Brown Fat
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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 Ketosis Heart Disease Omega-3 Fasting Pregnancy Eyes Muscle Sauna Protein Dairy Intestinal Permeability Brown Fat Moringa SupplementsDr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.
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News & Publications
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Chronic cold exposure reduces tumor growth by 80 percent and doubles survival rates in mice. www.newscientist.com
Cancer treatments often target glucose uptake to impede tumor growth, primarily through pharmaceuticals, many of which exert considerable side effects. However, cold exposure is emerging as a potential alternative to these drug-based therapies. A recent study in mice found that cold exposure reduced tumor growth by 80 percent and increased survival rates twofold.
Researchers conducted a two-part study in mice and humans. First, they exposed mice with cancer to cold (4°C, 39°F) or thermoneutral (30°C, 86°F) temperatures for about three weeks. They found that the cold exposure activated the animals' brown fat, depleting the energy supply available to the tumors. The cold-exposed mice exhibited marked tumor growth inhibition and a nearly twofold increase in survival rates relative to the thermoneutral mice. Interestingly, when they fed the cold-exposed mice a high-glucose diet, the animals did not experience the same extent of tumor growth inhibition, suggesting that glucose scarcity was pivotal in suppressing cancer growth.
In the second part of the study, they exposed healthy people to cool temperatures (16°C, 61°F) for two to six hours per day for 14 days and found that the participants experienced brown fat activation similar to the mice. Then, they exposed a person with Hodgkin’s lymphoma to cool (22°C, 71°F) temperatures for seven days and found that the participant exhibited activated brown fat and their tumor showed diminished glucose consumption, suggesting the findings in mice translate to humans.
These findings suggest that cold exposure activates brown fat, reducing blood glucose and impeding tumor growth. Brown fat is a thermogenic (heat-producing) tissue. Studies in animals and humans suggest that brown fat can improve glucose and insulin sensitivity, increase fat oxidation, and protect against diet-induced obesity. Cold exposure increases brown fat volume and metabolism and drives glucose uptake. Learn more about cold exposure and its effects on brown fat in our overview article.
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Maternal omega-3 potentiates fetal brown fat via synergistic action of miRNA production and histone modifications, possibly a lifelong benefit www.sciencedirect.com
Omega-3 supplementation during pregnancy promotes brown fat formation in offspring.
A new study in mice showed that omega-3 fatty acid consumption during pregnancy and lactation promoted the formation of brown fat in offspring. Omega-3s also increased energy expenditure and cold resistance.
Researchers fed female mice either a diet rich in omega-3 fatty acids or a diet devoid of omega-3s throughout their pregnancies and lactation. They measured their offspring’s brown fat and energy expenditure and assessed their capacity to maintain their core body temperature in cold temperatures.
They found that the mice whose mothers ate a diet rich in omega-3s had higher concentrations of brown fat than those whose mothers did not consume omega-3s. In addition, they had higher energy expenditure and were more efficient at maintaining their core body temperature in cold temperatures. Genetic analysis revealed that the increase in brown fat synthesis was mediated via epigenetic mechanisms. You can learn more about epigenetic mechanisms in our article here.
Brown fat, also known as brown adipose tissue, is found in all mammals and is particularly abundant in newborns. Unlike white fat, brown fat is metabolically active tissue that is rich in mitochondria. It helps maintain body temperature during cold exposure, during which its uptake of glucose is eightfold higher than that of muscle tissues, driving increases in energy expenditure.
Cold exposure increases brown fat activity in humans, possibly benefitting whole-body glucose utilization and insulin sensitivity. Learn more about the effects of cold exposure in our overview article.
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Cold treatment and sympathetic nervous stimulation increases T Regulatory cells (Tregs) in fat tissue: brown fat most of all, visceral least www.sciencedaily.com
From the article:
The number of obese people as well as those suffering from type 2 diabetes is increasing worldwide. Both disorders are associated with metabolic changes including amplified inflammatory responses in adipose tissue. “Previous studies have indicated that immunosuppressive regulatory T-cells – or Tregs for short – play an important role in these processes,”[…]
[They] determined that the number of Tregs in adipose tissue increases in response to different environmental stimuli. These stimuli included a short-term cold treatment, stimulation of the sympathetic nervous system (beta-3-adrenoreceptors) or short-term high-caloric exposure. “All these stimuli supported those immunosuppressive cells directly in the adipose tissue,”
T regulatory cell response to cold and adrenaline reduced in visceral fat:
The magnitude of the increase in Tregs differed depending on the type of adipose tissue: it was particularly pronounced in brown fat, somewhat weaker in subcutaneous fat and weakest in visceral fat.
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Local heat therapy induces browning of adipose tissue in mice and humans, a study finds. www.the-scientist.com
Heat exposure promotes browning of white fat, too.
The color of fat tissue – white, brown, or beige – determines the role the tissue plays in the body. Whereas white fat is involved primarily in lipid storage, brown fat is involved primarily in heat production. Beige fat, which is co-located with white fat, can adopt either storage or heat-producing properties. Cold exposure, which induces hypothermia, causes white fat to convert to beige fat, a process known as “browning” (or “beiging”). Conversely, findings from a recent study suggest that heat exposure, which induces hyperthermia, also promotes browning of white fat.
Hyperthermia is an increase in the body’s core temperature that induces a thermoregulatory response involving neuroendocrine, cardiovascular, and cytoprotective mechanisms. These mechanisms work together to restore homeostasis and condition the body for future heat stressors, a phenomenon known as hormesis. Evidence suggests that hyperthermia is beneficial against metabolic diseases, such as type 2 diabetes and obesity.
The investigators used a photothermal gel that can convert the energy of near-infrared light to heat to induce local hyperthermia. They injected the gel into both sides of the fatty tissues in the groin area of obese mice and applied near-infrared light to one side of the injected area but not the other. The area that received the near-infrared light exposure warmed to 41°C (~5°C higher than normal body temperature for mice), and heat production continued in the exposed area for 12 hours. Then the investigators applied heat to the neck and shoulders of humans, warming the area to 41°C, and found that the tissue continued to produce heat for two hours.
Next, the investigators gauged the effects of local hyperthermia on metabolism. They found that the mice that received the local hyperthermia treatment were thinner, had better insulin sensitivity, and had fewer fat deposits in their livers than the mice that didn’t receive local hyperthermia.
These findings suggest that local hyperthermia treatment induces browning and heat production in white fat in both mice and humans and improves metabolic function in mice, providing a potential means for treating obesity. Learn more about the beneficial effects of hyperthermia in our overview article.
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Circadian rhythms influence brown fat activity. www.nature.com
Circadian rhythms – the body’s daily cycles of biological, hormonal, and behavioral patterns – play critical roles in human health. Disturbances in these rhythms may increase susceptibility to metabolic disorders, such as diabetes and obesity. Findings from a new study indicate that diurnal circadian variations in brown adipose tissue activity may contribute to metabolic disorders.
Brown adipose tissue is a type of fat involved in thermogenesis – the production of body heat. There are two types of thermogenesis: diet-induced and cold-induced. Diet-induced thermogenesis involves an increase in the metabolic rate that occurs after consuming a meal. Cold-induced thermogenesis involves uncoupling electron transport from ATP synthesis and repetitive, non-productive transport of ions across the adipose cell membrane. In the past, scientists believed that brown fat was present only in newborns, where it served to protect against heat loss via cold-induced thermogenesis. However, recent research has identified active brown fat in adults, typically following cold exposure. Brown fat activity contributes to overall energy expenditure and the regulation of body fat.
The authors of the study conducted a two-part investigation. In the first part, 21 healthy men (20 to 50 years old) underwent positron emission tomography (PET) scans to detect the presence of brown fat. During the PET scans, the men sat in a cool (66°F, 19°C) room for two hours while wearing lightweight clothes (a T-shirt and shorts) and periodically placing a towel-wrapped block of ice against the soles of their feet. The authors of the study categorized the men as having high or low quantities of brown fat. Then the men ate a standardized meal, and the authors of the study measured several parameters of the men’s metabolic function, including energy expenditure, diet-induced thermogenesis, and fat oxidation.
They found that men with high quantities of brown fat tended to have higher diet-induced thermogenesis and fat oxidation than those with low quantities, especially after breakfast, suggesting that brown fat has a greater influence on diet-induced thermogenesis earlier in the day.
In the second part of the study, the authors categorized 23 healthy men (20 to 29 years old) as having high or low quantities of brown fat using the same procedure used in the first study. Then they used a thermal imaging camera to measure the men’s skin temperature at the supraclavicular region (just above the collar bones, an area where brown fat is typically present). They took measurements in the morning and evening in warm (80°F, 27°C) conditions and after the men had been sitting for 90 minutes in cool (66°F, 19°C) conditions. They also measured the men’s energy expenditure, cold-induced thermogenesis, and fat oxidation.
They found that the men’s energy expenditure, fat oxidation, and supraclavicular temperature were higher in the men with high quantities of brown fat compared to those with low quantities. The men’s energy expenditure in the morning was nearly equal for both high and low brown fat groups in warm conditions, but it was higher in cool conditions among those with high brown fat quantities. Energy expenditure in the evening was the same among both groups regardless of temperature. Cold-induced thermogenesis among the men with high brown fat quantities was higher in the morning than in the evening.
These findings suggest that brown fat activity exhibits diurnal circadian variations that influence metabolic function. These variations may explain associations between meal timing, obesity, and related metabolic disorders. Time-restricted eating resets the circadian clock to promote metabolic health. Learn more about time-restricted eating in our overview article.
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Brown fat is linked with lower risk of some chronic diseases. www.sciencedaily.com
Obesity, or having excess body fat, is a known risk factor for a wide range of diseases, including diabetes, cancer, and dementia. Findings from a new study indicate that having brown fat is linked with lower risk of some chronic diseases.
Brown fat, also known as brown adipose tissue, is found in all mammals and is particularly abundant in newborns. Unlike white fat, brown fat is a metabolically active tissue that is rich in mitochondria. It helps maintain body temperature during cold exposure, during which its uptake of glucose is eightfold higher than that of muscle tissues.
The authors of the retrospective case-control investigation reviewed imaging reports from more than 52,000 adults who had undergone diagnostic positron emission tomography (PET) scans (nearly 135,000 total scans). They also reviewed the participants' health records.
The PET scans revealed that nearly 10 percent of the study participants had detectable brown fat. Those who had brown fat were less likely to have type 2 diabetes, abnormal lipid levels, coronary artery disease, cerebrovascular disease, congestive heart failure, and hypertension. They were also more likely to have favorable blood glucose, triglyceride, and high-density lipoprotein levels. These effects were greatest in people who had obesity or overweight. The authors suggested that having brown fat might counteract some of the harmful effects of obesity.
These findings indicate that brown fat may protect against some diseases and suggest that adopting lifestyle behaviors that promote production of brown fat, such as exercise or cold exposure, may be beneficial. Some nutrients and bioactive compounds, such as curcumin, capsaicin, resveratrol, and omega-3 fatty acids, may increase brown fat production, too.