Fermentation is a process in which bacteria and yeast break down sugars.
Not only does fermentation enhance food preservation, but eating fermented foods can also boost the number of beneficial bacteria, or probiotics, in your gut.
Probiotics are associated with a variety of health benefits, including improved digestion and better immunity, as well as increased weight loss (
Here are 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 a combination of yeast and bacteria — to milk. This results in a thick, tangy beverage that tastes similar to yogurt.
Studies suggest that kefir offers numerous health benefits. It’s believed to aid digestive health and reduce inflammation.
In animal studies, kefir improved immune function by stimulating the body to produce anti-inflammatory substances. Animals fed kefir were also more successful at fending off intestinal infections (
However, more research is needed to understand the effects of kefir in humans.
One older study found that consuming 6.7 ounces (oz) (200 milliliters) of kefir daily for 6 weeks decreased markers of inflammation, which is known to contribute to chronic conditions such as heart disease and cancer (
Kefir contains less lactose than milk. When kefir grains and milk are combined, the bacteria in the grains help ferment and break down the lactose in the milk. But kefir does contain some lactose, so it may not be appropriate for everyone with lactose intolerance (7).
This tangy drink may also boost bone health.
In a 6-month study of 40 people with osteoporosis — a condition characterized by weak, porous bones — those who drank kefir had improved bone mineral density compared with the control group (
You can enjoy kefir on its own or blend it into smoothies and drinks.
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 sauteed before being added to dishes.
In addition to its impressive probiotic content, tempeh is rich in many nutrients that may improve your health (
For example, soy protein has been shown to help reduce certain risk factors for heart disease.
One review of more than 40 studies noted that eating 25 grams (g) (0.88 oz) 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, an older test-tube study found that certain plant compounds in tempeh may act as antioxidants. Antioxidants reduce the buildup of free radicals, which are harmful compounds that can contribute to chronic disease (11).
Tempeh is a great option for vegetarians and omnivores alike. It’s particularly suited to dishes such as sandwiches and stir-fries.
Tempeh is made from fermented soybeans. It’s high in probiotics, may boost heart health, and may even offer antioxidants.
Natto is a staple probiotic food in traditional Japanese cuisine.
Like tempeh, it’s made from fermented soybeans. It has a strong flavor and a slimy texture.
It contains a good amount of fiber, providing 5.4 g per 3.5-oz (100-g) serving (
Fiber supports digestive health by moving through your body undigested, adding bulk to stool. This helps promote regularity and alleviate constipation (
Natto is also high in vitamin K, an important nutrient involved in calcium metabolism and bone health (
In studies involving hundreds of Japanese women, natto intake was associated with reduced bone loss in those who were postmenopausal (
The fermentation of natto also produces an enzyme called nattokinase. In studies, high doses of this enzyme have been used to treat blood clots and lower blood pressure. However, the amount of nattokinase in a portion of natto can vary, and taking a high dose supplement is not the same as eating natto (
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 bowel regularity and help prevent bone loss. It also produces an enzyme that may reduce blood pressure and dissolve blood clots.
Kombucha is a fermented tea that’s fizzy, tart, and flavorful. It’s made from either green or black tea and offers these drinks’ potent health-promoting properties.
Animal studies suggest that drinking kombucha may help protect the liver from damage caused by exposure to harmful chemicals (
Plus, test-tube studies have found that kombucha may help induce cancer cell death and prevent the spread of cancer cells (
Some animal studies have even found that kombucha may help decrease blood sugar, triglyceride, and LDL (bad) cholesterol levels (
Kombucha’s antioxidant content is thought to be responsible for many of its possible positive effects (
Although these results are promising, further human research is needed (26).
Thanks to its rising popularity, kombucha can be found at most major grocery stores. But be sure to read the nutrition label and ingredients so you know what’s in the bottle.
Many kombucha drinks are high in added sugar, and others may contain sugar substitutes such as sugar alcohols, which some people may prefer to avoid (27).
You can make kombucha at home, but 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 suggest that it could help protect the liver, decrease blood sugar, and lower cholesterol and triglyceride levels.
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 of miso paste and stock. Miso soup is traditionally served for breakfast.
Several studies have found health benefits tied to miso.
An older study in 21,852 Japanese women suggested that eating miso soup was linked to a lower risk of breast cancer (
Another older study involving more than 40,000 people associated a higher intake of miso soup with a lower risk of stroke in Japanese women (
Miso may also help lower blood pressure and protect heart health. A 2014 study in rats found that long-term miso soup intake helped normalize blood pressure levels (
Plus, a study in middle-aged and older Japanese adults found that frequent miso soup intake may lead to a lower heart rate. This study also concluded that miso soup did not elevate blood pressure, despite its saltiness (
However, miso’s high salt content may carry other health risks. In particular, Japanese researchers have linked miso soup intake to a higher risk of stomach cancer. This type of cancer is associated with a high sodium diet (32).
One 2016 study found that eating 3–4 cups of miso soup per day raised the risk of stomach cancer, and a 2017 review concluded that men who ate 1–5 cups per day had an increased risk of stomach cancer (32,
Overall, 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 associated with improved heart health and a 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 or other fermented veggies, such as radishes.
It boasts an extensive array of health benefits and may be especially effective at 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 as usual, resulting in high blood sugar levels and insulin resistance.
In one study, 21 people with prediabetes ate either fresh or fermented kimchi for 16 weeks. At the end of the study, those who ate fermented kimchi had decreased insulin resistance, blood pressure, and body weight (
In another study, people consumed either 7.4 oz (210 g) of kimchi or 0.5 oz (15 g) of kimchi per day for 7 days. The researchers found that higher kimchi intake led to greater decreases in blood sugar, 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 and radishes. Studies have found that it may help reduce insulin resistance and cholesterol levels.
Sauerkraut is a popular condiment consisting of shredded cabbage that has been fermented by lactic acid bacteria. It’s low in calories but contains plenty of fiber and vitamins C and K (
Like other foods made with leafy green vegetables, it contains good amounts of lutein and zeaxanthin, antioxidants that can help promote eye health and reduce your risk of eye disease (37).
Sauerkraut may also support digestive health. In a small Norwegian study of 34 people with irritable bowel syndrome (IBS), those who added sauerkraut to their diet saw significant improvements in IBS symptoms (
You can use sauerkraut in countless dishes, including casseroles, soups, and sandwiches.
To get the most health benefits, consider choosing unpasteurized sauerkraut. Pasteurization kills beneficial bacteria.
Sauerkraut is made from fermented shredded cabbage. It’s high in antioxidants that are important for eye health, and it may support digestive health.
Yogurt is made from milk that has 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 concluded that fermented milk products, including probiotic yogurt, may help reduce blood pressure — especially in those with high blood pressure (40).
Another study linked a higher intake of yogurt to improvements in bone mineral density and physical function in older adults (41).
This creamy dairy product may also help prevent weight gain. A review funded by the Danone Institute International associated eating yogurt with a lower body weight, less body fat, and a smaller waist circumference (
Remember that not all yogurts contain probiotics, since 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, opt for products with minimal sugar.
Probiotic yogurt is made from fermented milk. It’s high in nutrients and may help reduce body weight, lower blood pressure, and improve bone health.
What foods are considered fermented?
The term “fermented foods” refers to any foods that have undergone fermentation, the chemical breakdown of sugar by yeast and bacteria (
This category includes all the foods mentioned above:
- probiotic yogurt
Can fermented food be toxic?
Although most fermented foods are generally considered safe, some varieties — including fermented milk products such as kefir — are more susceptible to contamination with toxins and bacteria (
Fortunately, advances in processing methods and quality control have reduced the risk of contamination and spoilage in commercially available fermented foods. Practicing proper food safety when storing and handling fermented foods can further reduce the risks (
How often should you eat fermented foods?
While there are currently no official guidelines regarding how often you should eat fermented foods, adding a few servings to your daily diet may be beneficial (
For the best results, start by eating one or two servings per day, and then slowly work your way up.
Getting probiotics from whole foods is a simple way to take advantage of fermented foods’ health benefits while reducing your risk of side effects associated with probiotic use, such as digestive issues (
Fermentation may help increase both the shelf life and the health benefits of many foods.
The probiotics in fermented foods have been associated with improvements in digestion and immunity, weight loss, and more (
In addition to containing these beneficial probiotics, fermented foods aid in many other aspects of health and are an excellent addition to your diet.
Just one thing
Try this today: For an easy way to up your intake of fermented foods, try making a few simple adjustments to your diet. You can add probiotic yogurt to your parfaits, mix kimchi into rice bowls, and trade bacon for tempeh bacon.