I drink kefir daily and use it to make delicious smoothies, using my Juice Plus+ Complete (You can use soy milk, cow's milk, goat's milk, rice milk or coconut milk -- whichever you prefer. I like the taste of kefir).
Kefir is a tangy, slightly sour tasting fermented milk. Kefir's closest cousin is yogurt, also made by fermenting milk with bacteria. But kefir is fermented with more and different types of bacteria, in addition to yeast, which means the final product has more of the beneficial microorganisms, or "probiotics," that first made yogurt a popular health food. Probiotics can control the growth of harmful bacteria and aid digestion, and some even manufacture vitamins in the gut. Kefir can be made from any type of milk, cow, goat or sheep, coconut, rice or soy.
This is the brand of keifer I prefer - it is rich tasting and is a good source of protein, calcium, and pstassium. Other benefits of keifer are described here.