Following a diet high in fermented foods for just 10 weeks was linked to a more diverse gut microbiome and improved immune system response, as well as lower levels of inflammation, in a new study published in the journal Cell.
Researchers at Stanford University’s School of Medicine led a clinical trial with 36 healthy adults as participants, as described in a news release from the school. Participants were randomly assigned to follow a diet for 10 weeks that that included either fermented or high-fiber foods. Both fermented and high-fiber foods may have benefits related to the gut microbiome — the millions of bacteria that live in your digestive system. Fermented foods — such as yogurt, kefir, fermented cottage cheese, kimchi and other fermented vegetables, and kombucha tea — actually contain beneficial bacteria, while dietary fiber — a form of carbohydrate that isn’t readily broken down by digestive juices or enzymes — serves as food for healthy bacteria, allowing them to multiply in the colon (large intestine).
To get cutting-edge diabetes news, strategies for blood glucose management, nutrition tips, healthy recipes, and more delivered straight to your inbox, sign up for our free newsletters!
Fermented foods linked to an increase in microbial diversity
Not surprisingly, each of the two diets in the study was linked to certain indicators of digestive and overall health. Consuming fermented foods was linked to an increase in microbial diversity, with a stronger effect seen from eating larger quantities of these foods. A more diverse gut microbiome is linked to a healthier digestive system and overall immune system, as seen in another finding — that four types of pro-inflammatory immune cells showed less activation in participants who ate fermented foods. People in this group also had lower levels of 19 different inflammatory proteins in their blood. One of these proteins, interleukin 6 (IL 6), is linked to chronic health conditions, including type 2 diabetes and rheumatoid arthritis.
“This is a stunning finding,” said study author Justin Sonnenburg, PhD, in the news release. “It provides one of the first examples of how a simple change in diet can reproducibly remodel the microbiota across a cohort of healthy adults.”
In contrast, following a high-fiber diet — rich in legumes, seeds, whole grains, nuts, vegetables, and fruits — didn’t lead to any increase in microbiome diversity. What’s more, participants in this group didn’t experience any overall reduction in the 19 inflammatory proteins that the researchers tested for. The researchers had expected that microbial diversity would increase in this group as well, so these results were somewhat unexpected. Still, the high-fiber diet was linked to some beneficial effects, including a healthier immune response in participants who already had a more diverse microbiome.
This study didn’t look at the combined effect of consuming both fermented and high-fiber foods. It’s possible that increasing both of these food groups in your diet could lead to even greater health benefits than those seen from fermented foods alone, but more research is needed to see if this is the case. In the meantime, “Fermented foods may be valuable in countering the decreased microbiome diversity and increased inflammation pervasive in industrialized society,” the researchers concluded.
Living with type 2 diabetes? Check out our free type 2 e-course!