The plain variety is the healthiest as it does not have flavor additives. From Dr. Weil " The one caution I would give you is that commercial kefir often is overly sweetened and full of additives. Read labels carefully. I would buy plain varieties and add your own sweetener and flavoring if you like. And making your own kefir isn't difficult, with starter kits widely available. You'll have to experiment a bit to produce kefir that bests suits your taste. In general, the longer the fermentation time, the more sour the finished product. Enjoy!" http://www.drweil.com/drw/u/id/QAA400018
"Kefir is a cultured, creamy product with amazing health attributes. Kefir's tart and refreshing flavor is similar to a drinking-style yogurt, but it contains beneficial yeast as well as friendly 'probiotic' bacteria found in yogurt. The naturally occurring bacteria and yeast in kefir combine symbiotically to give superior health benefits when consumed regularly. It is loaded with valuable vitamins and minerals and contains easily digestible complete proteins."
Where to get Kefir?
Recipes that use Kefir: