Low-carb, high-fat ketogenic diets, which have attracted public curiosity in current years for his or her proposed advantages in decreasing irritation and selling weight reduction and coronary heart well being, have a dramatic influence on the microbes residing in the human gut, collectively known as the microbiome, based on a brand new UC San Francisco examine of a small cohort of volunteer topics. Additional analysis in mice confirmed that so-called “ketone bodies,” a molecular byproduct that offers the ketogenic weight loss program its identify, straight influence the gut microbiome in ways in which could in the end suppress irritation, suggesting proof for potential advantages of ketone our bodies as a remedy for autoimmune problems affecting the gut.
In ketogenic diets, carbohydrate consumption is dramatically diminished in order to drive the physique to alter its metabolism to utilizing fats molecules, moderately than carbohydrates, as its main vitality supply—producing ketone our bodies as a byproduct—a shift that proponents declare has quite a few well being advantages.
“I got interested in this question because our prior research showed that high-fat diets induce shifts in the gut microbiome that promote metabolic and other diseases in mice, yet ketogenic diets, which are even higher in fat content, have been proposed as a way to prevent or even treat disease,” mentioned Peter Turnbaugh, Ph.D., a UCSF affiliate professor of microbiology and immunology, member of the us Benioff Center for Microbiome Medicine and a Chan Zuckerberg Biohub Investigator. “We decided to explore that puzzling dichotomy.”
In their new examine, printed May 20, 2020, in Cell, Turnbaugh and colleagues partnered with the nonprofit Nutrition Science Initiative to recruit 17 grownup obese or overweight nondiabetic males to spend two months as inpatients in a metabolic ward the place their diets and train ranges have been fastidiously monitored and managed.
For the primary 4 weeks of the examine, the members got both a “standard” weight loss program consisting of 50 % carbs, 15 % protein and 35 % fats, or a ketogenic weight loss program comprising 5 % carbs, 15 % protein and 80 % fats. After 4 weeks, the 2 teams switched diets, to permit the researchers to check how shifting between the 2 diets altered members’ microbiomes.
Analysis of microbial DNA discovered in members’ stool samples confirmed that shifting between commonplace and ketogenic diets dramatically modified the proportions of frequent gut microbial phyla Actinobacteria, Bacteroidetes, and Firmicutes in members’ guts, together with vital adjustments in 19 completely different bacterial genera. The researchers centered in on a specific bacterial genus—the frequent probiotic Bifidobacteria—which confirmed the best lower on the ketogenic weight loss program.
To higher perceive how microbial shifts on the ketogenic weight loss program may influence well being, the researchers uncovered the mouse gut to completely different elements of microbiomes of people adhering to ketogenic diets, and confirmed that these altered microbial populations particularly scale back the numbers of Th17 immune cells—a kind of T cell important for preventing off infectious illness, but additionally recognized to advertise irritation in autoimmune illnesses.
Follow-up weight loss program experiments in mice, in which researchers progressively shifted animals’ diets between low-fat, high-fat and low-carb ketogenic diets, confirmed that high-fat and ketogenic diets have reverse results on the gut microbiome. These findings advised that the microbiome responds otherwise as the extent of fats in the animals’ weight loss program will increase to ranges that promote ketone physique manufacturing in the absence of carbs.
The researchers noticed that that as animals’ diets have been shifted from an ordinary weight loss program in the direction of stricter carbohydrate restriction, their microbes additionally started shifting, correlated with a gradual rise in ketone our bodies.
“This was a little surprising to me,” Turnbaugh mentioned. “As someone who is new to the keto field, I had assumed that producing ketone bodies was an all-or-nothing effect once you got to a low enough level of carb intake. But this suggests that you may get some of the effects of ketosis quite quickly.”
The researchers examined whether or not ketone our bodies alone may drive the shifts that they had seen in the gut’s microbial ecosystem by straight feeding ketone our bodies to mice. They discovered that even in mice who have been consuming regular quantities of carbohydrates, the mere presence of added ketones was sufficient to supply lots of the particular microbial adjustments seen in the ketogenic weight loss program.
“This is a really fascinating finding because it suggests that the effects of ketogenic diets on the microbiome are not just about the diet itself, but how the diet alters the body’s metabolism, which then has downstream effects on the microbiome,” Turnbaugh mentioned. “For many people, maintaining a strict low-carbohydrate or ketogenic diet is extremely challenging, but if future studies find that there are health benefits from the microbial shifts caused by ketone bodies themselves, that could make for a much more palatable therapeutic approach.”
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Ketogenic diets alter gut microbiome in people, mice (2020, May 20)
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