Should I eat fermented foods?

Our read is that ingesting fermented foods is a superior method for adjusting the gut microbiome and reducing inflammatory markers compared to a high-fiber diet alone, according to Andrew Huberman and Paul Saladino.

Andrew Huberman and Paul Saladino indicate that consuming fermented foods increased gut microbiota diversity in humans living in the industrialized world, and Andrew Huberman recommends regular daily ingestion of various fermented foods to reduce inflammatory markers, improve autoimmune function, and adjust gut chemistry.

However, Paul Saladino cautions that certain fermented foods like kimchi and sauerkraut may have drawbacks, and Andrew Huberman warns against overconsumption or improper preparation.

Andrew Huberman suggests consuming 5-6 servings daily of low-sugar fermented foods for six weeks, with recommended serving sizes including 6-8 ounces of kombucha and half a cup of sauerkraut or yogurt. Andrew Huberman also advises a gradual ramp-up when consuming fermented food brine to avoid digestive distress. Paul Saladino notes that kefir is fermented for 14-18 hours at room temperature, while yogurt is fermented for 2-4 hours at a slightly heated temperature.

• 01A study found that a high fermented food intervention yielded a significant biological signal, while a high fiber intervention did not (Andrew Huberman, 1x).
• 02Consuming kefir for 4 weeks resulted in a more than 2-fold increase in beneficial lactobacillus bacteria and improved relational memory compared to a placebo (Rhonda Patrick, 1x).
• 03Ingesting fermented foods is a superior method for adjusting the gut microbiome and reducing inflammatory markers compared to a high-fiber diet alone (Andrew Huberman, Paul Saladino, 7x).
• 04Interventions with fermented foods, but not fiber, increased alpha diversity of the gut microbiome (Andrew Huberman, Paul Saladino, 4x).
• 05Low-sugar fermented foods can improve gut microbiome health, reduce inflammation, and benefit brain and body health (Andrew Huberman, 6x).
• 06A clean diet focusing on high-quality protein, vegetables, limited fruit, nuts, seeds, olives, pickles, and fermented foods supports oral microbiome health (Andrew Huberman, Bryan Johnson, 2x).
• 07Fermented foods like kimchi and live sauerkraut are beneficial due to short-chain fatty acid production (Andrew Huberman, 1x).
• 08Some individuals report improved mood from consuming small amounts of fermented foods (Andrew Huberman, 2x).
• 09Consuming fermented foods increased gut microbiota diversity in humans living in the industrialized world (Andrew Huberman, Paul Saladino, 9x).
• 10A decrease in fiber and fermented food intake led to a plateau and reversal of gut microbial diversity in a dietary intervention study (Andrew Huberman, 1x).
• 11Regular daily ingestion of various fermented foods is recommended to reduce inflammatory markers, improve autoimmune function, and adjust gut chemistry (Andrew Huberman, 5x).
• 12Ingesting fermented foods is a way to support healthy gut microbiota levels without exceeding a threshold that could cause brain fog (Andrew Huberman, 3x).
• 13Kefir has more diverse bacterial and eukaryotic strains and is fermented longer at room temperature compared to yogurt (Paul Saladino, 2x).

Paul Saladino warns that kombucha made with large amounts of unfermented sugar can be detrimental to the gut in animal models. Paul Saladino also suggests that focusing solely on alpha diversity in gut microbial studies may be misleading, as fiber does not consistently increase alpha diversity, improve inflammation, or enhance the immune system, whereas fermented foods do. Paul Saladino states that fermented sauerkraut is not the best source of fermented foods because it is made from cabbage, which contains defense chemicals like isothiocyanates. Paul Saladino notes that fermented foods may have higher levels of histamine, potentially triggering histamine insensitivity in individuals with insufficient diamine oxidase (DAO). Paul Saladino indicates that kimchi is not considered good for the gut because it contains capsicum spices, which appear to open tight junctions in cell culture. Paul Saladino cautions that overconsumption of highly acidic fermented foods or acidic citrus fruits can erode tooth enamel and harm gums. Andrew Huberman warns that consuming a large quantity of fermented food brine without a gradual ramp-up can lead to significant digestive distress. Andrew Huberman also notes that improperly prepared homemade sauerkraut can grow dangerous bacteria, but proper scraping of the top layer mitigates this risk. Paul Saladino states that mass-produced sauerkraut and pickles in grocery stores are often of poor quality.

A study is needed to investigate the impact of consuming 5-6 servings daily of low-sugar fermented foods for six weeks on depressive symptoms, according to Andrew Huberman. Rhonda Patrick notes that preliminary findings suggesting kefir may improve gut bacteria and memory require confirmation in larger studies.