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What to know about kefir, one of the original gut-friendly foods

This fermented dairy drink can boost your digestive system and your health

Kefir is made from cow or goat milk and live cultures called “kefir grains,” which are composed of bacteria and yeast. (Stevica Mrdja/Getty Images)

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For several years now, foods that are said to promote gut health have been wildly popular. You see probiotic-enhanced almonds, apricots, chocolate, fruit juice, snack bars, soft drinks and more on store shelves. But if you really want to do something for your digestive system — and your overall health — try one of the original gut-friendly foods: kefir.

What is kefir?

Kefir (pronounced kuh-FEER) is yogurt’s tangier, sometimes fizzy cousin with the creamy consistency of a yogurt drink. It has been around for thousands of years. It’s made from cow or goat milk and live cultures that are called “kefir grains,” which look grainlike but are clumps of gel-like microbes composed of bacteria and yeast. Milk is poured over the grains, which can be reused indefinitely. The kefir grains ferment the natural sugar in the milk, called lactose, and 24 hours later you have the milk-based drink.

Like yogurt, kefir has little to no lactose, so it may be suitable for people who have lactose intolerance and experience gas, bloating and diarrhea after eating or drinking dairy products.

Benefits of its probiotics

Many fermented foods have healthy probiotic bacteria. “Most people know that yogurt contains good-for-you bacteria,” Consumer Reports nutritionist Amy Keating says. “But it is only required to have two bacterial strains,” although some yogurts have more. Kefir can have upward of 50 yeast and bacteria strains, some sources suggest. “You don’t need to replace yogurt, but kefir is a great addition to the diet because it has a higher and more diverse probiotic bacteria content,” Keating says.

Kefir has a good amount and variety of healthy microbes, and the diversity makes the probiotics more likely to replicate in the gut, says Fasih Hameed, an integrative family medicine doctor at Petaluma Health Center in Petaluma, Calif. A good array of probiotics in your system has benefits for not only gut health but also overall health, he says.

Probiotics help break down food, synthesize vitamins, prevent bacteria that cause illness from getting a foothold, and may even bolster immunity.

“Probiotics produce bioactive compounds, such as short-chain fatty acids that have anti-inflammatory effects that can help systemic issues like cholesterol management and neurotransmitter synthesis,” says Sotiria Everett, clinical assistant professor of family, population and preventive medicine at Stony Brook Medicine in Stony Brook, N.Y.

Many studies have uncovered these benefits, including a recent one out of Stanford University that compared a high-fiber diet (which is also known to affect the gut’s population of healthy bacteria) with a fermented-food diet including kefir.

In this small study, the researchers found that the fermented-food diet both increased microbiome diversity and decreased markers of inflammation in the body. Other scientific studies conducted on the functionality of kefir have indicated that it may have anti-bacterial, anti-tumor, anti-carcinogenic and cholesterol-lowering effects.

“Our gut plays such a tremendous role in our total health,” Everett says. “Anything we eat that will benefit or influence our gut is favorable.”


Kefir’s nutrition is similar to that of yogurt, supplying protein and calcium. The nutrient amounts vary slightly from brand to brand, but one cup of Lifeway Plain Lowfat Kefir has 110 calories, 11 grams of protein (22 percent of the daily value), 2 grams fat, 1.5 grams saturated fat, 9 grams carbs, 0 grams added sugars and 390 mg calcium (30 percent of the daily value).

Unflavored kefir is the best choice. “One thing I would recommend right off the bat is a plain flavor that isn’t high in [added] sugar,” Everett says. If you want a fruity drink, she suggests putting kefir in a blender with some frozen berries or other fruit.

You can also pour kefir over cereal or granola or use it as the liquid in your overnight oats. If you opt for a flavored kefir, look for one that has no more than 6 grams of added sugars.

Copyright 2022, Consumer Reports Inc.

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