Kefir is a fermented milk drink containing kefir grains. There are several possible health benefits to drinking kefir, but many claims lack evidence.

The name kefir comes from the Turkish word “keyif,” which refers to the “good feeling” a person gets after drinking it. The drink is a combination of milk and kefir grains and contains live bacteria and yeast.

Some people attribute kefir’s potential health benefits to its probiotic content. Probiotics are beneficial species of bacteria and other microbes. Research on probiotics is still in its early stages.

In this article, learn more about what kefir is, its health benefits, how to make it, and how it compares to other fermented dairy products in terms of nutrition.

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Kefir is a type of fermented dairy product. People make it by adding bacteria and yeast cultures to milk. The cultures feed on natural sugars in the milk. This allows them to multiply, creating a fermented drink.

Kefir has a tart and tangy flavor and a consistency similar to drinkable yogurt. Due to the fermentation process, kefir may taste slightly carbonated. This happens because the microbes produce gases as they digest the sugars in the milk.

Types

There are many types of kefir. People can purchase or make it using:

  • cow’s, sheep’s, or goat’s milk
  • nondairy milk, such as coconut or oat milk
  • juice
  • water

Some companies also make flavored or low fat kefir drinks.

Despite the name, kefir grains are unrelated to wheat or oats. This means there is no gluten in a traditional kefir drink containing only milk and live cultures.

However, some brands may use oats and other products containing gluten to add flavor or change the texture of the liquid. Always check the label before purchasing.

Many kefir drinks are based on a type of dairy milk. The fermentation process reduces how much lactose this milk contains, but this does not necessarily make kefir lactose free. There may still be trace amounts of lactose, depending on the product.

Some people with mild lactose intolerance may still tolerate kefir if the amount of lactose is minimal. Those with more severe intolerances or allergies may benefit more from a nondairy kefir.

Research into kefir’s health benefits is still in its early stages, but some evidence suggests it may help with:

Blood sugar control

A small 2015 study in Iran compared the effects of consuming kefir and conventionally fermented milk on blood sugar levels in people with diabetes. Participants who consumed kefir had significantly lower fasting blood sugar levels than those who consumed conventionally fermented milk.

A 2020 review suggests that kefir could have a range of benefits for people with diabetes and obesity. It may modulate diabetes-related markers. However, larger-scale research is necessary to support this.

Lowering cholesterol

A 2017 study looked at changes in cholesterol levels among females with obesity or overweight who drank low fat milk or kefir. The participants drank either two servings a day of low fat milk, four servings a day of low fat milk, or four servings a day of kefir.

After 8 weeks, those who drank kefir showed significant decreases in their total cholesterol levels, and in their low-density lipoprotein cholesterol levels, compared to those who drank only two servings per day of low fat milk. Participants who consumed four servings per day of low fat milk also had lower cholesterol levels.

The probiotics in kefir may play a role in how much cholesterol the body absorbs from food. They may also affect how the body produces, processes, and uses cholesterol.

Digestive health

The gut contains many species of microorganisms. Some of these species have beneficial effects on the body, while others can cause harm.

Probiotic foods contain some of the same beneficial species of bacteria that live in the digestive tract. This may mean they can help with maintaining a good balance of species. However, scientists are still learning how this works.

An animal study in 2018 found that kefir supplementation can improve the ratio of good to harmful bacteria in the gut and reduce physical fatigue during exercise in mice. More research is necessary to understand if this finding also applies to humans.

Killing pathogens

Pathogens are harmful microorganisms that can cause infections. Older research from 2013 notes that in laboratory studies, bacteria from kefir grains killed harmful bacteria such as Escherichia coli, Salmonella, and Staphylococcus aureus.

This may mean kefir can be potentially helpful for preventing infections, such as gastroenteritis or vaginal infections. However, there is little research in humans to confirm kefir has this effect.

People should not use probiotics or kefir as a substitute for medical treatment for an existing infection.

The nutritional value of kefir and the probiotic microbes it contains varies widely depending on the ingredients and fermentation technique. A 2017 paper estimates that traditional milk kefir consists of around:

  • 90% water
  • 6% natural sugars
  • 3.5% fat
  • 3% protein

Kefir also contains a number of vitamins and minerals, including:

It is possible to make kefir at home. To do this, a person will need a clean environment and equipment to prevent the wrong types of bacteria from getting into the liquid. To begin, a person will need:

  • active kefir grains, which are available for purchase
  • milk, such as cow’s, goat’s, or coconut milk
  • a glass jar
  • a paper coffee filter or cheesecloth
  • a rubber band
  • a silicone spatula or wooden spoon
  • a nonmetal mesh strainer

To make the kefir:

  1. Wash hands with soap and water.
  2. Sterilize the jar by washing with soap and hot water. Leave to air-dry upside down on a clean drying rack.
  3. When dry, add milk to the glass jar. Combine 1 teaspoon of kefir grains for every cup of milk. Leave space at the top, as the liquid will expand as it ferments.
  4. Cover the jar with the paper coffee filter and secure it with a rubber band. Store the jar in a warm place at around 70°F (21°C) for 12–48 hours. Keep the jar away from direct sunlight, and shake gently if the liquid starts to separate.
  5. Once the liquid has thickened, pour it through the mesh strainer into a sterile storage container. Cover tightly and store for up to 1 week in the refrigerator.

A shorter fermentation will produce sweeter kefir, while longer fermentation creates a more sour drink. People can keep the kefir grains they catch in the strainer to use in their next batch of kefir.

How to use kefir

People can use kefir in the same way as milk and pouring yogurt. Try:

  • drinking chilled in a glass
  • pouring on cereal, oats, or muesli
  • adding to smoothies
  • eating with fruit

People can also use kefir in creamy salad dressings, iced yogurt, baked goods, and soups. However, be aware that heating the kefir will deactivate the live cultures.

There is little research on kefir’s potential risks. It appears to be generally safe to consume, as long as people make and store it safely.

While people who are lactose intolerant may be able to drink some kefir without symptoms, they should be careful to avoid drinking too much. People with milk allergies should avoid kefir unless it contains nondairy milk.

People with diabetes should be careful to read the label and stick to plain varieties without added sugar.

Kefir, yogurt, and buttermilk are all types of fermented dairy products. However, they have slightly different properties.

Kefir and yogurt are very similar, as they both consist of milk fermented with beneficial bacteria. They have similar nutritional profiles, are relatively low in fat, and are a source of protein. It is also possible to make both with dairy-free milk alternatives, and people can use them in foods in similar ways.

Buttermilk is different from yogurt and kefir. It is a thin liquid that occurs as a byproduct of churning butter. Some buttermilk contains live cultures, but not all. It contains mostly water, lactose, and casein, which is a type of protein in milk.

People typically use buttermilk for baking but may also drink it.

Learn more about the differences between yogurt and kefir.

Kefir is a fermented drink that contains live bacteria and yeast. Some studies suggest these microbes are potentially beneficial to health. They may help control blood sugar, aid digestive health, and lower cholesterol.

However, more high-quality research is necessary to confirm these effects in humans, as many of the studies so far have been small or involved animals rather than people.

Scientists do know that milk kefir is a good source of protein, calcium, and potassium. Plain milk kefir is also relatively low in sugar and fat. People can use kefir in their diet in a similar way to yogurt.