The Top 8 Fermented Foods to Eat for Gut Health

Eating fermented foods can help maintain a healthy gut microbiome. Having a diverse array of bacteria in your intestinal tract not only supports regular digestion, but it also has been linked to everything from better mood and blood sugar control to lower risks of allergies and improved immune function. 

Fermented foods include those that are either made with or contain live, active bacteria. Fermentation occurs when bacteria or yeast (which may occur naturally or be added during processing) break down the natural sugars in foods. This breakdown yields new compounds like alcohol, carbon dioxide, and lactic acid. Fermentation influences the flavor, texture, and nutritional profile of foods and beverages.

Research suggests that regularly including fermented foods in your diet can help diversify the healthy bacteria in your gut. Here are the best fermented foods you should add to your diet.

1. Sauerkraut

Sauerkraut has been consumed across cultures for centuries. A staple food in both European and Asian cuisine, sauerkraut is a wonderful source of live, active cultures–as long as it hasn’t been pasteurized.

Any sauerkraut that has been pasteurized does not contain healthy microbes, as heating kills the beneficial bacteria in the kraut. Sauerkrauts with live, active cultures are typically refrigerated, not shelf stable. 

Sauerkraut contains vitamins C and K and boasts potent anti-inflammatory properties. Cruciferous vegetables like cabbage are also wonderful sources of sulforaphane, a compound that appears to have powerful anti-cancer properties.

While sauerkraut may boost gut health in some people, not everyone tolerates it well. Some people diagnosed with irritable bowel syndrome (IBS) may find that fermented foods like sauerkraut actually worsen their IBS symptoms. This may be due to the high levels of fermentable (or gas-producing) carbohydrates, like mannitol, in sauerkrauts made from white cabbage.

However, tolerance is highly individual. Start by adding a small amount of sauerkraut–such as 1 tablespoon–to a meal and see how you feel. 

2. Kombucha

Kombucha is a carbonated, fermented beverage that’s made by combining tea, sugar, and a ‘symbiotic culture of bacteria and yeast,’ often referred to as ‘SCOBY.’ When combined, the SCOBY converts sugars into alcohol and then acids that contribute to kombucha’s signature tangy flavor.

Since tea is a powerful source of antioxidants, kombucha likely contains beneficial plant nutrients called phytochemicals. Yet despite its popularity, studies confirming kombucha’s gut health benefits remain limited.

Choosing kombucha over alternatives like soda is surely a helpful swap, but know that kombucha contains sugar as well. If you’re watching your added sugar intake, consider mixing kombucha with seltzer for less sweetness. 

Finally, kombucha contains trace amounts of alcohol, which is naturally created by the fermentation process. The alcohol by volume (ABV) content can be as low as 0.5%, but it may still matter to you if you avoid alcohol for personal, medical, or religious reasons.

3. Kimchi

A staple of Korean cuisine, kimchi is another form of fermented cabbage. This side dish is typically made from more ingredients than sauerkraut, though. Common combinations include napa cabbage, radish, salt, water, fish or soy sauce, garlic, onions, ginger, and red pepper.

Evidence supporting the benefits of kimchi is abundant. The fermented food is rich in beneficial bacterial species like Lactobacilli, dietary fiber, and other compounds with antioxidant, cholesterol-lowering, and immune-enhancing properties. Researchers believe this unique combination may even make kimchi anti-carcinogenic, or cancer-fighting.

4. Tempeh

Similar to tofu, tempeh is a plant-based protein made from fermented soybeans. Because tempeh is typically pasteurized and cooked prior to consumption, it’s not likely to retain active cultures. Still, tempeh may be a good source of ‘paraprobiotics,’ which are defined as inactive microbes that still deliver good health benefits.

Tempeh is rich in heart healthy plant-based protein and dietary fiber. Just 1 cup of tempeh can provide an impressive 34 grams (g) of protein and 6 g of fiber.

5. Kefir

Kefir is a fermented dairy product that’s made by combining kefir ‘grains’ with milk from cows, goats, sheep, or even buffalos. Kefir ‘grains’ are not actually grains, but a starter culture instead made of bacteria and yeast that serves as a fermenting agent.

Cultured dairy products like kefir and yogurt have the strongest evidence behind their probiotic properties. Kefir has been shown to bolster microbial diversity in the gut and help lower inflammation in the body. 

The drinkable yogurt may improve cardiovascular health as well. In a randomized control trial, study participants who consumed a bottle of kefir daily for 12 weeks had significant increases in ApoA1, the primary protein found in healthy HDL cholesterol, when compared to participants who were given regular milk. Interestingly, both groups experienced similar reductions in inflammatory markers in the blood, regardless of whether they consumed kefir or regular milk daily.

Kefir is packed with protein, potassium, and calcium, and is extremely low in lactose. Even those with lactose intolerance may tolerate kefir.

While kefir’s consistency is looser than traditional yogurt, you can enjoy it just like you would normal yogurt. Other easy ways to enjoy kefir include adding it to smoothies or using it to marinate proteins like chicken kabobs. 

6. Yogurt

Yogurts containing live, active cultures are another wonderful source of gut-friendly probiotics. Unlike other fermented foods, the bacteria in yogurt have been proven to survive transit through the GI tract. This is important because bacteria need to reach the intestines intact in order to influence gut health.

Yogurt is also a source of high-quality protein, vitamin B12, calcium, phosphorus, and potassium. Regularly including yogurt in your diet may assist with weight management, bone health, blood sugar balance, and blood pressure regulation.

Follow these tips to choose a yogurt:

• Make sure you see live, active cultures listed in the ingredients list
• Choose an unsweetened yogurt and add your own fresh fruit to control the sugar content. If you need it to be flavored, choose one that has less than seven grams of added sugar per serving
• Opt for Greek yogurt or Icelandic skyr yogurt for a higher protein content

7. Miso and Natto

Though natto and miso are both made from fermented soybeans, the two ingredients are fermented using different bacterial strains. 

What’s more, natto consists of whole fermented soybeans, while miso is a smooth paste made from fermented soybeans. 

In Japanese cooking, natto is traditionally added to rice dishes and soups, or used for sautéing vegetables. Miso paste is used much like a seasoning; it lends powerful umami flavor to many dishes. 

Both of these fermented ingredients have been associated with improving gut health, cardiovascular outcomes, and immune function.

8. Apple Cider Vinegar

Think of apple cider vinegar (ACV) as fermented apple juice. Like sauerkraut, ACV is high in acetic acid, a byproduct of fermentation. But not all apple cider vinegars (ACV) contain bacteria. Many AVCs undergo pasteurization and filtering, two processing methods that inactivate or remove microbes from the product. 

Even with raw, unpasteurized ACV, it’s not entirely clear how it will benefit your gut health. 

There’s some evidence that ingesting ACV prior to eating could help prevent blood sugar spikes after meals. Try using the vinegar in a homemade dressing and enjoying it over a salad. The combination of vinegar and fiber-vegetables may help stabilize blood glucose levels after you eat.  

How Often Should You Eat Fermented Foods for Gut Health?

There are no official recommendations for how often you should eat fermented foods, but research suggests that regularly including them into your diet may help bolster gut health and fight inflammation. 

One small 2021 study reported that people who consumed six servings of fermented foods daily for 10 weeks experienced significant reductions in inflammatory markers and an increase in gut microbiome diversity compared to study participants who doubled their dietary fiber intake (and did not eat fermented foods) during the trial.

Whether you need to consume six servings of fermented foods every day in order to reap their benefits remains to be seen. For now, try incorporating at least one fermented food into your diet daily by enjoying kefir at breakfast, sipping on some kombucha with lunch, or adding a spoonful of sauerkraut to a grain bowl at dinner. 

How to Ferment Foods at Home

To properly ferment foods at home, you will need sterilized glass jars, salt, a cloth napkin or cheesecloth, and whatever ingredients you intend to ferment. 

Here are general steps for making fermented vegetables at home:

• Combine prepared vegetables with salt. Squeeze and mix thoroughly to allow the vegetables' natural liquids to release. You may have to repeat this step multiple times in order to get enough brine.
• Next you can mix in your desired herbs and spices.
• Add the vegetables and brine to a sterilized glass jar. The vegetables should be completely submerged in liquid. Close the jar tightly, and then set it aside to be stored at room temperature.
• You may see bubbles start to form in the jar. You can gently release the lid to let the gases out once a day.
• How long you allow your vegetables to ferment will depend on the temperature at which they are kept, as well as your preferred flavor profile. This could be anywhere from three days to one month. The longer they ferment, the more tangy they will taste.
• Once fermented, the vegetables should be stored in the refrigerator, where they can stay good in the fridge for months.

Risks and Side Effects of Fermented Foods

Common side effects of eating fermented foods can include digestive symptoms, such as abdominal bloating and gas, in sensitive individuals. 

Preparing fermented foods at home without following proper food safety standards (such as not washing your hands properly or not using sterilized jars) can increase the risk of harmful microbes growing in your food. Improper storage of fermented foods can also heighten the risk of contracting a foodborne illness after consumption.

Eating fermented foods may also pose risks for people diagnosed with a histamine intolerance, those who suffer from migraines, and individuals taking monoamine oxidase inhibitors (MAOI) medications. If this is you, talk to your healthcare provider about whether regularly eating fermented foods is safe for you. 

The Difference Between Fermented Foods and Probiotic Foods

Though the terms ‘fermented’ and ‘probiotic’ are used interchangeably, they are not synonyms. Fermented ingredients are those that are produced with microorganisms (such as bacteria or yeast) and undergo chemical changes as a result. 

Probiotics are defined as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.”

Some ingredients are fermented but do not contain any active bacteria. Here are a few examples:

• Sourdough bread is made with a live starter culture, but these microbes are inactivated by heat. As such, once the bread is baked, it’s no longer a source of active microbes. 
• Wine and beer are both produced by way of yeast fermentation, but because the final products are filtered, they don't retain any live microbes.

Other fermented foods contain active bacteria, but have not yet  been confirmed to act as probiotics. According to the International Scientific Association of Probiotics and Prebiotics, in order for a fermented food to be accurately labeled as a probiotic, it must:

• Be shown in interventional studies to provide strain-specific benefits 
• Be proven safe 
• Contain a sufficient amount of that specific strain in its final form in order to deliver purported benefits 
• Based on these definitions, all of the foods listed below are fermented foods, but not all meet the definition of probiotics.
  

A Quick Review

Fermented foods include those that are either made with or contain live, active bacteria. Research suggests that regularly including fermented foods in your diet can help diversify the healthy bacteria in your gut.

If fermented foods are new to you, start slowly by incorporating one to two servings of fermented foods daily to assess your tolerance. Most fermented foods are full of compounds that help fight inflammation, as well as important vitamins and minerals,