Fermentation is a process that involves the breakdown of sugars by bacteria and yeast.
Not only does this help enhance the preservation of foods, but eating fermented foods can also boost the number of beneficial bacteria, or probiotics, found in your gut.
Probiotics have been associated with a variety of health benefits, including improved digestion, better immunity and even increased weight loss (, , ).
This article looks at 8 fermented foods that have been shown to improve health and digestion.
Kefir is a type of cultured dairy product.
It is made by adding kefir grains, which are made up of a combination of yeast and bacteria, to milk. This results in a thick and tangy beverage with a taste that is often compared to yogurt.
Studies have shown that kefir may come with many benefits, affecting everything from digestion to inflammation to bone health.
In one small study, kefir was shown to improve the digestion of lactose in 15 people with lactose intolerance. Those who are lactose intolerant are unable to digest the sugars in dairy products, resulting in symptoms like cramps, bloating and diarrhea ().
Another study found that consuming 6.7 ounces (200 ml) of kefir daily for six weeks decreased markers of inflammation, a known contributor to the development of chronic diseases like heart disease and cancer (, )
Kefir may also help enhance bone health. One study looked at the effects of kefir on 40 people with osteoporosis, a condition characterized by weak, porous bones.
After six months, the group consuming kefir was found to have improved bone mineral density, compared to a control group ().
Enjoy kefir on its own or use it to give your smoothies and blended drinks a boost.
Summary: Kefir is a fermented dairy product that may improve lactose digestion, decrease inflammation and boost bone health.
Tempeh is made from fermented soybeans that have been pressed into a compact cake.
This high-protein meat substitute is firm but chewy and can be baked, steamed or sautéed before being added to dishes.
In addition to its impressive probiotic content, tempeh is rich in many nutrients that may better your health. For example, soy protein has been shown to reduce certain risk factors for heart disease.
One study in 42 people with high cholesterol looked at the effects of eating either soy protein or animal protein. Those eating soy protein had a 5.7% decrease in “bad” LDL cholesterol, a 4.4% reduction in total cholesterol and a 13.3% reduction in blood triglycerides ().
Additionally, a test-tube study found that certain plant compounds in tempeh could act as antioxidants, helping reduce the buildup of free radicals, which are harmful compounds that can contribute to chronic disease ().
Tempeh is perfect for vegetarians and meat-eaters alike. Use it for anything from sandwiches to stir-fries to take advantage of its many health benefits.
Summary: Tempeh is made from fermented soybeans. It is high in probiotics and contains compounds that may act as antioxidants and improve heart health.
Natto is a staple probiotic food in traditional Japanese cuisine and, like tempeh, made from fermented soybeans.
It contains a good amount of fiber, providing 5 grams per 3.5-ounce (100-gram) serving ().
Fiber may help support digestive health. It moves through the body undigested, adding bulk to stool to help promote regularity and alleviate constipation ().
Natto is also high in vitamin K, an important nutrient that’s involved in the metabolism of calcium and plays a major role in bone health. In one study of 944 women, natto intake was associated with reduced bone loss in those who were postmenopausal ().
The fermentation of natto also produces an enzyme called nattokinase. One study in 12 people showed that supplementing with nattokinase helped prevent and dissolve blood clots ().
Another study also found that supplementing with this enzyme helped reduce systolic and diastolic blood pressure by 5.5 and 2.84 mmHg, respectively ().
Natto has a very strong flavor and slippery texture. It is often paired with rice and served as part of a digestion-boosting breakfast.
Summary: Natto is a fermented soybean product. Its high fiber content may promote regularity and help prevent bone loss. It also produces an enzyme that can reduce blood pressure and help dissolve blood clots.
Kombucha is a fermented tea that is fizzy, tart and flavorful. It is made from either black or green tea and contains their potent health-promoting properties.
Animal studies show that drinking kombucha could help prevent liver toxicity and damage caused by exposure to harmful chemicals (, , ).
Test-tube studies have also found that kombucha could help induce cancer cell death and block the spread of cancer cells (, ).
One animal study even found that kombucha helped reduce blood sugar, triglycerides and LDL cholesterol ().
Although most of the current research is limited to test-tube and animal studies, the benefits of kombucha and its components are promising. Nevertheless, further studies are needed to determine how kombucha may affect humans.
Thanks to its rising popularity, kombucha can be found at most major grocery stores. It can also be made at home, though it should be prepared carefully to prevent contamination or over-fermentation.
Summary: Kombucha is a fermented tea. Although more research is needed, animal and test-tube studies have found that it could help protect the liver, decrease blood sugar and reduce levels of cholesterol and triglycerides.
Miso is a common seasoning in Japanese cuisine. It’s made by fermenting soybeans with salt and koji, a type of fungus.
It is most often found in miso soup, a flavorful dish made up of miso paste and stock that is traditionally served for breakfast.
In addition to its probiotic content, several studies have found health benefits tied to miso.
In one study including 21,852 women, consuming miso soup was linked to a lower risk of breast cancer ().
Miso may also help lower blood pressure and protect heart health. In fact, a study in rats found that the long-term consumption of miso soup helped normalize blood pressure ().
Another study in over 40,000 people showed that a higher intake of miso soup was associated with a lower risk of stroke ().
Remember that many of these studies show an association, but they don’t take other factors into consideration. More studies are needed to evaluate miso’s health effects.
Besides stirring miso into soup, you can try using it to glaze cooked vegetables, spice up salad dressings or marinate meat.
Summary: Miso is a seasoning made from fermented soybeans. It has been associated with a reduced risk of cancer and improved heart health, though more human studies are needed.
Kimchi is a popular Korean side dish that is usually made from fermented cabbage, although it can also be made from other fermented vegetables like radishes.
It boasts an extensive array of health benefits and may be especially effective when it comes to lowering cholesterol and reducing insulin resistance.
Insulin is responsible for transporting glucose from the blood to the tissues. When you sustain high levels of insulin for long periods, your body stops responding to it normally, resulting in high blood sugar and insulin resistance.
In one study, 21 people with prediabetes consumed either fresh or fermented kimchi for eight weeks. By the end of the study, those consuming fermented kimchi had decreased insulin resistance, blood pressure and body weight ().
In another study, people were given a diet with either a high or low amount of kimchi for seven days. Interestingly, a higher intake of kimchi led to greater decreases in blood sugar, blood cholesterol and “bad” LDL cholesterol ().
Kimchi is easy to make and can be added to everything from noodle bowls to sandwiches.
Summary: Kimchi is made from fermented vegetables such as cabbage or radishes. Studies have found that it may help reduce insulin resistance and blood cholesterol.
Sauerkraut is a popular condiment consisting of shredded cabbage that has been fermented by lactic acid bacteria. It is low in calories but contains plenty of fiber, vitamin C and vitamin K ().
It also contains a good amount of lutein and zeaxanthin, two antioxidants that help promote eye health and reduce the risk of eye disease ().
The antioxidant content of sauerkraut may also have promising effects on cancer prevention.
One test-tube study showed that treating breast cancer cells with cabbage juice decreased the activity of certain enzymes related to cancer formation ().
However, the current evidence is limited and more research is needed to look at how these findings may translate to humans.
You can use sauerkraut in just about anything. Throw it in your next casserole, add it to a hearty bowl of soup or use it to top off a satisfying sandwich.
To get the most health benefits, be sure to choose unpasteurized sauerkraut, as the process of pasteurization kills off beneficial bacteria.
Summary: Sauerkraut is made from shredded cabbage that has been fermented. It is high in antioxidants that are important for eye health, and it’s easy to add to many dishes.
Yogurt is produced from milk that has been fermented, most commonly with lactic acid bacteria.
It is high in many important nutrients, including calcium, potassium, phosphorus, riboflavin and vitamin B12 ().
Yogurt has also been associated with a wide variety of health benefits.
One review of 14 studies showed that fermented milk products like probiotic yogurt could help reduce blood pressure, especially in those with high blood pressure ().
Another study found that a higher intake of yogurt was linked to improvements in bone mineral density and physical function in older adults ().
It may also help keep your waistline in check. A recent review showed that eating yogurt was associated with a lower body weight, less body fat and a smaller waist circumference ().
Remember that not all yogurt varieties contain probiotics, as these beneficial bacteria are often killed during processing.
Look for yogurts that contain live cultures to make sure you’re getting your dose of probiotics. Additionally, make sure to opt for yogurts with minimal added sugar.
Summary: Probiotic yogurt is made from fermented milk. It is high in nutrients and could help reduce body weight, lower blood pressure and improve bone health.
Fermentation can help increase both the shelf life and health benefits of many different foods.
The probiotics found in fermented foods have been associated with improvements in digestion, immunity, weight loss and more (, , ).
In addition to containing these beneficial probiotics, fermented foods can positively impact many other aspects of health and are an excellent addition to your diet.