Kefir is a cultured dairy product similar to a yogurt drink that originated in the Caucasus Mountains straddling Europe and Asia. Its promoters call it “miracle milk” because of its alleged health benefits.
Traditionally, kefir is made by fermenting milk with kefir “grains”—a mixture of bacteria and yeast bound in a gelatinous matrix. The result is tangy like yogurt, but it may also be slightly alcoholic and fizzy, depending on the fermentation time and technique. For safety and consistency, most commercial kefirs use powdered starter cultures instead of the grains. In contrast, yogurt is typically fermented with different strains of bacteria, not with yeast.
Like yogurt, kefir contains probiotic bacteria. Probiotics may reduce antibiotic-associated diarrhea and help in some other intestinal conditions. Because kefir has more strains of beneficial bacteria than yogurt, it may have a wider range of effects. But despite the claims, there’s no good evidence that kefir—or any probiotic—lowers cholesterol or blood pressure, increases energy, strengthens nails and hair or prevents cancer and diabetes.
Kefir is rich in protein, calcium, B vitamins and other nutrients. Choose low-fat or nonfat varieties. Kefir made from soy milk is also available. Traditional kefir is not sweet, but most commercial products have added sugar, along with fruit (or fruit flavors). Commercial brands contain no alcohol.