kefir is actually just very thin yogurt. If you make your own yogurt at home and use just milk and culture, it comes out pretty thin. I just looked in my Whole Foods Encyclopedia Book and it says that you can get kefir culture at health food stores.
Here are instructions from Rodales natural foods cookbook. It is made like yogurt, heat milk and then cool to comfortable warm temp. Add culture (or yogurt or kefir with live cultures), and incubate in warm place for 12 to 24 hours).
Most storebough kefirs are heavily sweetened, I've found.
I'd love to have a yogurt maker. I'd like to try both kefir and yogurt. I find alot of things too sweet for my liking. The only time in my life when I could eat practically anything including quite sweet-tasting foods was for the first couple of months after a cesarean five y. ago and then two years ago for the first few months when I first began tandem nursing.
There are some who swear by kefir every day. Who claim it is a superior probiotic. But then I see there are various ways of starting a "real" culture. I wonder which method JW uses.