Using the Power of Fermentation for Your Gut Health


For many who read the recent Stanford study on the relative benefits of fermented vs. plant-based high-fiber diets (see “Gut-microbiota-targeted diets modulate human immune status,” Cell, July 2021*), it came as a surprise that test subjects who increased their intake of fermented foods showed greater improvement in gut microbiota diversity than those on a high-fiber diet.  This exhaustive study measured levels of various types of gut bacteria, as well as immune response and inflammatory markers, over a period of several weeks.

The researchers did not determine the causal factor for fermented foods outperforming the high-fiber diet, except to say that the high-fiber diet might require additional gut microbes “to increase the microbiota's fermentative capacity.”  Meanwhile, the study also noted that those on the fermented food diet showed a decrease in inflammatory markers, along with inceased biotic activity.

The study allowed participants to choose which types of fermented or high-fiber foods they ate, with considerable variety allowed.  For instance, the fermented foods in the test included:

  • Kefir and yogurt
  • Brine drinks, like kombucha
  • Cultured cottage cheese
  • Fermented vegetables, such as kimchi

The Stanford study produced plenty of interesting evidence to guide future research on the role of diet in our health, and offers a few important take-aways for everyone concerned with improving their digestive balance:  (1) Fermented foods are unquestionably linked to vigorous biotic activity in the gut; (2) going on a crash high-fiber diet might be counterproductive for those suffering from digestive issues, and; (3) fermented foods can be used to modify the gut microbiome in just a matter of weeks.

Perhaps it goes without saying, but diet – not medicine, rather the interaction of the foods we eat with our bodies – can produce dramatic changes not only in our digestive systems, but on our health in general.  As the study observes: “manipulation of gut microbes may be a powerful means to alter diverse aspects of human health.”


*The full Stanford study, including charts and tables, is available for purchase on A text version can be found at:

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