What Is in Them, What Research Shows & What to Check.
Fermented foods are food first. Explore each one: how it is made, whether it still has live cultures, what research in people has and has not found, a normal serving, and what to check before you eat it: histamine, sodium, pregnancy and unpasteurized products, medicines, and allergies. Foods are kept apart from probiotic supplements.
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Lactic-fermented milk
Vitamin B12Riboflavin (B2)CalciumPhosphorusProtein
Normal serving (USDA): 1 cup (8 fl oz), 245 g
What research says about yogurt as a food: lactose digestion, observational links with health, a small cholesterol trial base, what live cultures mean, and label and pregnancy cautions.
Fermented milk drink (kefir grains)
Vitamin AVitamin B12Riboflavin (B2)CalciumProtein
Normal serving (USDA): 1 cup, 243 g
What a 2023 review of 16 human trials found for fermented-milk kefir, why the evidence is limited and often low quality, and cautions for pregnancy and weakened immunity.
Cheddar, Parmesan, Swiss, Gouda
CalciumSeleniumVitamin B12ProteinVitamin A
Normal serving (USDA): 1 ounce (28.35 g), about one slice
Aged cheese (cheddar, Parmesan, Swiss, Gouda) as a fermented food: USDA nutrients, cholesterol trials, and sodium, pregnancy, histamine, tyramine and milk allergy cautions.
Cultured milk
Riboflavin (B2)CalciumVitamin B12PhosphorusProtein
Normal serving (USDA): 1 cup, 245 g
Cultured buttermilk as a food: USDA nutrients per cup, what small studies found on cholesterol and blood pressure, and sodium, lactose, pregnancy and milk allergy cautions.
Strained fermented milk
Normal serving (USDA): Use the Nutrition Facts serving on the package (no USDA household portion in our data)
Skyr and quark, thick fermented milks: what small trials found on protein, fullness and muscle, composition we could verify, and lactose, pregnancy and allergy cautions.
Yogurt drinks
Normal serving (USDA): Use the Nutrition Facts serving on the package (no USDA household portion in our data)
Lassi and ayran, two yogurt drinks: what we could verify about their salt and sugar, one small gum-health trial, and lactose, pregnancy, sodium and milk allergy cautions.
Fermented soybean paste, Aspergillus oryzae koji, Glycine max
Normal serving (USDA): 1 tablespoon (17 g)
Miso is a salty fermented soybean paste. What reviews and cohort studies found, why sodium and soy allergy matter, and why miso is not automatically a probiotic food.
Fermented soybeans (Bacillus subtilis), Glycine max
CopperManganeseIronProteinZinc
Normal serving (USDA): 1 cup (175 g)
Natto is a Japanese fermented soybean food rich in vitamin K2. Read the warfarin caution first, then what studies found on bone markers and mortality, and the soy allergy point.
Fermented soybean cake (Rhizopus), Glycine max
CopperManganeseProteinRiboflavin (B2)Phosphorus
Normal serving (USDA): 1 cup (166 g)
Tempeh is a firm fermented soybean cake from Indonesia. What reviews say, why human evidence is limited, and the allergy and fermentation-safety points to know.
Fermented soy and wheat sauce (shoyu), Fermented soy sauce (tamari)
Normal serving (USDA): 1 tablespoon (16 g) soy sauce with wheat; tamari 1 tablespoon is 18 g
Soy sauce and tamari as foods: USDA sodium values, wheat and gluten, soy allergy, MAOI medicines and histamine, plus what research does and does not show.
Fermented tofu (sufu, furu, fuyu)
Normal serving (USDA): 1 block (11 g)
Fermented tofu (sufu, furu, fuyu) as a food: USDA sodium values, histamine and tyramine, homemade botulism cases, soy allergy and what research does not show.
Korean fermented pastes, Gochujang (chili-soybean paste), Doenjang (soybean paste)
Normal serving (USDA): No USDA household portion; check the label serving size
Gochujang and doenjang, Korean fermented soy pastes: salt, histamine and Bacillus cereus findings, soy allergy, MAOI medicines and what the research really shows.
Oryza sativa, Vigna mungo
Normal serving (USDA): No official serving size found; the glycemic load study used 250 g
Idli and dosa are South Indian cakes made from fermented rice and black gram batter: what lab studies measured, blood sugar, gluten, rice arsenic and what is not proven.
Eragrostis tef
ManganeseCopperThiamin (B1)MagnesiumIron
Normal serving (USDA): 1 cup cooked teff grain (252 g); USDA lists no injera portion
Injera is a sour, spongy Ethiopian flatbread from fermented teff: USDA values for teff, what fermentation does to phytate and iron, gluten and celiac questions, and safety.
Aspergillus oryzae, Oryza sativa
Normal serving (USDA): No official serving size found
Koji is rice grown with the mold Aspergillus oryzae; amazake is the sweet drink made from it. What trials found on bowels and skin, sugar, mold safety and labels.
Secale cereale (rye bread), Saccharomyces cerevisiae, lactic acid bacteria
Normal serving (USDA): 1 glass, 240 mL (about 1 cup); no official serving, used for arithmetic only
Kvass is a lightly sour, fizzy drink fermented from rye bread. What one lab study measured for alcohol, sugar and fiber, and safety points on gluten, sugar and alcohol.
Water kefir grains (Lactobacillus spp., acetic acid bacteria and yeasts)
Normal serving (USDA): 200 mL a day was the amount in a 2026 trial; no official serving size
Water kefir (tibicos) is a dairy-free fizzy drink fermented from sugar water and kefir grains: what a 2026 trial found, trace alcohol, sugar and who should be careful.
Fermented fish (often anchovy) and salt
Normal serving (USDA): 1 tablespoon (about 15 mL); no official serving size, used for arithmetic only
Fish sauce is a salty, savory liquid from fermented fish. A 2025 study of 38 bottles measured sodium and histamine; see what that means for blood pressure, allergy and MAOIs.
Capsicum spp., lactic acid bacteria
Normal serving (USDA): No official serving size found; usually used by the drop or teaspoon
Fermented hot sauce is chili mash soured by lactic acid bacteria in salty brine: what lab studies measured, the sodium and heartburn questions, and what is not proven.
Olea europaea
Table olives (Olea europaea) as a food: USDA nutrients, why brining makes them high in sodium, what research does and does not show, and safety notes.
Brassica rapa subsp. pekinensis (fermented)
Kimchi, a traditional Korean fermented vegetable dish: what small human trials found, why a kimchi-derived probiotic is a different product, and sodium and biogenic amine cautions.
Brassica oleracea var. capitata (fermented)
What an 87-person crossover trial found for fresh and pasteurized sauerkraut, why live cultures were not required for the changes seen, and sodium, biogenic amine and pregnancy cautions.
Camellia sinensis, fermented with a SCOBY
Leaf
Kombucha is fermented sweet tea. What the few human trials show, and the cautions: home-brew contamination, lead from ceramic pots, alcohol, caffeine, pregnancy and weak immunity.
No fermented food matches all of these filters. Try removing one. Some topics (for example most herbs) are not fermented foods and live elsewhere on the site.
A link between a fermented food and a topic means the body needs the fermented food for that job, or that low intake is linked to it. It does not mean extra supplements help if your intake is already adequate. See each page’s evidence label.
Yogurt, kefir, aged cheese, buttermilk, skyr and lassi: milk changed by bacteria and yeasts. Lactose and milk allergy still matter.
Miso, natto, tempeh, soy sauce and other fermented soy foods. Some are very salty; natto has vitamin K.
Idli and dosa, injera and koji: grains and lentils fermented into batters and breads.
Fish sauce and fermented hot sauce: strong flavors, usually used in small amounts.
Fermented foods work alongside other nutrients. Here is what our sources link to them.
Vitamin A: The body can convert beta-carotene to vitamin A.
Vitamin A: Vitamin E and beta-carotene were tested together in the Finnish smoker trial.
Vitamin D: Vitamin D increases calcium absorption; both matter for bones, and treatment of rickets and osteomalacia includes both.
Vitamin D: NHS says vitamin D helps regulate calcium and phosphate.
Vitamin E: MedlinePlus says vitamin E helps the body use vitamin K; both affect blood clotting, which matters for people on blood thinners.
Vitamin E: Vitamin E and selenium were tested together and apart in the SELECT prostate cancer trial.
Vitamin E: Vitamin C and vitamin E were pooled with other antioxidants in the Cochrane mortality review.
Vitamin K: Vitamin D with K2 products exist; the site page does not claim an added benefit.
Vitamin B1 (thiamin): The NHS page covers B vitamins together; MedlinePlus says doctors may recommend other vitamins alongside thiamin for beriberi.
Vitamin B2: MedlinePlus says riboflavin works with the other B vitamins.
Vitamin B3 (niacin): Pellagra comes from too little niacin or tryptophan in the diet, so both matter for avoiding deficiency.
Vitamin B5: MedlinePlus covers pantothenic acid and biotin together; both are needed for growth and metabolism and for making fatty acids.
VegetablesOmega fatty acidsAntioxidantsSupplement formulasCompare supplementsNatural Remedy Safety
Aged cheese (cheddar, Parmesan, Swiss, Gouda) as a fermented food: USDA nutrients, cholesterol trials, and sodium, pregnancy, histamine, tyramine and milk allergy cautio…
Cultured buttermilk as a food: USDA nutrients per cup, what small studies found on cholesterol and blood pressure, and sodium, lactose, pregnancy and milk allergy cautio…
Skyr and quark, thick fermented milks: what small trials found on protein, fullness and muscle, composition we could verify, and lactose, pregnancy and allergy cautions.
Lassi and ayran, two yogurt drinks: what we could verify about their salt and sugar, one small gum-health trial, and lactose, pregnancy, sodium and milk allergy cautions.
Soy sauce and tamari as foods: USDA sodium values, wheat and gluten, soy allergy, MAOI medicines and histamine, plus what research does and does not show.
Fermented tofu (sufu, furu, fuyu) as a food: USDA sodium values, histamine and tyramine, homemade botulism cases, soy allergy and what research does not show.
Gochujang and doenjang, Korean fermented soy pastes: salt, histamine and Bacillus cereus findings, soy allergy, MAOI medicines and what the research really shows.
Idli and dosa are South Indian cakes made from fermented rice and black gram batter: what lab studies measured, blood sugar, gluten, rice arsenic and what is not proven.
Injera is a sour, spongy Ethiopian flatbread from fermented teff: USDA values for teff, what fermentation does to phytate and iron, gluten and celiac questions, and safe…
Koji is rice grown with the mold Aspergillus oryzae; amazake is the sweet drink made from it. What trials found on bowels and skin, sugar, mold safety and labels.
Kvass is a lightly sour, fizzy drink fermented from rye bread. What one lab study measured for alcohol, sugar and fiber, and safety points on gluten, sugar and alcohol.
Water kefir (tibicos) is a dairy-free fizzy drink fermented from sugar water and kefir grains: what a 2026 trial found, trace alcohol, sugar and who should be careful.
Fish sauce is a salty, savory liquid from fermented fish. A 2025 study of 38 bottles measured sodium and histamine; see what that means for blood pressure, allergy and M…
Fermented hot sauce is chili mash soured by lactic acid bacteria in salty brine: what lab studies measured, the sodium and heartburn questions, and what is not proven.
These fermented foods have the most human research summarized in our guides (counted from the evidence ratings on each profile). More research does not mean the fermented food works or is safe for you: open the guide to see what was found, including negative and mixed results.
Every published fermented food guide (19), with its names and what it is made of. Each name opens one guide that brings together identity, traditional use, research, safety, forms and sources.
Search by fermented food, benefit, body system, goal, symptom or lab test. Each result explains why it matches and how strong the evidence is.
Filters: kind of ferment, evidence, body system, body part, goal, root cause, habit, biomarker, condition
Pick a way to look, then pick a choice. Every list links to the full guide.
The ways each fermented food is used, from its guide: tea, tincture, capsule, powder, extract, topical or the whole fermented food.
Fermented foods whose guide documents a point to check for this concern. Being listed does not mean the fermented food is unsafe for everyone. Open the guide to read the details.
The best level of evidence in each fermented food guide for any listed benefit. A stronger label for one use says nothing about its other uses or its safety.
Fermented foods have been used for health in many cultures for centuries. A traditional use tells you what people have done, not that it works. Here every fermented food is listed under the goals, body systems and actions its guide connects it to, and each link carries the strength of the evidence behind it.
Strongest
3 fermented foods
Clinical trials support a benefit
Promising
14 fermented foods
Early or mixed human evidence
Early science
1 fermented foods
Lab or animal research only
Unknown
1 fermented foods
Too little evidence to say
Each fermented food is counted once, at the strongest level its guide documents for any use. A strong label for one use says nothing about its other uses or its safety. "Traditional use" alone is not one of these labels: where a guide only reports history, the link is rated "Too little evidence to say". Read the guide on traditional use and research evidence.
Each card shows how many fermented foods are linked to a goal and how strong the evidence is. Green means clinical trials support a benefit; grey means too little evidence. These are links the guides document, not recommendations. For the wider picture, see the Wellness Goals section.
1 strongest3 promising
Best-studied
Clinical trials support a benefit (1)
Early or mixed human evidence (3)
Goal pages: Digestive Support · Gut Health
1 strongest2 promising
Best-studied
Clinical trials support a benefit (1)
Early or mixed human evidence (2)
Goal pages: Heart Health · Blood Pressure Support · Cholesterol Balance
Early or mixed human evidence (2)
Goal pages: Blood Sugar Balance · Weight Management
Early or mixed human evidence (1)
Goal pages: Healthy Skin
Early or mixed human evidence (1)
Goal pages: Bone Health
The same links, organized the way anatomy and physiology textbooks do. "Action" describes what a fermented food is said to do (for example calming or digestive support); it names the claim, not the proof.
Clinical trials support a benefit (1)
Early or mixed human evidence (3)
Side-by-side guides for fermented foods that people confuse or choose between. They explain differences; they do not rank the fermented foods.
Each guide below looks at one concern, from sleep to skin, and separates fermented foods that were tested in people from fermented foods that are only traditional or lab-tested.
People have used fermented foods for health for many centuries. A traditional use tells you what people have done, not that it works. For what research found, see the Health Benefits and Scientific Evidence tabs.
Ayurveda, Traditional Chinese Medicine and other traditions each use natural remedies in their own systems. The fermented foods below are the ones whose guide mentions the tradition in its own text. That a tradition uses a fermented food is history, not clinical evidence. Each guide says separately what trials found.
Read more: Therapies & Traditions.
Fermented foods are active substances. Some interact with prescription medicines, some are unsafe in pregnancy or with certain conditions, and some have been linked to serious harm. This tab brings together what the individual fermented food guides document, plus the general rules. Medicine interactions have their own tab.
Have the product bottle with you when you call. Poisoning: What to Do First · Poison Help by Country · Emergency Quick Reference: Whom to Call (911, 988, Poison Help)
Each line comes from a fermented food's own guide, where it is backed by cited sources: 77 documented risks across 19 of the 19 fermented foods. A fermented food missing from a list is not proven safe: it may simply not have been studied. Open the fermented food's guide for the full wording and sources.
| Fermented food | What its guide documents |
|---|---|
| Soy Sauce & Tamari | Soy sauce and kidney disease sodium limits. NIDDK names soy sauce among high-sodium sauces and says many people with chronic kidney disease need a lower sodium limit set by … |
| Fermented food | What its guide documents |
|---|---|
| Aged Cheese | Saturated fat and heart disease. An American Heart Association advisory concluded that replacing saturated fat with unsaturated fat, especially polyunsaturated fa… |
| Fermented Hot Sauce | Hot sauce, heartburn and reflux. NIDDK lists spicy foods among foods some people find trigger or worsen acid reflux symptoms; a 2026 systematic review linked caps… |
| Fish Sauce | Fish sauce sodium and blood pressure. A 2025 study of 38 commercial fish sauces found 5,037 to 12,637 mg sodium per 100 mL. WHO recommends adults take in less than 2,0… |
| Soy Sauce & Tamari | Sodium from soy sauce and blood pressure. USDA lists about 5,500 mg of sodium per 100 g, roughly 880 to 1,000 mg in a tablespoon. Pooled trials show that cutting salt lowe… |
| Fermented food | What its guide documents |
|---|---|
| Aged Cheese | Sodium in cheese. Sodium per 100 g in the USDA data ranges from 187 mg (Swiss) to 1,175 mg (Parmesan); cheddar has 653 mg (185 mg in 1 ounce). WHO … |
| Aged Cheese | Histamine and biogenic amines in ripened cheese. A study of 125 retail ripened cheeses found tyramine in 28% (5.6 to 646 mg per kg) and histamine above 100 mg per kg in 11.2%; th… |
| Cultured Buttermilk | Sodium in cultured buttermilk. USDA lists 363 mg of sodium in 1 cup of the low-fat entry (16% DV); WHO advises adults to keep salt under 5 g (2 g sodium) a day. |
| Cultured Buttermilk | Lactose and buttermilk. NIDDK says many people with lactose intolerance tolerate about 12 g of lactose at a time. USDA lists 13.1 g of total sugars in a … |
| Fermented Hot Sauce | Sodium in fermented sauces. Salt is part of how chili ferments stay safe, and official advice says not to cut the salt in tested vegetable ferment recipes. W… |
| Fermented Hot Sauce | Home fermentation safety. Official guidance (written for vegetable ferments) says to use tested recipes, not to cut salt and notes that yeasts, molds and e… |
| Fermented Tofu (Sufu) | Sodium in fermented tofu. USDA lists 2,873 mg sodium per 100 g, about 316 mg in an 11 g block (14% of the Daily Value). |
| Fermented Tofu (Sufu) | Histamine, tyramine and other biogenic amines. Fermented bean curd had the highest total biogenic amines of the foods in a Chinese market study (average 816.8 mg per kg); a suf… |
| Fermented Tofu (Sufu) | Botulism from homemade fermented bean curd. A 2026 report traced a type B botulinum toxin poisoning to a homemade fermented bean curd product. |
| Fish Sauce | Histamine and biogenic amines in fish sauce. Some South Korean fish sauces in the 2025 study had histamine up to about 540 ppm, with several above a Taiwanese limit of 400 pp… |
| Fish Sauce | Preservatives and labeling accuracy. In the 2025 study some products had benzoates, sorbates or dehydroacetic acid above limits, and some contained triacetin, which i… |
| Gochujang & Doenjang | Salt in gochujang and doenjang. Study authors call gochujang high in salt. We found no sodium value per spoonful in a source we could read. |
| Gochujang & Doenjang | Histamine and tyramine in doenjang. In 36 doenjang products from small Korean makers, histamine ranged from 0.97 to 1,289 mg per kg and tyramine from 3.23 to 101 mg … |
| Gochujang & Doenjang | Bacillus cereus in doenjang. Found in 5 of 36 doenjang products (13.88%), 3 above the Korean standard of 4 log CFU per g. Spores were more heat resistant in s… |
| Gochujang & Doenjang | Aflatoxin in meju and doenjang. A 2025 study reported aflatoxin contamination in many of 323 meju and doenjang samples; fewer where the microbe mix was richer. |
| Idli & Dosa | Gluten and celiac disease (cross-contact). Rice and black gram are not the gluten grains (wheat, barley, rye). Gluten can still enter through other flours, shop mixes or sh… |
| Idli & Dosa | Home batter hygiene. Official home-fermentation advice says to use tested recipes and keep salt and acid as stated; it is written for vegetable fermen… |
| Injera | Gluten cross-contact and mixed-flour injera. Injera is only gluten-free if made from teff alone on clean equipment. Celiac guidance warns that naturally gluten-free grains ca… |
| Kefir | Weakened immunity and live-culture products. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immune systems, and that some products c… |
| Koji & Amazake | Koji mold species and mycotoxins. The food-use mold Aspergillus oryzae did not make aflatoxin in a rice test while wild A. flavus did. Wild A. oryzae strains can c… |
| Koji & Amazake | Occupational exposure to koji spores. One case report describes a fungal ball in the sinus of a sake brewery worker caused by A. oryzae from koji at work; she recovere… |
| Kvass | Trace alcohol in kvass. Lab-made bread kvass had about 0.34% alcohol by volume, and the authors say natural kvass stays under 0.5%. Two commercial drinks… |
| Kvass | Gluten in rye-bread kvass. Rye is a gluten grain (NIDDK lists wheat, barley, rye). Bread kvass is not gluten-free by default. |
| Kvass | Home fermentation safety. Official home-fermentation advice is written for vegetables and stresses tested recipes and clean equipment. We found no kvass-sp… |
| Lassi & Ayran | Salt in ayran. Ayran is traditionally made with salt; a lab study varied salt at 0, 0.5 and 1 g per 100 g. WHO advises adults to keep salt under… |
| Lassi & Ayran | Lactose in this dairy food. NIDDK says many people with lactose intolerance tolerate about 12 g of lactose at a time and that yogurt and hard cheeses are eas… |
| Lassi & Ayran | Weakened immunity and live-culture products. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immune systems, and that some products c… |
| Miso | Sodium in miso. USDA lists 3,728 mg sodium per 100 g, about 634 mg in a tablespoon (17 g), 28% of the Daily Value. |
| Skyr & Quark | Added sugar and sweeteners in flavored versions. Flavored skyr-type yogurts can be sweetened with sucrose or other sweeteners. WHO advises keeping free sugars under 10% of daily … |
| Skyr & Quark | Lactose in this dairy food. NIDDK says many people with lactose intolerance tolerate about 12 g of lactose at a time and that yogurt and hard cheeses are eas… |
| Skyr & Quark | Weakened immunity and live-culture products. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immune systems, and that some products c… |
| Soy Sauce & Tamari | Wheat, gluten and celiac disease. USDA lists regular soy sauce as made from soy and wheat. A lab study found gluten below the test limit in 15 soy sauces but still… |
| Soy Sauce & Tamari | Histamine and biogenic amines in fermented soy sauce. Microbes that make histamine and tyramine were isolated from soy sauce ferments. We read no typical amount per tablespoon. |
| Water Kefir (Tibicos) | Trace alcohol and sugar in water kefir. Yeast makes ethanol; in an orange juice test water kefir grains made more ethanol and acetic acid than milk kefir grains. The dri… |
| Water Kefir (Tibicos) | Live-culture safety with a weakened immune system. A review of 39 invasive Weissella confusa infections found most occurred in people with cancer, long hospital stays, devices, gut… |
| Water Kefir (Tibicos) | Home fermentation safety. Official home-fermentation advice is written for vegetables and stresses tested recipes and clean equipment; no water kefir guida… |
| Yogurt | Added sugar in flavored yogurt. Flavored yogurts can contain added sugar. WHO advises keeping free sugars under 10% of daily energy. |
| Yogurt | Weakened immunity and live-culture products. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immune systems. This statement is about … |
Some fermented foods change how a medicine works, or add to its effect. This matters most for narrow-margin medicines such as blood thinners, antidepressants, immunosuppressants, and diabetes and blood pressure medicines. Always tell your pharmacist and clinician about every fermented food you take. Ask before starting, stopping or combining anything.
Each line comes from a fermented food's own guide and its cited sources. A fermented food missing from a list is not proven free of interactions: it may simply not have been studied. Open the fermented food's guide for the full wording.
| Fermented food | What its guide documents |
|---|---|
| Aged Cheese | Tyramine and MAOI antidepressants. MedlinePlus says eating high-tyramine foods during treatment with an MAOI such as tranylcypromine can cause a serious reaction an… |
| Fermented Tofu (Sufu) | MAOI antidepressants and tyramine. An older lab study found stored tofu reached clinically significant tyramine after a week and advised people on MAOIs to avoid so… |
| Fish Sauce | Fish sauce and MAOI antidepressants. A review says tyramine-rich foods can trigger hypertensive crisis in people taking MAOIs, and StatPearls names aged, fermented, c… |
| Gochujang & Doenjang | MAOI antidepressants and fermented soy pastes. Reviews say fermented foods and Asian fermented soy foods can carry amines above toxic levels, and medicines raise the risk. No p… |
| Miso | MAOI antidepressants and tyramine. Reviews say fermented foods and Asian fermented soy foods can contain tyramine and histamine; medicines raise the risk. No miso-s… |
| Natto | Vitamin K and warfarin. A hospital patient page lists natto among vitamin K-rich foods for people on warfarin and advises keeping intake steady; MedlineP… |
| Natto | MAOI antidepressants and histamine. Reviews say fermented foods and Asian fermented soy foods can carry tyramine and histamine. No natto-specific amount was read. |
| Soy Sauce & Tamari | MAOI antidepressants and tyramine. A 1999 lab study found high tyramine in one soy sauce and advised avoiding soy sauce on MAOIs; product values differ. |
For most fermented foods, good human evidence is limited. Every outcome in our fermented food guides is rated for how strong the evidence is, and the rating is shown next to it. Across the 19 guides, 16 fermented foods have no outcome rated "clinical trials support a benefit".
These are the outcomes our guides rate "clinical trials support a benefit", each with the sources the guide cites. Even here, the effect is usually for one preparation, one group of people and one outcome.
| Fermented food | Outcome | What the guide says | Sources |
|---|---|---|---|
| Aged Cheese | Cheese and blood cholesterol compared with butter | A pooled analysis of 5 randomized trials found hard cheese (about 145 g a day) lowered LDL cholesterol by about 6.5% and HDL by about 3.9% compared with butter, with no change in triglycerides. Compared with tofu or fat-modified … | PubMed (Nutr Rev): Effect of cheese consumption on blood lipids: systematic review and meta-analysis of RCTs (de Goede et al.) (2015) |
| Cultured Buttermilk | Milk fat globule membrane ingredients and LDL cholesterol | A meta-analysis of 13 randomized trials in disease-free adults found MFGM and milk polar lipid ingredients (19.8 to 5,000 mg a day for 2 to 16 weeks) lowered LDL cholesterol by about 0.12 mmol/L with moderate certainty; HDL, trig… | PubMed (Adv Nutr): Milk fat globule membrane and polar lipids and cardiometabolic markers: systematic review and meta-analysis of RCTs (Borkar et al.) (2026) |
| Yogurt | Yogurt and lactose digestion | A systematic review of 108 studies concluded yogurt eating is causally linked to better lactose digestion and tolerance. In a small trial of 15 adults with lactose maldigestion, plain yogurt produced much less breath hydrogen tha… | PubMed (Nutr Rev): Yogurt, cultured fermented milk, and health: a systematic review (Savaiano, Hutkins) (2021)PubMed (J Am Diet Assoc): Kefir improves lactose digestion and tolerance in adults with lactose maldigestion (Hertzler, Clancy) (2003)NIDDK: Eating, diet, and nutrition for lactose intolerance (2018) |
How many outcomes each guide rates in each evidence group. Open a guide for the individual outcomes, what was found (including negative results) and the sources.
| Fermented food | Trials support | Early / mixed | Lab / animal | Not enough | Risks |
|---|---|---|---|---|---|
| Aged Cheese | 1 | 2 | 0 | 0 | 6 |
| Cultured Buttermilk | 1 | 2 | 0 | 0 | 4 |
| Fermented Hot Sauce | 0 | 1 | 2 | 1 | 4 |
| Fermented Tofu (Sufu) | 0 | 1 | 0 | 2 | 5 |
| Fish Sauce | 0 | 0 | 0 | 1 | 5 |
| Gochujang & Doenjang | 0 | 1 | 1 | 2 | 6 |
| Idli & Dosa | 0 | 1 | 2 | 1 | 4 |
| Injera | 0 | 1 | 1 | 2 | 3 |
| Kefir | 0 | 4 | 0 | 2 | 3 |
| Koji & Amazake | 0 | 2 | 1 | 2 | 3 |
| Kvass | 0 | 0 | 3 | 1 | 4 |
| Lassi & Ayran | 0 | 1 | 0 | 4 | 5 |
| Miso | 0 | 3 | 0 | 2 | 3 |
| Natto | 0 | 4 | 0 | 1 | 3 |
| Skyr & Quark | 0 | 4 | 1 | 0 | 5 |
| Soy Sauce & Tamari | 0 | 1 | 1 | 1 | 6 |
| Tempeh | 0 | 1 | 2 | 3 | 1 |
| Water Kefir (Tibicos) | 0 | 2 | 1 | 1 | 3 |
| Yogurt | 1 | 3 | 0 | 1 | 4 |
The guides cite 134 distinct sources. These are the ones cited most often, and the main places to check any fermented food claim yourself.
The same material can be sold as a powder, capsule, liquid or concentrated extract, and these are not interchangeable. A study of one preparation does not tell you what another does. This tab shows which forms each guide describes, and how to judge product quality.
Different parts can contain different compounds, so the part named on the label matters.
For each kind of preparation, the fermented foods whose guides describe it. The guides say which form was actually studied. Detailed preparation instructions are in Herbal Teas & Extracts, so they are not repeated here.
Read:
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A whole fermented food (fresh, dried or powdered) contains everything in the raw material, in amounts that vary. A standardized extract is made to contain a stated amount of one or more marker compounds, which makes batches more consistent but is not the same as the whole fermented food.
An extraction ratio such as 4:1 says how much raw material was used per unit of extract. It does not by itself say how much active compound a capsule holds or whether the product works. A marker compound is something measured for quality control; it is not always the compound that causes any effect.
Amounts and duration. We do not give universal dose recommendations. Where a source reports the amount and length of use tested for a named preparation, the fermented food's guide gives it in that context; an amount studied in one product does not carry over to another, or to food-level use.
Absorption. Some active constituents are poorly absorbed, which is why concentrated or specially formulated products exist (curcumin is the best-known case). Better absorption can also raise the risk of side effects.
A good label names the species by its scientific name, says which part is used, and states the amount and form. Third-party testing can check identity, strength and contamination, but a seal is not a guarantee of safety or benefit.
Forms & preparations: the full guide · Herbal Teas & Extracts
No. An expert panel (ISAPP) says fermented foods are defined by how they are made, and some have no living microbes when eaten: baked sourdough, pasteurized fermented vegetables, vinegar, soy sauce, wine and most beers. [1] Yogurt, kefir, most cheeses, miso, natto and tempeh do contain live microbes. [1] The panel also says a food should be called "probiotic" only when a well-defined live strain has a shown health benefit. [1] See live cultures on labels.
It depends on the food. The NHS says to avoid unpasteurized milk, cream, yogurt and butter in pregnancy because of listeria, and says soft white-rind and soft blue cheeses should be thoroughly cooked. [4] That NHS page does not mention kefir or probiotic drinks, so check the label for pasteurization and ask your midwife or doctor. [4] See foods in pregnancy.
The NHS lists histamine as something a person can be intolerant to, found in foods and drinks such as wine and cheese. [5] Food intolerance is not an allergic reaction, and the NHS advises seeing a GP rather than cutting foods out on your own. [5] NCCIH adds that tyramine-rich soy foods such as tofu and soy sauce can interact dangerously with MAOI antidepressants. [6]
They are different products. NCCIH says probiotics are live microbes found in yogurt and other fermented foods as well as in supplements, and the risk of harm is higher for people with weakened immune systems. [2] The NHS says the evidence for probiotics is limited and uncertain, with some evidence for irritable bowel syndrome, and that shop products may differ from the strains tested in trials. [3] See fermented foods versus probiotic supplements.
Some can be, so check the Nutrition Facts label. The FDA says adults should have less than 2,300 mg of sodium a day, that more than 70 percent of it comes from packaged and prepared foods, and that 5 percent of the Daily Value or less per serving is low and 20 percent or more is high. [7] For example, see soy sauce and tamari. Soy and wheat are major allergens, so check labels if you are allergic. [8]
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Content last updated . The tabs from Health Benefits onward are compiled automatically from the evidence ratings and sources in each fermented food's guide (last data update November 13, 2026). This section has not been medically reviewed.
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