Kefir: A Tangy Probiotic Beverage A glass of kefir being poured. Kefir is a cultured, fermented milk drink originally from the Caucasus Mountains of Eurasia. It has a tangy, slightly sour taste and a gentle fizziness from fermentation. In texture it’s like a thin, drinkable yogurt – usually made from cow, goat, or sheep’s milk. People add “kefir grains” (gelatinous clusters of bacteria and yeast) to milk and let it sit at room temperature; the microbes in the grains turn the milk sugar (lactose) into lactic acid, tiny bubbles of carbon dioxide, and a trace of alcohol. The result is a nutritious dairy beverage rich in protein, calcium and B vitamins, loaded with live probiotic organisms (beneficial bacteria and yeasts) that help maintain healthy gut flora. Today kefir is enjoyed worldwide – plain or flavored – and comes in many varieties (even non-dairy versions made with water or juice). Origins and Traditional Use Kefir has a long history as a health-promoting folk food. It l...