Fermented Foods Benefits and Sauerkraut Labels

Fermented foods are a kitchen topic. They are not a treatment for a gut condition or a skin condition. This page uses the ISAPP consensus definition, one diet study in healthy adults, and label advice from clinic and university pages. It does not rank brands, and it does not report anyone’s meals.

Ferments also show up in skincare formulas. Glow Coded’s galactomyces guide covers that ingredient on skin. It is a different question from food.

What fermented foods are

An ISAPP consensus panel defines fermented foods and drinks as “foods made through desired microbial growth and enzymatic conversions of food components” (Marco et al., Nature Reviews Gastroenterology & Hepatology, 2021). The microbes have to do the work. Adding vinegar, or letting a food’s own enzymes act, is not enough. ISAPP’s explainer says foods made only by pickling in vinegar should not be called fermented.

The same definition does not require live microbes in the finished food, and it does not require a health benefit. Bread is fermented and then baked, which kills the microbes. Many beers and wines are filtered or otherwise cleared of live microbes. Those products are still fermented foods. They are not the same thing as a jar of raw sauerkraut.

ISAPP also separates fermented foods from probiotics. A probiotic is a live microbe, identified to the strain, given in an amount that has been shown to confer a health benefit. Most fermented foods contain a mix of microbes that changes by batch. The panel says manufacturers can say “contains live and active cultures” when live microbes are still present at levels expected for that food. That phrase is not a probiotic claim. A supplement is a different product. The probiotics for women guide stays on that side of the line, and it is not a treatment page either.

What studies have measured

The clearest recent diet trial is Wastyk and colleagues, published in Cell in 2021 (PMID 34256014). It was a 17-week randomized study in healthy adults, with 18 people in each arm. One arm ate a high-fiber diet. The other ate a high fermented-food diet. The fermented foods included yogurt, kefir, fermented cottage cheese, kombucha, vegetable brine drinks, and fermented vegetables such as kimchi.

The primary outcome, a cytokine response score, did not change in either arm. What did change in the fermented-food arm was microbiome diversity, which rose over the study and stayed higher in a later choice period, and a set of inflammatory markers. The authors report that 19 of 93 measured inflammatory proteins in blood fell, including IL-6. That is a finding in healthy adults on an assigned high intake. It is not evidence that fermented foods treat inflammatory disease, irritable bowel syndrome, or any skin condition. The paper does not set a serving size for the general public. Copying the study diet is not the point of this page.

Cleveland Clinic’s fermented-foods page suggests starting with one or two fermented foods rather than overhauling meals, and checking labels for added sodium and sugar. That is practical diet advice from a clinic page. It is not a dose.

Skin, kept separate

Researchers use “gut-skin axis” for associations between gut findings and skin findings. Those papers are summarized on the gut-skin connection explainer. They do not show that eating kimchi, sauerkraut, or any other ferment changes acne, eczema, or rosacea. This page does not repeat those associations as a food result.

A short starter list

ISAPP’s paper groups some foods as often still containing live microbes when they are not heat-treated: yogurt, kefir, most cheeses, miso, natto, non-heated fermented vegetables, and most kombuchas. Heat-treated or pasteurized versions of those foods may not. The list below is a map of foods, not a benefits ranking.

Yogurt and kefir. Often sold with a “live and active cultures” line. Sweetened cups can carry a lot of added sugar. The American Medical Association’s patient brief flags that.
Kimchi. A salted, fermented vegetable, usually napa cabbage with garlic, ginger, and chili. Heat-treated jars may not keep live cultures. A home batch is covered in how to make fermented kimchi.
Sauerkraut. Salted cabbage. The label checks are in the next section. A home batch is in how to make sauerkraut.
Miso and natto. Soy ferments. Miso is often used in hot soup. Boiling can matter for live microbes, which the ISAPP definition already treats as optional.
Kombucha. A fermented tea. Many bottles are high in sugar, and some are pasteurized. The Stanford page below separates pasteurized kombucha from kombucha that still has live microbes.
Beet kvass. A salted beet drink. The method on this site is fermented beetroot kvass. The word “probiotic” in that older title is broader than the ISAPP definition. The drink is a ferment, not a proven probiotic.

A longer catalogue of ferments is not on this site yet. Bone broth is a separate food, not a ferment, so it is not in this list.

Best sauerkraut for gut health: the label

There is no brand ranking here. “Best,” for a live-culture jar, is a label question. Three checks show up across clinic and university pages.

Raw or unpasteurized. Cleveland Clinic says pasteurization heats sauerkraut and kills the live cultures, and that the word pasteurized is often missing from the label. Stanford’s how to recognize fermented foods puts unpasteurized sauerkraut in the group that still contains live fermenting microbes and their byproducts. The same page says those microbes are not automatically probiotics, because the mix is not identified to the strain. Words that sometimes appear on the jar include raw, wild, naturally fermented, or live and active cultures. A missing phrase is a reason to read the rest of the label, not a reason to expect a health result.

Refrigerated. Cleveland Clinic says the practical cue is the refrigerator case, and that shelf-stable sauerkraut is generally pasteurized. The AMA brief says the room-temperature sauerkraut aisle does not hold live and active cultures, and that some foods are fermented and then pasteurized. Refrigerated does not guarantee live cultures. It is the place to start looking.

A short ingredient list. Cleveland Clinic says a traditional jar lists cabbage and salt, and that garlic or a seed such as fennel can be there for flavor. A long list of unfamiliar additives is a reason to pick another jar. Stanford notes that a vinegar ingredient often means the food was acidified rather than fermented. ISAPP makes the same distinction: vinegar pickling alone is not fermentation. Sauerkraut is also salty. The AMA brief says to check sodium on fermented vegetables.

None of those checks is evidence that sauerkraut treats bloating, “gut health” as a diagnosis, or a skin condition. People who have been told to limit salt, or who already avoid ferments for a reason a clinician gave them, should follow that advice rather than a label guide.

How to start

The three ferments with a method page on this site are kimchi, sauerkraut, and beet kvass. Cleveland Clinic’s general fermented-foods page says to start with a small amount of one or two foods. That is a caution about changing a diet quickly. It is not a serving target, and it is not a promise about comfort or skin.

Store jars and home jars follow the same label idea: salt and the vegetable, time, and cold storage once the ferment tastes right. Home fermentation can spoil if the method is off. The how-to pages are the place for the steps. This page does not add a recipe.

Frequently asked questions

What are the benefits of fermented foods?

ISAPP’s definition describes how the food is made. It does not include a health benefit. In healthy adults, the 2021 Cell study found higher microbiome diversity and lower levels of some inflammatory blood markers on a high fermented-food diet, while the primary immune score did not change. That is one small study. It does not show that fermented foods treat a gut or skin condition.

What is the best sauerkraut for gut health?

No brand is ranked here. For live cultures, Cleveland Clinic and Stanford point to raw or unpasteurized sauerkraut, kept refrigerated, with a short ingredient list such as cabbage and salt. Shelf-stable jars are usually pasteurized, and vinegar-pickled cabbage is a different product. Those label checks are not a treatment.

Are fermented foods the same as probiotics?

No. ISAPP says a probiotic must be a defined live strain, given in an amount that has been shown to confer a health benefit. A fermented food can contain a changing mix of live microbes, or none, if it was heated or filtered. “Live and active cultures” on a label is not the same claim as “probiotic.”

Do all fermented foods contain live cultures?

No. ISAPP includes baked bread, and many beers and wines, as fermented foods even though the live microbes are gone by the time you eat or drink them. Pasteurized sauerkraut, kimchi, and kombucha can be fermented foods without live cultures. The refrigerator case and the words raw, unpasteurized, or live and active cultures are the usual clues.

Can fermented foods change a skin condition?

Studies have not shown that. Associations between gut findings and skin findings are covered on the gut-skin connection page. They are not evidence that a food changes acne, eczema, or rosacea.

Where do kimchi, sauerkraut, and kvass fit?

They are salted vegetable ferments. Kimchi and sauerkraut are in the starter list above, with home methods linked. Beet kvass has its own method page. Whether a given jar still has live cultures depends on heat treatment, which is a label question, not a guarantee of a health result.

Sources

Marco ML et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nature Reviews Gastroenterology & Hepatology. 2021. https://www.nature.com/articles/s41575-020-00390-5
ISAPP. Creating a scientific definition of fermented foods. https://isappscience.org/creating-a-scientific-definition-of-fermented-foods/
Wastyk HC et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021. PMID 34256014. https://pubmed.ncbi.nlm.nih.gov/34256014/
Cleveland Clinic. Sauerkraut benefits, including pasteurization and the ingredient list. https://health.clevelandclinic.org/sauerkraut-benefits
Cleveland Clinic. Fermented foods. https://health.clevelandclinic.org/fermented-foods-benefits
Stanford Medicine. How to recognize fermented foods. https://med.stanford.edu/nutrition/education/Resources/Fermenting-the-Facts/How-to-Recognize-Fermented-Foods.html
American Medical Association. From kimchi to kefir. https://www.ama-assn.org/public-health/prevention-wellness/kimchi-kefir-what-tell-patients-about-fermented-foods