You often hear about yogurt and fermented foods being good for your gut, but new research suggests they may do more than that.
Scientists at Stanford University believe that yogurt and other fermented foods including kefir, kimchi, cottage cheese, and kombucha not only support good gut bacteria but may also aid in preventing the inflammation that kickstarts arthritis and diabetes.
According to the study authors, an increase in overall gut microbial diversity was observed when these foods are consumed, with larger effects from bigger servings. Nineteen markers of inflammation known as inflammatory proteins also declined with the addition of fermented foods.
Interleukin 6, an inflammatory protein, is linked with rheumatoid arthritis, type 2 diabetes, and prolonged stress. Justin Sonnenburg, PhD an associate professor of microbiology and immunology states that this is “one of the first examples of how a simple change in diet can reproducibly remodel the microbiota across a cohort.”
Researchers discovered the benefits of fermented foods while doing a comparison study on the impact of diets high in fiber and high in fermented foods. Lower rates of mortality are associated with a high-fiber diet, but none of the 19 inflammatory proteins were decreased with a high-fiber diet. Gut diversity was unchanged with intake of beans, seeds, whole grains, fruits, and vegetables.
The researchers were surprised that a high-fiber diet didn’t increase microbiota diversity despite it being linked with lower mortality. Dr. Christopher Gardner, a professor of medicine at Stanford, maintains that the research was done to investigate the role of microbiota-targeted food and chronic inflammatory diseases.
Blood and stool samples were collected and analyzed during a 3-week pre-trial time, then at 10 weeks of the diet and a 4-week post diet time when subjects ate what they wanted. Subjects who consumed more fermented food had similar effects on the diversity of their microbiome as well as inflammatory markers. This was consistent with previous research highlights that, short-term changes could alter the gut microbiome.
The study also found that higher fiber intake resulted in higher carbohydrates in stool samples, indicating incomplete fiber digestion by gut microbes. The scientists point out that their findings were similar to other studies that suggested that the gut microbiota of those living in the industrialized world is lacking fiber-degrading microbes.
Dr. Sonnenburg suggests, “It’s possible that a longer intervention would have allowed for the microbiota to adequately adapt to the increase in fiber consumption.” She also notes that adding fiber-consuming microbes may be necessary to increase the microbiota’s ability to properly break down carbohydrates.
Future plans for the Stanford researchers include studies on mice to evaluate the molecular mechanisms on how diets alter the microbiome and lower inflammatory proteins. They also plan to investigate if high-fiber and fermented foods work synergistically to impact the microbiome and immune system
They may also study the effect on the intake of fermented food and inflammation and improvements of other health conditions in patients with immune and metabolism disorders, pregnant women, and older people.
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By Lisa Andrews, MEd, RD, LD
Wastyk HC, Fragiadakis GK, Perelman D, Dahan D, Merrill BD, Yu FB, Topf M, Gonzalez CG, Van Treuren W, Han S, Robinson JL, Elias JE, Sonnenburg ED, Gardner CD, Sonnenburg JL. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021 Jul 6:S0092-8674(21)00754-6.
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.