03/01/2026
Your gastrointestinal (GI) tract responds to what you feed your microbes.
When you nourish your gut microbiome with the foods it thrives on, you help create a healthy gut environment and a more supportive immune system.
In a randomized controlled trial published in Cell (Wastyk et al., 2021), participants who increased fermented food intake over 10 weeks experienced a significant increase in gut microbiome diversity. Around 19 inflammatory markers decreased, including IL-6 and multiple immune signaling pathways involved in chronic inflammation.
The high-fiber group (that did not consume fermented foods) in the same study did not show the same increase in microbiome diversity during that timeframe.
Why does this matter for gut health and immune health?
Your gut microbiome directly regulates immune function. Research shows gut bacteria influence T-cell development, cytokine production, systemic inflammation, and overall immune balance. Lower microbial diversity, which is often associated with an American-style diet high in ultra-processed foods, is linked with autoimmune disease, metabolic dysfunction, and chronic inflammatory conditions. Greater microbiome diversity is associated with stronger immune regulation and resilience to chronic disease.
In the study, participants gradually increased to about 6 servings of fermented foods per day (½ cup yogurt, kefir, sauerkraut, kimchi, cottage cheese, or kombucha counted as one serving). Intake was increased slowly over 4 weeks and maintained for 6 more.
For most people, 1–3 servings per day is a realistic starting point. This typically means incorporating 1 & 1/2 cups of fermented foods daily.
Disclaimer: This content is for educational purposes only and is not medical advice.
References
Wastyk HC et al. Cell. 2021;184(16):4137–4153.e14. doi:10.1016/j.cell.2021.06.019
Belkaid Y & Hand TW. Cell. 2014;157(1):121–141. doi:10.1016/j.cell.2014.03.011
Zmora N et al. Nat Rev Gastroenterol Hepatol. 2019;16:35–56. doi:10.1038/s41575-019-0193-8
Lloyd-Price J et al. Genome Med. 2016;8:51. doi:10.1186/s13073-016-0307-y