Preserving your Health with Fermented Foods
Young Ju, Ph.D.
Fermented foods have been essential parts of human diets for thousands of years. This article provides an overview of fermented foods, summarizes the latest research findings on their potential health benefits, and offers practical guidance for incorporating fermented foods into your diet.
Food Fermentation
Almost every human culture has developed traditional fermented foods using locally available ingredients and indigenous techniques. Food fermentation is an ancient food preservation method that also improves food flavor, texture, and nutritional value.
Fermented foods are produced through the controlled growth of microorganisms and the enzymatic conversion of food components (1). During fermentation, microorganisms such as bacteria, yeasts, and fungi break down food components, producing organic acids, alcohols, vitamins, and other byproducts. These processes can create new flavors and textures and may improve the digestibility and bioavailability of certain nutrients. Some fermented foods, such as sauerkraut and kimchi, may use naturally occurring microorganisms, whereas others (2), such as yogurt and kefir, typically use specific starter cultures to help control fermentation. Although fermentation involves microorganisms, not all fermented foods contain probiotics. Probiotics are live microorganisms that can benefit your health when consumed in adequate amounts.
Types of Fermented Foods (3, 4)
Fermented foods can be categorized according to whether they contain live microorganisms at the time of consumption and whether probiotics have been added.
Fermented foods containing live microorganisms (not heat-treated) include sauerkraut, kimchi, kefir, sour cream, most cheeses, yogurt, miso, and natto.
Fermented foods not containing live microorganisms (heat-treated) undergo pasteurization or other heat treatments that eliminate microorganisms. Microbial activity during fermentation can produce byproducts that may have health effects independent of live microorganisms. This includes most beer, wine, sourdough, chocolate, some fermented sauces and condiments.
Fermented foods (heat-treated) with added probiotics include some yogurt, some kefir, some cheese, buttermilk, and kombucha.
Some foods including chemically leavened bread made with baking powder or baking soda, vegetables pickled in vinegar, and some salted or cured processed meats (deli ham, hot dogs, bacon) and fish (salted cod), may appear similar to fermented foods, but they are primarily produced through other processes. However, some of these products may also undergo fermentation as part of their production.
Sources of Fermented Foods (3, 4)
Fermented foods are produced from a wide variety of plant and animal foods and can be categorized as follows:
Cereals and grains: sourdough, loaves, cereal beverages, etc.
Meat and seafood: prosciutto, sausage, ham, jerky, smoked fish, and fish sauce, etc.
Dairy: yogurt, kefir, cheese, cultured sour cream and buttermilk, etc.
Legumes and soybeans: miso, soy sauce, tempeh, and natto, etc.
Vegetables and fruits: sauerkraut, kimchi, fermented olives, pickles, and vinegar, etc.
Beverages and other: kombucha, rum, wine, beer, cocoa beans, and coffee beans, etc.
Potential Health Benefits
Current research suggests that fermented foods may have several potential health benefits. While most research heavily focuses on dairy products, note that fermented foods differ substantially in their nutritional composition, microbial communities, fermentation methods, and potential health effects. Therefore, health benefits from one fermented food should not automatically be generalized to all fermented foods.
Fermented foods may influence the composition and activity of microorganisms in the gut (5). Related to athletes, it has been observed that exercise and microbial community influence each other. Although no clear recommendations are established currently, recent studies showed that fermented foods like kefir (6) and sauerkraut (7) improved microbial community in athletes.
Fermented food consumption was associated with gastrointestinal health benefits including improvements in bowel-movement frequency, stool consistency, and digestive health (8).
Fermented milk consumption was associated with lower cardiovascular risk (9).
Higher fermented food (including fermented milk, cheese, and chocolate) consumption was associated with lower all-cause and cardiovascular mortality (10).
Yogurt consumption was associated with lower risk of type 2 diabetes and metabolic syndrome (9, 11, 12).
Higher cheese intake was associated with lower colorectal cancer risk, and higher yogurt intake was associated with lower rectal cancer risk (13).
Choosing Fermented Foods (14)
When shopping for fermented foods, check the following:
Storage: Most fermented foods are refrigerated to help maintain live microorganisms.
Labeling: Look for terms like fermented, cultured, or live active cultures. If a product contains added probiotics, the specific microorganism or strain and the amount would be provided.
Microbial strains: Fermented dairy products typically list live bacterial species, while other products may not list them due to complex microbial communities.
Ingredients: Products containing vinegar are acidified for stability and often are not truly fermented.
Fermented foods can be nutritious, but some products may also contain substantial amounts of salt, added sugar, saturated fat, and alcohol.
Containers: Buying acidic products in glass containers as organic acids produced during fermentation can react with certain plastics over time.
How Much is Enough?
Currently, there are no established guidelines for daily intake levels of fermented foods. Researchers are still investigating whether health benefits primarily depend on the amount of fermented food consumed, the number and type of live microorganisms, specific microbial strains, fermentation byproducts, or a combination of these factors. A practical approach could be to introduce fermented foods gradually and include a variety of products as tolerated.
Examples of reasonable portions (15) include:
Fermented vegetables (sauerkraut, kimchi, pickles): ~ ¼ cup
Yogurt, cottage cheese, or kefir: ~6 ounces
Kombucha, or water kefir: ~6 ounces
Fermented salsa: ~2 tablespoons
Miso: ~1 tablespoon
Fermented vinegar: ~1 tablespoon
Who Should Be Careful With Fermented Foods? (16)
In general, taking fermented foods is safe for most people when properly produced and stored. However, some individuals may initially experience mild and temporary symptoms including gas, bloating, abdominal discomfort, and changes in bowel movements. Major risks associated with fermented foods were usually due to contaminated raw materials, inadequate processing, poor hygiene, or other process failures rather than fermentation itself.
People with food allergies or intolerances: milk, soybean, wheat, or fish, who are sensitive to biogenic amines (a type of fermentation byproduct) or people who need to limit sodium and/or sugar should be cautious about intake. Many commercial options can contain high levels of sodium or added sugar.
Conclusion
Fermentation can improve preservation, flavor, and texture and can alter nutrients in foods. Fermented foods may contain a complex and variable mixture of microorganisms and fermentation byproducts. Current research suggests that certain fermented foods may provide health benefits. However, health effects vary substantially among fermented foods. The strongest evidence is for benefits to gastrointestinal health.
Try to choose fermented food products that fit your overall dietary needs. As always, it is important to read the labels and weigh the potential risks against expected benefits.
Dr. Young Ju is a Ph.D and Associate Professor of Human Nutrition, Foods, and Exercise at Virginia Tech.
References
Dimidi et al. “Fermented foods: Definitions and characteristics, impact on the gut microbiota and effects on gastrointestinal health and disease.” Nutrients 2019. 11(8):1806.
Canadian Digestive Health “Probiotics vs. Fermented foods” https://cdhf.ca/en/probiotics-vs-fermented-foods/
Stanford Medicine “Fermenting the Facts: A science-based guide to fermented foods” https://med.stanford.edu/nutrition/education/Resources/Fermenting-the-Facts.html
Tamang et al. “Characterization of fermented foods: Bone health” Frontiers in Nutrition 2025, 12:1648775.
Leeuwendaal et al. “Fermented foods, health and the gut microbiome” Nutrients 2002, 14(7):1527.
Ones et al. “Effects of kefir consumption on gut microbiota and athletic performance in professional female soccer players: a randomized controlled trial” Nutrients 2025, 17(3):512.
Zonjic et al. “The short- and long-term effects of a short course of sauerkraut supplementation on the gut microbiota of active athletes: A pilot follow-up study” Nutrients 2025, 17(5):929.
Sampsell et al. “Current research in fermented food: Bridging tradition and science” Advances in Nutrition 2025, 16(12):100554.
Li et al. “Fermented foods and cardiometabolic health: Definitions, current evidence, and future perspectives” Frontiers in Nutrition 2022, 9:976020.
Matalas et al. “Fermented foods consumption, all-cause, and cause-specific mortality: a meta-analysis of prospective cohort studies” Frontiers in Nutrition 2026, 13:1714437.
Schropp et al. “Fermented foods and inflammation: a crossover intervention trial with fresh and pasteurized sauerkraut” European Journal of Clinical Nutrition 2026, doi: 10.1038/s41430-026-01776-5.
Zhang et al. “Fermented foods and metabolic outcomes in diabetes and prediabetes: A systematic review and meta-analysis of randomized controlled trials” Critical Reviews in Food Science and Nutrition 2024, 64(26):9514.
Liang et al. “Fermented dairy food intake and risk of colorectal cancer: A systematic review and meta-analysis” Frontiers in Oncology 2022, 12:812679.
Stanford Medicine “How to recognize fermented foods” https://med.stanford.edu/nutrition/education/Resources/Fermenting-the-Facts/How-to-Recognize-Fermented-Foods.html
Marco et al. “A classification system for defining and estimating dietary intake of live microbes in US adults and children” The Journal of Nutrition 2022, 152(7):1729.
Assunção R, Angelovski L, Ciesarová Z, et al. Are fermented foods safe for human health? A systematic analysis of the literature. Frontiers in Nutrition. 2026;13:1905861.
People with any health problems should talk to their healthcare providers. This information is provided for your reference, and you use at your own risk; you should rely on your medical professional for medical advice.
