12 Fermented Foods to Boost Digestion

Fermented foods have been around for centuries as fermentation is one of the oldest methods of food preservation. While well known for extending the shelf life of foods, more recent research has shown that fermenting foods also provide a host of other health benefits, including probiotic bacteria. Here is a list of the best fermented foods to boost digestion and support gut health.

What are fermented foods?

Fermented foods are foods and beverages that undergo controlled microbial growth and enzymatic action through fermentation ^{(1, 2)}. Fermentation is a chemical process by which beneficial bacteria, yeasts, and microorganisms break down food components, such as glucose, to create organic acids, carbon dioxide, and alcohol.

Fermented foods are some of the first processed food products consumed by humans, as fermentation is an ancient and natural method of food preservation. These byproducts produced during the fermentation process create an acidic and inhospitable environment that inhibits the growth of spoilage and pathogenic microorganisms, extending the shelf life and improving the safety of the food.

Health Benefits of Fermented Foods

While fermented foods have been around for thousands of years and were largely praised for their long shelf life and organoleptic properties (i.e. their taste and texture), recent scientific research has begun to show the positive health benefits associated with their consumption. The potential health benefits of fermented foods include ⁽³⁾:

• Increased probiotic activity
• Increased antioxidant activity
• Increased vitamin bioavailability
• Improved protein digestibility
• Alleviation of lactose intolerance
• Improvements in blood pressure
• Anti-diabetic properties
• Reduction of FODMAPs
• Reduction of “antinutrients”

While many fermented foods contain probiotics, not all fermented foods do. Probiotics are tiny microorganisms, including live bacteria and yeast, that live in the gut and are beneficial for health. However, some foods undergo steps that remove the probiotics, like beer and wine, or make them inactive, like baking and canning ^{(4, 5)}.

Moreover, certain fermented foods are also sources of prebiotics; a special form of indigestible plant fiber in fiber-rich carbohydrate foods which encourages the growth of probiotic bacteria. Together, prebiotics and probiotics build and maintain a healthy colony of bacteria in our gut, which supports our overall health and well-being.

How often should you eat fermented foods?

There is no recommended daily allowance for fermented foods. Consuming them daily, or multiple times per day in small amounts, as part of a well-balanced diet can help to reap their potential health benefits.

List of Fermented Foods

While it is difficult to determine the total number of fermented foods produced worldwide, estimates suggest there are more than 5000 different kinds ⁽⁶⁾. Here is a list of some of the most well-known and popular fermented foods.

1. Kefir

Kefir is a fermented milk product and a great source of probiotics. It is made by adding kefir grains – small colonies of yeast and bacteria that resemble cauliflower or popcorn – to milk, which ferments to produce a thick and tangy beverage resembling yogurt. Kefir can be made from any animal milk, including cow’s, goat’s, or sheep’s milk, and can be consumed by drinking it on its own or adding it to smoothies, granola, parfaits, or baked goods.

2. Sauerkraut

Sauerkraut is a fermented food made of fermented cabbage and has its root in Eastern European diets. Sauerkraut is the German term for “sour cabbage” and is made by mixing fresh cabbage and salt, pressing down on the mixture, which releases water and causes fermentation. Sauerkraut is a source of probiotics and has a crunchy texture and tangy flavor and can be eaten on its own or piled onto dishes of meat and potatoes, beef stew, and eggs.

3. Tempeh

Tempeh is a traditional Indonesian food made from fermented soy beans pressed into a cake-like form. While similar to tofu, tempeh has a firmer texture and nuttier flavor and is one best sources of plant-based protein. Tempeh is a good source of probiotics and the fermentation process used to make it lowers the amount of phytic acid present in the soy beans, making its nutrients easier to digest and absorb ^{(7, 8)}. Tempeh can be baked, steamed, roasted, or sautéed into stir-fry dishes.

4. Kimchi

Kimchi is a traditional Korean side dish made of salted and fermented vegetables. Although the most well-known version of kimchi is made from salted napa cabbage and spices, there are hundreds of varieties. Kimchi is primarily a probiotic food; however, certain varieties may also contain prebiotic fiber depending on the ingredients.

Kimchi is typically found in the refrigerated section of the grocery store near pickles and sauerkraut, and can be added to dishes of meat, rice bowls, ramen, or bibimbap, but can also be eaten on its own.

5. Kombucha

Kombucha is a fermented tea beverage. Thought to have originated in China, kombucha is made by fermenting sugary tea with SCOBY; an acronym for Symbiotic Culture of Bacteria and Yeast, to create a fizzy, slightly tart, and mostly non-alcoholic beverage. The fermentation process of kombucha results in the presence of lactic acid bacteria, making it a good source of probiotics ⁽⁹⁾.

Thanks to its rising popularity, kombucha is now easily found at most large grocery store chains in a variety of different flavors, however, it’s important to read the label as some varieties can be high in added sugar ⁽¹⁰⁾.

6. Miso

Miso is a Japanese seasoning that is made by fermenting soy beans with salt and a fungus called kōji that’s been cultivated from rice or soybeans ⁽¹¹⁾. Over weeks, sometimes years, the enzymes in the kōji work to break down the structure of the beans to create different probiotic-rich varieties of miso such as white, yellow, red, and brown.

With its salty, earthy, and slightly funky flavor, miso can be used as a condiment and flavoring in broths, marinades, salad dressings, or seasoning for fish and meats.

7. Yogurt

Yogurt is one of the most well-known fermented foods as it is common in many cuisines around the world. It is made from cultured milk, specifically through a fermentation process with lactic acid bacteria, and is present in Greek yogurt, skyr, and plain yogurt. Yogurt is traditionally made from dairy milk, however, can also be made from non-dairy milk, such as coconut milk, to create non-dairy yogurt.

While all yogurt contains contain bacterial cultures, not all bacterial cultures will have a probiotic effect. To know if yogurt contains probiotics, look for labels that explicitly mention “live and active cultures” or list specific probiotic strains.

8. Natto

Natto is also a traditional Japanese dish made of fermented soybeans, has a slimy, sticky, and stringy texture, and contains a bacterial strain called Bacillus subtilis ⁽¹²⁾. Although less common in North American cuisine, natto is commonly paired with rice as a breakfast dish, but because of its strong flavor and texture, it is a bit more of an acquired taste.

9. Cheese

Cheese has a long history of being a fermented dairy product and the fermentation process has been used to create a range of unique flavors. While all milk starts at about the same pH, and most cheeses finish at a similar pH, the rate of acidification, or how fast the pH drops, is vital for creating different types of cheese ⁽¹³⁾. While all cheeses are fermented, not all cheeses contain probiotics. Similar to yogurt, in order to be considered one of the probiotic foods, cheese must contain live and active cultures as an ingredient.

10. Fermented Vegetables

In the same way, cabbage is fermented for sauerkraut and kimchi, other vegetables can be made into fermented foods. Cucumbers, radishes, carrots, cauliflower, and peppers can all be fermented, preserved, and turned into good sources of probiotics.

That said, it’s important not to confuse fermenting with pickling, as pickled vegetables do not undergo a fermentation process. Pickling uses an acidic brine, such as vinegar, while fermentation relies on the natural bacteria in the food to produce lactic acid. For a vegetable to be fermented and contain probiotics, it must be mixed in a solution of salt and water to naturally produce lactic acid bacteria.

11. Sourdough Bread

Sourdough bread is a popular fermented food and an ancient breadmaking technique. The process of making sourdough relies on a “starter”; a mixture of flour and water fermented by naturally occurring wild yeasts and lactic acid bacteria. The wild yeast consumes the natural sugars in the flour and produces carbon dioxide, which helps to leaven the dough, and the lactic acid contributes to its unique sour flavor.

While sourdough bread does not contain probiotics, as the bacteria do not survive the baking process, the natural fermentation process reduces antinutrients found in the grains and improves the overall digestibility of bread ^{(7, 8)}.

12. Apple Cider vinegar

Apple cider vinegar is a fermented food made from apple juice. It is made via a two-step fermentation process which converts apple juice into vinegar; apples are crushed, juice, and fermented by yeast to convert the sugars into alcohol, and then acetic acid-forming converts the alcohol into acetic acid to produce apple cider vinegar ⁽¹⁴⁾.

Many foods, including grapes, oranges, maple syrup, and honey, can be used to produce vinegar, however, the compounds in apples give apple cider vinegar a particularly sweet and crisp flavor. Apple cider vinegar, also known as ACV, can be used in coleslaw, salad dressings, marinades, or to pickle vegetables.

The Bottom Line

Fermented foods are foods and beverages that have undergone controlled microbial growth and enzymatic action. The fermentation process has been shown to increase the health benefits of foods by producing probiotic bacteria, increasing antioxidants, and improving vitamin availability in certain foods. The most popular traditional fermented foods include kefir, sauerkraut, tempeh, kimchi, kombucha, miso, yogurt, fermented vegetables, natto, sourdough bread, cheese, and apple cider vinegar.