If you’ve ever lumped kombucha in with other buzzy foods boasting dubious health claims — think gluten-free cookies or agave nectar — it may be time to reconsider.
Scientists examined study participants’ gut health before, during, and after eating a diet high in fermented foods and found marked changes. These changes suggest eating a similar diet could lead to dramatic health benefits. This finding was published on July 12 in the journal Cell.
“The result that an increase in fermented foods leads to a decrease in circulating inflammatory markers across an entire cohort of healthy adults is something that people haven't seen before,” lead author Hannah Wastyk tells Inverse. Wastyk is a bioengineering Ph.D. student at Stanford University.
“That was absolutely incredible result, and I think probably better than anyone had really anticipated,” Wastyk says.
SCIENCE IN ACTION — Wastyk and colleagues split up 36 participants into two groups. One group ate a diet high in fiber, and the other a diet high in fermented foods.
The study team examined stool and blood samples from the participants:
- Before the diets
- Throughout a 4-week “ramp up” phase, where they increased consumption
- During a 6-week “maintenance” phase
- Afterward, where they could choose what they ate for 4 weeks
They found that during the study, the high-fermented foods group:
- Increased biodiversity — the number of distinct microbes in their gut over time
- Decreased levels of 19 proteins in the blood associated with inflammation
- Decreased activity in four kinds of immune cells in the blood, indicating that they weren’t working overtime to respond to inflammation
One of the proteins that decreased, a cytokine called IL-6, is associated with chronic diseases like Type-2 diabetes, rheumatoid arthritis, and chronic stress. The results, the researchers said, were significant.
“The fact that in the entire cohort of the fermented food diet, we saw improvements of immune status — yeah, just stunning,” Wastyk says.
The high-fiber dieters, for their part, had no overall change in their gut microbiome diversity. However, gut bacteria that help with the breakdown of fiber increased.
During the fermented foods diet, participants increased their average consumption of less than one serving a day to around 6 servings a day. They ate fermented foods of their choosing, including yogurt, kimchi, fermented vegetables, kefir, and kombucha.
One of the most popular options, Wastyk says, was a “brine” drink: “Basically what's left at the bottom of your jar of sauerkraut,” she says. Some participants took the brine drink like a shot to meet their serving quota.
HOW THIS AFFECTS LONGEVITY — Inflammation is a general term that means an immune response to what your body perceives as a threat.
Some inflammation is necessary to heal an infection or fight back against a cold. Too much of it is linked with several chronic diseases, including diabetes, autoimmune disorders, and metabolic disorders.
Lower markers of inflammation, like the immune cells and proteins observed in the study, suggest the body is perceiving fewer threats and isn’t overreacting.
Low microbiome diversity and high inflammation are linked to some chronic health problems, like diabetes and obesity, and “industrialized” lifestyles are also thought to predispose people to the same conditions. Decreasing inflammation, like was observed in this study, could promise to prevent chronic disease in the future.
Wastyk says the team wants to try a similar diet with more inflammation than this study: pre-diabetes, intestinal bowel disorder, or other conditions. “If the same trend would hold, that would be great because then it can be used for the treatment of disease,” she says.
“If the result doesn't translate, then perhaps we can think about this as a preventative measure against the development of chronic diseases in the future,” Wastyk says.
WHY IT'S A HACK — Eating more fermented foods is known to be a relatively easy, low-cost way to improve gut health. This study serves to support this claim, drawing a clear link between foods like kimchi and kefir to increased gut bacteria diversity and decreased inflammation.
The slow introduction of fermented foods resulted in these positive changes — signaling that it’s not so difficult to make this change.
What’s more, it seems as if the fermented foods didn’t necessarily introduce “new” bacteria into the gut, suggesting the microbiome can be “remodeled” with the introduction of fermented foods.
HACK SCORE OUT OF 10 — 🥒🥒🥒🥒🥒🥒 (6/10)