Fermentation is a process that involves bacteria and yeast breaking down sugars.
Not only does fermentation help enhance food preservation, but eating fermented foods can also boost the number of beneficial bacteria, or probiotics, found in your gut.
This article looks at 8 fermented foods and drinks that have been shown to improve health and digestion.
Kefir is a type of cultured dairy product.
It’s 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’s 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 2003 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. This results in symptoms such as cramps, bloating, and diarrhea (
In addition to helping improve lactose digestion, kefir contains less lactose than milk. When kefir grains and milk are combined to make the kefir drink, the bacteria in the kefir grains help ferment and break down the lactose in the milk (5).
Another study found that consuming 6.7 ounces (200 milliliters) of kefir daily for 6 weeks decreased markers of inflammation, a known contributor to the development of chronic conditions such as 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 6 months, the group consuming kefir was found to have improved bone mineral density compared with the control group (
Enjoy kefir on its own or use it to give your smoothies and blended drinks a boost.
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.
For example, soy protein has been shown to help reduce certain risk factors for heart disease.
A 2019 review, which included more than 40 studies, looked at the effects of eating soy protein. Consuming 25 grams (0.88 ounces) of soy protein every day for 6 weeks led to a 3.2% decrease in LDL (bad) cholesterol and a 2.8% decrease in total cholesterol (
Additionally, a test-tube study found that certain plant compounds in tempeh could act as antioxidants. This helps reduce the buildup of free radicals, which are harmful compounds that can contribute to chronic disease (11).
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.
Tempeh is made from fermented soybeans. It’s high in probiotics and contains compounds that may act as antioxidants and help improve heart health.
Natto is a staple probiotic food in traditional Japanese cuisine.
Like tempeh, it’s made from fermented soybeans. It has a very strong flavor and slippery texture.
It contains a good amount of fiber, providing 5.4 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 (
The fermentation of natto also produces an enzyme called nattokinase. In a study of 12 young Japanese men, one-time supplementation with nattokinase helped prevent and dissolve blood clots (
Other studies also found that supplementing with this enzyme helped reduce diastolic and systolic blood pressure.
In a Japanese study lasting 8 weeks, diastolic and systolic blood pressure dropped by 2.84 and 5.55 millimeters of mercury (mmHg), respectively. In a North American study also lasting 8 weeks, diastolic and systolic blood pressure dropped by 3 and 4 mmHg, respectively (
Natto is often paired with rice and served as part of a digestion-boosting breakfast.
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 help reduce blood pressure and dissolve blood clots.
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 (26).
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 overfermentation.
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’s most often found in miso soup, a flavorful dish made up of miso paste and stock. Miso soup is traditionally served for breakfast.
Several studies have found health benefits tied to miso.
In a 2003 study involving 21,852 Japanese women, consuming miso soup was linked to a lower risk for breast cancer (
A 2007 study of more than 40,000 people showed that a higher intake of miso soup was associated with a lower risk for stroke in Japanese women (
Miso may also help lower blood pressure and protect heart health. In fact, a study in rats found that long-term consumption of miso soup helped normalize blood pressure (
A study in middle-aged and older Japanese adults found that frequent consumption of miso soup might lead to a lower heart rate. This study also concluded that miso soup didn’t elevate blood pressure, despite its saltiness (
However, other Japanese studies have linked frequent consumption of miso soup, and its large amounts of salt, to a higher risk of stomach cancer.
In one study, an increased risk of stomach cancer was associated with eating at least 3 or 4 cups of miso soup per day. In another study, males who ate 1–5 cups per day saw their risk of stomach cancer increase (31,
Many of these studies show an association between miso consumption and better health, 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
- marinate meat
Miso is a seasoning made from fermented soybeans. It’s been associated with improved heart health and reduced risk of certain cancers, though more human studies are needed.
Kimchi is a popular Korean side dish that’s usually made from fermented cabbage. It can also be made from other fermented vegetables such as 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 your blood to your 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 8 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 7 days. People in the first group received 210 grams (7.4 ounces) of kimchi a day. People in the second group received only 15 grams (0.52 ounces).
Interestingly, a higher intake of kimchi led to greater decreases in blood sugar, blood cholesterol, and LDL (bad) cholesterol (
Kimchi is easy to make and can be added to everything from noodle bowls to sandwiches.
Kimchi is made from fermented vegetables such as cabbage or radishes. Studies have found that it may help reduce insulin resistance and blood cholesterol.
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, since the process of pasteurization kills off beneficial bacteria.
Sauerkraut is made from shredded cabbage that has been fermented. It’s high in antioxidants that are important for eye health, and it’s easy to add to many dishes.
Yogurt is produced from milk that’s been fermented, most commonly with lactic acid bacteria.
It’s 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 such as probiotic yogurt could help reduce blood pressure, especially in those with high blood pressure (39).
Another study found that a higher intake of yogurt was linked to improvements in bone mineral density and physical function in older adults (40).
It may also help prevent weight gain. A 2015 review suggested 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.
Probiotic yogurt is made from fermented milk. It’s 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 foods.
In addition to containing these beneficial probiotics, fermented foods can have a positive impact on many other aspects of health and are an excellent addition to your diet.