colitis. Mice on the high glucose diet exhibited worse colitis severity, including more diarrhea and weight loss. Mice who continued to consume a high glucose diet after developing colitis continued to experience more severe symptoms.
Through a number of intricate experiments, the authors determined that a high sugar diet increased the number of mucin-degrading bacteria such as A. muciniphila and Bacteroides fragilis. When given antibiotics (which destroy gut bacteria, including mucin-degrading species), glucose-treated mice exhibited less inflammation and less severe colitis symptoms. Finally, when genetically susceptible mice were given a fecal microbiota transplant from glucose-fed healthy mice, they developed more severe colitis, demonstrating the ability to transmit risk from one mouse to another.
This study provides new information about the effects of dietary sugars on colitis severity. The authors provided a wealth of data from a series of well-controlled experiments in mice; however, they noted that the microbiota of mice and humans are very different and clinical studies are needed to confirm these results.
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Gut microbial conversion of glucosinolates to isothiocyanates is highly variable in humans. cancerpreventionresearch.aacrjournals.org
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.
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Consumption of probiotics and prebiotics has beneficial effects on the gut-brain axis and mental health. www.sciencedaily.com
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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Human milk oligosaccharide supplementation improves gut microbial profile in people with irritable bowel syndrome. pubmed.ncbi.nlm.nih.gov
Irritable bowel syndrome (IBS), an intestinal disorder characterized by abdominal pain, bloating, and alternating episodes of diarrhea and constipation, affects as many as 14 percent of people living in the United States. Evidence suggests that people with IBS often have dysbiosis, an imbalance in the microbial makeup of the gut. A recent study indicates that human milk oligosaccharides may be beneficial in modulating the gut microbial profile of people who have IBS.
Human milk oligosaccharides (HMOs) are complex, indigestible sugars in breast milk. They serve as prebiotics – compounds that induce the growth or activity of beneficial bacteria – in the infant gut. Evidence indicates they also act as “decoys” to protect the infant from gut infections; break down biofilms that group-B streptococcus bacteria create to protect themselves from antimicrobials and antibiotics; and enhance the activity of some antibiotics by increasing the membrane permeability of pathogenic bacteria.
The phase 2, parallel, double-blind, randomized, placebo-controlled trial involved 61 adult men and women with IBS. The authors of the study assigned each participant to one of three groups, consuming a 5-gram or a 10-gram dose of an HMO product or a placebo for four weeks with a four-week follow-up period after the end of the intervention. They scored the participants' IBS symptoms using standardized symptom rating scales and assessed their overall fecal microbial composition using genome-based microbiota profiling.
None of the participants reported significant changes in their symptoms at week four or eight. However, the participants who took the 10-gram dose had higher quantities of fecal bifidobacteria at week four, but not at week eight, compared to the other groups. Higher levels of bifidobacteria are associated with health and longevity in older adults, but lower levels of bifidobacteria are associated with several chronic diseases, including IBS, inflammatory bowel diseases, and metabolic disorders.
These findings demonstrate that HMOs might be beneficial in restoring the gut microbiota of IBS patients toward a healthier profile.
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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 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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A gut-brain axis specific to glucose drives sugar preference, potentially explaining sugar cravings. www.sciencedaily.com
Sugar provides necessary energy in the human diet, but excess sugar consumption is associated with weight gain and metabolic disorders. The average person living in the United States consumes approximately 100 pounds of sugar per year. Findings from a recent study suggest that our preference for sugar has its origins in the brain.
The authors of the study gave mice water that was sweetened with either sugar or acesulfame, an artificial sweetener commonly used in diet drinks and foods. At first, the mice chose to drink both solutions, but after two days, the mice chose the sugar-sweetened water only.
The researchers analyzed the brain activity of the mice when they drank the two solutions and found that a particular region of the brain responds to sugar – an area called the caudal nucleus of the solitary tract, which is located in the brain stem. They discovered that signals originating in the gut travel along the vagus nerve to this region of the brain to create a gut-brain-axis specific to glucose and similar molecules. Intake of these molecules stimulates even greater consumption, setting up an environment conducive to overconsumption.
Identification of this neural pathway provides insights into human consumption of sugar and might inform the development of new strategies to reduce intake.
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Gut bacteria may alter the aging process of the human brain through the production of butyrate www.sciencedaily.com
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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Sugar binges increase risk of inflammatory bowel disease. www.sciencedaily.com
Approximately 3 million people living in the United States have inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis. The Western diet – a dietary pattern that is high in unhealthy fats and refined sugar, and low in fiber – has been implicated in the pathogenesis of IBD. A new study suggests that even short-term exposure to a high sugar diet increases susceptibility to ulcerative colitis.
The study involved mice that were fed either regular mouse chow or a diet that was high in sugar (approximately 50 percent sucrose). After two days, the mice were treated with dextran sodium sulfate, a chemical that induces colitis. The mice were then assessed for changes in the diversity of their gut microbiota, disease severity, gut permeability, and short-chain fatty acid (SCFA) concentrations. Increased gut permeability (also known as “leaky gut”) – a condition in which gaps form between the tight junctions of the endothelial cells that line the gut – allows pathogens to leak through the intestinal wall and pass directly into the bloodstream, promoting inflammation. Short-chain fatty acids are products of microbial fermentation that dampen inflammation in the gut.
The mice that ate the high sugar diet exhibited decreased diversity among their gut microbiota, increased gut permeability, and lower concentrations of SCFAs. They were much more likely to develop colitis than the mice that ate the regular chow. These findings suggest that even short-term exposure to a high sugar diet can influence susceptibility to IBD.
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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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More Evidence for Gut-Brain Link in Alzheimer's Disease www.medscape.com
“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."
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Role of dietary transition metals on host microbiota and risk of disease www.gutmicrobiotaforhealth.com
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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Food Additives Causing Harm, Reforms Urgently Needed, AAP Says www.medscape.com
The Worst Offenders:
The statement addresses 2 broad categories of additives: direct and indirect. Indirect additives refers to substances in “food contact materials,” such as “adhesives, dyes, coatings, paper, paperboard, plastic, and other polymers,” the authors of the policy statement explain. Direct food additives include chemicals such as colorings, flavorings, and preservatives added to food during processing. Within those two categories the authors identified six types of additives of most concern, based on accumulating evidence summarized in the report and in an accompanying press release:
Bisphenols: Used to manufacture plastic containers and food and beverage cans, these compounds have been associated with endocrine and neurodevelopmental disruption and obesogenic activity, with alterations in the timing of puberty, reduced fertility, and impaired neurological and immunological development. One bisphenol, bisphenol A, has already been banned from baby bottles and sippy cups. Phthalates: As components of plastic wrap and plastic tubing and containers, phthalates similarly have been implicated in endocrine disruption and obesogenic activity. "A robust literature" shows that these chemicals adversely affect male sexual development, may contribute to childhood obesity and insulin resistance, and may also contribute to cardiovascular disease. Perfluoroalkyl chemicals: These chemicals are used in the manufacture of greaseproof paper and cardboard packaging. They have been associated with immunosuppression, endocrine disruption such as impaired thyroid function, and decreased birth weight. Perchlorate: Often added to plastic packaging for dry foods to control static electricity, perchlorate has been shown to disrupt production of thyroid hormone, with implications for subsequent cognitive function. Of particular concern is exposure among pregnant women, "given that the developing fetus is entirely reliant on the maternal thyroid hormone during the first trimester of pregnancy," the authors write in the technical report. They suggest that perchlorate "may be contributing to the increase in neonatal hypothyroidism and other thyroid system perturbations that have been documented in the United States." Nitrates and nitrites: As direct food additives, these compounds are used as preservatives and color enhancers in cured and processed meats, fish, and cheese. There has been "longstanding concern" over their use, the authors write, because of an association with cancers of the nervous and gastrointestinal systems, and methemoglobinemia in infants. They were classified as "probable human carcinogens" in 2006 by the International Agency for Research on Cancer. Artificial food colors: Often added to products that appeal to children, such as juice drinks, artificial food colors have been associated in some studies with an increased risk for attention-deficit hyperactivity disorder. Although their mechanisms of action are not yet completely understood, and the research "should be interpreted with caution," the authors recommend "a thorough reassessment" of artificial food colors to ensure they are safe. -
Exercise training-induced modification of the gut microbiota persists ..... www.tandfonline.com
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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Probiotic Bifidobacterium strains and galactooligosaccharides improve intestinal barrier function in obese adults microbiomejournal.biomedcentral.com
Full Title: Probiotic Bifidobacterium strains and galactooligosaccharides improve intestinal barrier function in obese adults but show no synergism when used together as synbiotics
Background: One way to improve both the ecological performance and functionality of probiotic bacteria is by combining them with a prebiotic in the form of a synbiotic. However, the degree to which such synbiotic formulations improve probiotic strain functionality in humans has not been tested systematically. Our goal was to use a randomized, double-blind, placebo-controlled, parallel-arm clinical trial in obese humans to compare the ecological and physiological impact of the prebiotic galactooligosaccharides (GOS) and the probiotic strains Bifidobacterium adolescentis IVS-1 (autochthonous and selected via in vivo selection) and Bifidobacterium lactis BB-12 (commercial probiotic allochthonous to the human gut) when used on their own or as synbiotic combinations. After 3 weeks of consumption, strain-specific quantitative real-time PCR and 16S rRNA gene sequencing were performed on fecal samples to assess changes in the microbiota. Intestinal permeability was determined by measuring sugar recovery in urine by GC after consumption of a sugar mixture. Serum-based endotoxin exposure was also assessed.
Results: IVS-1 reached significantly higher cell numbers in fecal samples than BB-12 (P < 0.01) and, remarkably, its administration induced an increase in total bifidobacteria that was comparable to that of GOS. Although GOS showed a clear bifidogenic effect on the resident gut microbiota, both probiotic strains showed only a non-significant trend of higher fecal cell numbers when administered with GOS. Post-aspirin sucralose:lactulose ratios were reduced in groups IVS-1 (P = 0.050), IVS-1 + GOS (P = 0.022), and GOS (P = 0.010), while sucralose excretion was reduced with BB-12 (P = 0.002) and GOS (P = 0.020), indicating improvements in colonic permeability but no synergistic effects. No changes in markers of endotoxemia were observed.
Conclusion: This study demonstrated that “autochthony” of the probiotic strain has a larger effect on ecological performance than the provision of a prebiotic substrate, likely due to competitive interactions with members of the resident microbiota. Although the synbiotic combinations tested in this study did not demonstrate functional synergism, our findings clearly showed that the pro- and prebiotic components by themselves improved markers of colonic permeability, providing a rational for their use in pathologies with an underlying leakiness of the gut.
Keywords: Synbiotic, Probiotic, Prebiotic, Obesity, Gut barrier function, Autochthonous, Allochthonous, Galactooligosaccharide, Bifidobacteria, Bifidobacterium
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Gut microbiota resilience as an emerging measure of health - Gut Microbiota for Health www.gutmicrobiotaforhealth.com
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 (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
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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A common antimicrobial agent (called Triclosan) was found to increase the severity of colitis symptoms and promote tumor growth. stm.sciencemag.org
A common antimicrobial agent found in some soaps and toothpaste (called Triclosan) was found to increase the severity of colitis symptoms and promoted colitis-associated colon cancer cell growth (in mice).
Triclosan has also been linked to hormone disruption and drug-resistant bacteria. It has been found in the urine of about three-fourths of doctors and nurses. It is also among the most common chemicals to be detected in streams.
In addition to soaps, it has also been found in dust particles in buildings.
In December 2017, the FDA issued a final rule regarding certain over-the-counter health-care antiseptic products. Companies will not be able to use triclosan or 23 other active ingredients in these products without premarket review due to insufficient data regarding their safety and effectiveness.
Read more here: https://www.fda.gov/ForConsum%E2%80%A6/ConsumerUpdates/ucm205999.htm
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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
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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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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VSL#3 improved HDL, insulin sensitivity, LDL, atherogenic factors, and inflammation www.ncbi.nlm.nih.govGut 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
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
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.comGut 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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Supplemental probiotics for 12 weeks improved cognition in Alzheimer's patients & also lowered inflammatory markers. www.sciencedaily.comBrain 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
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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Why Broth is Beautiful: Essential Roles for Proline, Glycine and Gelatin - Weston A Price www.westonaprice.org
Gelatin’s traditional reputation as a health restorer has hinged primarily on its ability to soothe the GI tract. “Gelatin lines the mucous membrane of the intestinal tract and guards against further injurious action on the part of the ingesta,” wrote Erich Cohn of the Medical Polyclinic of the University of Bonn back in 1905. Cohn recommended gelatin to people with “intestinal catarrh”–an inflammation of the mucus membrane now called irritable bowel syndrome. Interestingly, the type of gelatin used in follow-up experiments done on people with even more serious intestinal diseases was specified as a “concentrated calves foot broth.”37 This form of gelatin would have been rich in cartilage and bone and presumably provide a better amino acid profile than straight collagen. A 1999 German study also proved the truth of the saying “Man ist was man isst.” Their study was inspired by reports of the positive influence of gelatin on degenerative diseases of the musculo-skeletal system and curiosity about the “therapeutic mechanism and the absorption dynamics.” Mice fed radioactive gelatin hydrolysate were compared to control mice administered radioactive proline. They found that 95 percent of the gelatin was absorbed within the first 12 hours, and the labeled gelatin found in the tissues was similar to that of labeled proline with one exception–the absorption and accumulation of gelatin in the cartilage was twice as high. This suggested a salutary effect of gelatin on cartilage metabolism that would not occur with the ingestion of proline alone. They concluded, “These results demonstrate intestinal absorption and cartilage tissue accumulation of gelatin hydrolysate and suggest a potential mechanism for previously observed clinical benefits of orally administed gelatin.”51 - See more at: http://www.westonaprice.org/health-topics/why-broth-is-beautiful-essential-roles-for-proline-glycine-and-gelatin/#sthash.G5l30GLj.dpuf