Probiotic foods are fermented foods that still contain live bacteria or yeasts when you eat them, such as yogurt and kefir with live cultures, unpasteurized sauerkraut and kimchi, miso, tempeh, some aged cheeses and kombucha. The US National Center for Complementary and Integrative Health describes probiotics as live microorganisms intended to have health benefits, found in yogurt and other fermented foods as well as supplements. Not every fermented food contains live microbes: sourdough bread, most beer and wine, and shelf-stable pickles and sauerkraut have been baked, filtered or heat-treated.
Probiotic, fermented or prebiotic?
These terms get mixed up:
| Term | What it means | Examples |
|---|---|---|
| Probiotic | Live microorganisms that may benefit health | Live-culture yogurt, kefir, many supplements |
| Fermented food | Food made using microbes; may or may not still contain live ones | Yogurt, sauerkraut, kimchi, miso, sourdough, cheese |
| Prebiotic | Food components, mainly certain fibers, that feed helpful gut bacteria | Onions, garlic, leeks, oats, bananas, beans, asparagus |
The NCCIH explains that prebiotics are nondigestible food components that selectively stimulate the growth or activity of helpful microorganisms, and that products combining both are called synbiotics.
Probiotic foods to try
Yogurt
The most familiar probiotic food. Look for “live” or “active cultures” on the label, because some yogurts are heat-treated after fermentation. Choose plain versions to avoid added sugar. Our guide to whether yogurt is good for you compares types.
Kefir
A fermented milk drink that usually contains a wider mix of bacteria and yeasts than yogurt. It’s tangy and slightly fizzy. Plain kefir works in smoothies, overnight oats and dressings. Water kefir is a dairy-free version, but often contains added sugar.
Sauerkraut and kimchi
Fermented cabbage, and in kimchi’s case other vegetables with chili, garlic and ginger. Only raw, refrigerated versions labeled “unpasteurized” or “live” contain live bacteria. Jars from the shelf have usually been heat-treated. Both are salty, so a small spoonful as a side is plenty.
Miso and tempeh
Miso is a fermented soybean paste used in soups, dressings and marinades. Adding it at the end of cooking, rather than boiling it, helps keep more live microbes. Tempeh is fermented soybean cake, high in protein, but it’s always cooked, so it’s valued more as a fermented food than as a source of live bacteria.
Aged cheeses
Some traditional cheeses, such as aged cheddar, Gouda and some soft cheeses, contain live bacteria. Cheese is also high in salt and saturated fat, so keep portions moderate.
Kombucha
A fermented sweetened tea. Many brands contain live microbes, but sugar content varies, and homemade kombucha needs careful hygiene to avoid contamination. It contains small amounts of alcohol from fermentation.
What the evidence shows
Evidence in this area is growing, but it’s still early:
- In a 2021 Stanford study, 36 healthy adults followed either a high-fiber or a high-fermented-food diet for 17 weeks. The fermented food group, who gradually increased foods such as yogurt, kefir, kimchi and kombucha, had a steady rise in the diversity of their gut bacteria and lower levels of several inflammatory markers. The high-fiber diet didn’t increase diversity over that time. It was a small study, so the results need confirming.
- Harvard’s Nutrition Source notes links between daily yogurt and lower risk of type 2 diabetes in long-term studies.
- The NCCIH says probiotics have shown promise for some uses, such as preventing diarrhea linked to antibiotics, but that effects depend on the specific strain and that many claims haven’t been proven.
A practical takeaway: eating a variety of fermented foods, alongside plenty of fiber from plants, is a reasonable way to support gut health, but probiotic foods aren’t a treatment for medical conditions.
Probiotic foods vs supplements
Supplements contain specific strains in measured doses, and some have evidence for particular uses. Food sources give you a mix of microbes plus nutrients such as protein, calcium and fiber. The NCCIH notes that supplements may make claims about how they affect the body without FDA approval, but can’t claim to treat or prevent diseases without the FDA’s consent. Ask your doctor or pharmacist before taking a probiotic supplement for a specific health problem.
Who should be careful
Probiotic foods are safe for most people. The NCCIH notes that serious infections have been reported in premature infants given probiotic supplements, and more caution is needed for people who are seriously ill or have weakened immune systems. If that applies to you, ask your medical team before taking probiotic supplements.
Other points:
- Pregnancy: choose pasteurized dairy products, such as most supermarket yogurts and kefirs, and avoid unpasteurized milk drinks and some soft cheeses. Our guide to foods to avoid during pregnancy explains which.
- Salt: kimchi, sauerkraut and miso are high in salt. Small portions are best if you’re watching your blood pressure.
- Wind and bloating: can happen at first. Start with small amounts.
Feed your gut bacteria too
Prebiotic fiber feeds the bacteria already in your gut. Good sources include onions, garlic, leeks, asparagus, bananas, oats, barley, beans and lentils. Our high-fiber foods list has more ideas.
Easy ways to eat more fermented foods
- Plain yogurt or kefir with fruit for breakfast
- A spoonful of live sauerkraut or kimchi alongside eggs, salads or rice bowls
- Miso stirred into soup or salad dressings at the end
- Tempeh in stir-fries or sandwiches
Common questions
Does cooking kill probiotics?
Yes. Heat kills most live bacteria, which is why miso is added at the end and baked or pasteurized foods don’t contain them.
How much probiotic food should I eat?
There’s no official amount. A serving or two a day, such as a pot of yogurt and a spoonful of sauerkraut, is a reasonable start.
Is sourdough bread probiotic?
No. Sourdough is made by fermentation, but baking kills the microbes.
Are probiotic yogurt drinks worth buying?
Some contain specific strains that have been tested for particular uses, but many are also high in sugar. A plain live yogurt or kefir is usually a cheaper, lower-sugar way to get live cultures.
Can children eat fermented foods?
Yes. Plain yogurt and kefir are good choices for children. Salty foods such as kimchi, sauerkraut and miso are best in small amounts.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
