Think of kefir as milk meets yogurt with a shot of fizz. It's made by adding a special kefir culture, nubby little "grains" like those pictured above, to a batch of milk. Those grains contain a mix of beneficial bacteria and some yeasts, similar to the scoby used to make kombucha. Within a day or two, the grains ferment the milk into pleasantly tangy and effervescent drink.
This is considered a healthful probiotic beverage that helps balance the flora and fauna in our bodies. It's also been said to help digestion, bolster the immune system, and aid in reducing blood pressure. Whether or not you believe these health benefits, kefir certainly contains a good dose of calcium, various amino acids, and vitamins A and D.
Kefir might be new to you, but also like kombucha, it's a drink with a very long history. According to Anne Mendelson, author of Milk, it was originally a way of preserving fresh milk in the days before refrigeration and was drunk throughout the Caucacus region in eastern Europe. It's still a popular beverage in Russia.
And kefir doesn't have to be made with strictly with cow milk! Goat milk can be used, as well as non-dairy milks like almond milk and soy milk. Another strain of "water kefir" grains can also be used to make kefir from coconut water, fruit juice, or even simple sugar water.
What's more, it's easy to make yourself once you get your hands on some kefir grains. The grains are self-propagating, so your initial batch will last you as long as you continue to make kefir. Here are a few sources:
What do you think of this beverage?