It is a cultured milk product much like yogurt - some call it the mother of yogurt.
You need kefir grains to put in the milk to grow. They call them grains but they are clumps of living enzymes that reproduce quickly and change the milk much the same way yogurt is made - the lactose in milk is changed over to lactic acid.
My kids love it for fruit smoothies. We grow our grains using fresh raw cow and goat milk.
I use Kefir myself. I learned about it from a friend from Russia. I used to make it with the store bought Kefir. But then another friend of mine gave me some real Kefir grains...the difference was night and day. I suspect that the commercial kefir is merely something that someone has tried to do with foreign strains of a handful of the microflora strains. If you want to make some really wonderful sour cream. This is what I do. I take a mason jar, and pour a quart of heavy cream in it. Then I add a tablespoon or two of kefir into the cream.Shake it to thoroughly mix. Do not screw the lid on tight as it will build pressure. I let it sit out at room temperature for 24 to 36 hours. Then put it in the fridge, and get good and cold. It may take 2 or 3 days to get good and thick (in the fridge). The kefir from the store works very well for this. You will have the best sour cream you have ever put into your pie hole!!!
And kefir is wonderful. Read the wonderful things about it on the internet. From what I have read about raw milk, humans got many of these benefits from fresh milk (unpastuerized). But in my opinion, the powers that be, want you to get your healing from a pill. Interesting factoid. There is a patent pending on this. If someone is sick from an infectuous disease, You can take blood from the patient, inject it into the udder of a mammal, and the raw milk will contain an all natural "anti-biotic". I repeat, this is a patented process.! Go figure............
We were just introduced Kefir about 3 weeks ago. We are using store bought now but Sharon has some Kefir grains coming so we can make the "real deal"
Anyway - I am one to laugh and say there is no way stuff like that works. BUT I'm here to say there is something to it. I don't know the what's and why's but I have more energy and just overall feel better so it's doing something good.
If you want to make your own Kefir as well as many other types of milk products (yogurt, sour cream, buttermilk, etc.) go thttp://www.cheesemaking.com/store/p/171-Gourmet-Home-Dairy-Kit.html and look at this site! I make most of our cheese, yogurt, butter, etc. I have bought a couple of the kits (Mozerella kit and Gourmet Home Dairy Kit with Yogotherm) from this site and they all turn out fantastic and the folks are wonderful with customer service online and live!
We drink kefir most every day (though I blend it in to smoothies rather than drink it plain, too sour for my taste) and I swear it makes the best smoothies ever! The grains are easy to work with and quite forgiving--I often take a **break** and store them in the fridge in milk or water and then pick right back up with it when I get a taste for it again.
2 cups kefir
1 frozen very-ripe banana
1 cup frozen blueberries
about a cup of crushed ice
I blend it all up in my VitaMix and then I fight the kids off while I try to drink my share
. The over-ripe banana sweetens everything up so that I don*t have to add sugar/honey/sweetener. Funny thing is, I normally hate bananas in smoothies, but something about the kefir totally masks the flavor so that it is all just yummy goodness!
I also use a bit kefir to soak my grains and beans. When I over-brew a batch I just dish it up for the chickens--it is their favorite teat.