Ask the Doctors by Eve Glazier, M.D. and Elizabeth Ko, M.D

Fermented Kefir Currently the Food Fad of the Moment

Dear Doctor: Is kefir really the miracle food that it's cracked up to be? I'll confess that fermented milk does not sound very appealing to me. What is it, exactly? And how much should I consume a day?

Dear Reader: If you've paid attention to food trends over the years, you've seen fads and enthusiasms come and go. This year's super-food becomes next year's shrug of the shoulder. Kale, kombucha, green tea, quinoa, acai berries, oatmeal, salmon and even orange juice have each had their heyday in the headlines.

Now it appears that kefir, a fermented drink traditionally made from the milk of cows, goats or sheep, is having its moment. If you've never tried it, kefir is sometimes mildly effervescent, has a silky texture that is slightly thicker than milk, and has the sharp tang of plain yogurt. It's a good source of protein, calcium and B vitamins, and delivers a generous dose of a range of gut-friendly bacteria. In a time of intense interest in probiotics, it's this last quality that has helped propel kefir into the super-food category.

Kefir comes to us from the Caucasus Mountains, and has long been part of the food traditions of Eastern Europe, Russia and Southwest Asia. It's made by inoculating milk with a substance known as kefir grains. These kefir grains are made up of lactic acid bacteria and beneficial yeasts that are held in a matrix of fats, sugars and proteins. They form irregular clusters that can look a bit like cauliflower florets.

The kefir grains break down the sugars in milk to form lactic acid, which imparts a sour flavor. It also renders kefir nearly lactose-free, which means that many people who can't tolerate milk, yogurt or other dairy products will be able to consume kefir without physical consequences. For individuals who don't use milk, non-dairy versions of kefir -- made with coconut milk, coconut water, rice milk and even fruit juices -- are available. However, these don't have the same amount of protein as milk-based kefir and have a somewhat different probiotic profile.

A number of health benefits are being attributed to the combination of probiotics, prebiotics and beneficial yeasts that kefir contains. In addition to supporting a healthy gut, studies have found that kefir, which contains upward of 30 different strains of bacteria and yeasts, has anti-inflammatory and anti-microbial properties. Other studies have suggested that kefir can boost immune response, and may even have anti-carcinogenic effects. It's important to note, however, that these are small studies with numerous caveats attached. Much more research is needed before making the leap from observation to medicinal claims.

If you do decide to work kefir into your diet, be sure to read the nutrition labels. The flavor of plain kefir ranges from tart to mouth-puckering. As a result, many brands add sugar, fruit and other flavorings to make it more palatable. Consider the fat, calories and carbohydrates you'll be adding to your daily total and adjust accordingly. And as with any food, don't go overboard. Add kefir to your diet gradually and see how you feel.

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