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Fermented foods are foods made when microbes such as bacteria, yeasts or molds grow in them on purpose and change their sugars, proteins or fats. Yogurt, kefir, sauerkraut, kimchi, miso, tempeh, kombucha and sourdough bread all count. The most-cited study, a small Stanford trial, found that a diet rich in fermented foods raised the variety of gut microbes and lowered several blood markers of inflammation over 10 weeks. That is promising but early evidence, and not every fermented food still contains live microbes by the time you eat it. Here is a fermented foods list, what the studies show, and who should be careful.
Peptide Labs sells supplements, including one gummy that lists kombucha powder, but this article does not recommend any of them. It is general information, not medical advice.
Key Takeaways
- A 2021 expert panel defined fermented foods as foods made through desired microbial growth and conversion.
- Fermented foods are not automatically probiotics, and baked or pasteurized ones have few or no live microbes.
- A small 10-week Stanford trial linked a high fermented food diet to more microbe variety and less inflammation.
- A larger 2025 sauerkraut trial in healthy adults found only small changes in gut microbes.
- Salt, histamine, tyramine and alcohol are the main cautions, especially with MAOI antidepressants.
What counts as fermented foods?
In 2021 the International Scientific Association for Probiotics and Prebiotics (ISAPP) published a consensus statement that defines fermented foods as “foods made through desired microbial growth and enzymatic conversions of food components.” The word desired matters: spoiled food also has microbial growth, but nobody planned it. The panel also notes that some vinegars and soy sauces are made by chemical processes instead, so the label name alone does not tell you how a food was made.
The panel drew a clear line between fermented foods and probiotics. A probiotic is a defined, live microbe with evidence of a health benefit. Most fermented foods contain a changing mix of unnamed strains, so they do not meet that bar even when they are full of live bacteria. Our guide to prebiotics vs probiotics explains the related terms.
Fermented foods list
Different microbes drive different foods. Lactic acid bacteria make most fermented dairy and vegetables, yeasts make bread rise and produce alcohol, molds start miso and soy sauce, and acetic acid bacteria turn alcohol into vinegar. This table covers common options in US stores:
| Food | Made from | Main microbes | Live microbes when eaten? |
|---|---|---|---|
| Yogurt | Milk | Lactic acid bacteria | Usually, unless heat-processed after culturing |
| Kefir | Milk | Bacteria and yeasts from kefir grains | Usually |
| Sauerkraut | Cabbage and salt | Leuconostoc, then Lactiplantibacillus | Refrigerated raw: yes; canned: few or none |
| Kimchi | Napa cabbage, radish, seasonings | Same lactic acid bacteria sequence | Usually, if sold chilled |
| Miso and soy sauce | Soybeans and grains | Koji molds | Varies; cooking kills them |
| Natto | Whole soybeans | Bacillus subtilis | Usually |
| Tempeh | Soybeans | Molds | Few, because it is cooked |
| Kombucha | Sweetened tea | Bacteria and yeasts (SCOBY) | Often, unless pasteurized |
| Sourdough bread | Flour and water | Yeasts and lactic acid bacteria | No, baking kills them |
The same microbes show up in fermented cabbage around the world. The ISAPP statement notes that cabbage fermentations are started by Leuconostoc mesenteroides and finished by Lactiplantibacillus and Levilactobacillus species whether the result is called sauerkraut, kimchi or suan-cai. Our sauerkraut guide covers that food in detail.
Fermented foods benefits: what the research shows
The study most often quoted is a 2021 Stanford trial in the journal Cell. Healthy adults were randomly assigned to eat more fiber or more fermented foods for 10 weeks, as part of a 17-week study. The fermented group added yogurt, kefir, fermented cottage cheese, kombucha, vegetable brine drinks and fermented vegetables such as kimchi, working up to several servings a day. In that group, gut microbe diversity rose steadily and 19 of 93 inflammatory proteins measured in the blood went down, including interleukin 6. The high-fiber diet did not raise diversity.
The limits matter. Only 36 people were analyzed, most were women with college degrees, the study’s main planned outcome (a measure of immune cell signaling) did not change, and some authors have ties to microbiome companies. The results suggest fermented foods are worth a place in the diet; they do not prove that any single food changes health. Our article on how to improve gut health puts this trial next to the other food habits with research behind them.
| Study | Who and how long | What it found | Limits |
|---|---|---|---|
| Stanford fermented food diet (2021) | 36 healthy adults, 10 weeks | More microbe diversity; 19 inflammatory markers lower | Small; main outcome unchanged |
| Fresh vs pasteurized sauerkraut (2025) | 87 healthy adults, 4 weeks each | Changes in single species only | Short; healthy people |
| Same sauerkraut trial, blood markers (2026) | 87 healthy adults | Small drop in systolic blood pressure | No broad health benefit seen |
| ISAPP review (2021) | Expert panel | Kefir, kimchi, sauerkraut, natto, vinegar, sourdough each tested in at least one trial | Few large trials; panel has industry ties |
A larger German crossover trial tempered expectations. Its 87 healthy adults ate fresh or pasteurized sauerkraut daily for four weeks each. The researchers saw changes in single bacterial species but described the gut microbiome as “rather resilient” to short-term diet changes. A follow-up analysis found a small drop in systolic blood pressure with both versions but no appreciable overall health benefit. The ISAPP panel adds that most evidence for yogurt comes from observational studies, which cannot show cause and effect.
Live vs pasteurized: reading the label
Heat kills microbes. Bread is baked after fermentation, canned sauerkraut is usually pasteurized, and some yogurts are heat-processed after culturing. These are still fermented foods and keep the acids, flavors and fiber that fermentation created; they just contain few or no live microbes. The German trial found that pasteurized sauerkraut produced as much or more change as fresh, so live bacteria are not the whole story.
- “Live and active cultures”: ISAPP says this wording should appear only when the food was not processed to kill or remove the fermentation microbes.
- Refrigerated vs shelf-stable: raw sauerkraut, kimchi and kombucha sold chilled are more likely to contain live microbes than shelf-stable jars and cans.
- “Probiotic” claims: ISAPP says a fermented food should be called probiotic only when it contains a defined strain with evidence, at an effective level until the end of shelf life.
- Added cultures: some brands add microbes back after heat processing, so check the ingredient list.
Who should be careful with fermented foods
- People watching sodium: salt is part of sauerkraut, kimchi, miso and soy sauce, and ISAPP advises moderation. Check the Nutrition Facts label.
- People who react to histamine: a 2020 review notes that fermenting bacteria can produce histamine, and low-histamine diets routinely exclude fermented products, although experts do not agree on one food list.
- People taking MAOI antidepressants: the prescribing information for phenelzine (Nardil) lists sauerkraut, most cheeses, yogurt, beer and wine among foods to avoid during use and for two weeks after stopping, because tyramine can raise blood pressure dangerously.
- People avoiding alcohol: kombucha and some other fermented drinks contain small amounts. Our kombucha guide covers the details.
- New eaters: gas and bloating can happen when you add a lot at once. Starting small and building up slowly is a sensible approach.
Fermented foods vs supplements
A fermented food is a whole food with fiber, acids and a mixed, unlabeled set of microbes. A probiotic supplement lists named strains and a count. Neither is a substitute for the other, and the evidence for each is specific to the food or strain tested. Some gummies borrow fermented ingredients: BoochBod Probiotic Kombucha Gummies list kombucha powder made from fermented black tea among the other ingredients, without stating an amount, along with the LactoSpore Bacillus coagulans probiotic and 2 grams of added sugar per gummy. It is a dietary supplement, not a fermented food.
Frequently Asked Questions
What are fermented foods?
Foods made when microbes grow in them on purpose and convert some of their components, such as yogurt, kefir, sauerkraut, kimchi, miso, tempeh, kombucha and sourdough bread.
What is a good fermented foods list to start with?
Common options in US stores are yogurt, kefir, refrigerated sauerkraut, kimchi, miso, natto, tempeh and kombucha. Choose foods you enjoy and can eat regularly.
What are the benefits of fermented foods?
A small 2021 Stanford trial linked a high fermented food diet to more gut microbe diversity and lower inflammatory markers. Larger, longer trials are still needed.
Are all fermented foods probiotic?
No. Many are baked or pasteurized, and even live ones usually contain unnamed strains without proven benefits, so experts do not call them probiotics.
Do pasteurized fermented foods still help?
They keep the acids and fiber made during fermentation. In one sauerkraut trial, the pasteurized version changed gut microbes as much as the fresh one.
Who should avoid fermented foods?
People taking MAOI antidepressants, people on low-sodium or low-histamine diets, and anyone told by a clinician to limit them should check first.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement or making a big change to your diet, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Kefir Benefits: What Kefir Is, the Evidence and Kefir vs Yogurt, Kombucha Benefits: What Human Studies Show, Risks, and Gummies vs the Drink, How to Improve Gut Health: Evidence-Based Habits and What Tests Can’t Tell You, Nattokinase: Benefits, Side Effects and Bleeding Risks.