Re: starter Kefir isn't heat sensitive?

 So you can have dry powdered kefir starter mailed without a problem?

I get the kefir already made. I use it in place of yogurt as a snack once in a while, or take larger doses if my stomach is upset.

I suppose it lasts a long time dry, and then you add it to any form of milk?

They should be pretty stable in a dry form.

The prebiotic you recommind is FOS?

Yes, fructooligosaccharides. These are long chain sugar molecules (fiber) that feed the flora. It is a fine off white powder that has virtually no taste. So it can be easily added to foods.

What does a prebiotic do that's better than kefir? 

Any probiotic will only replace a limited number of bacterial strains. They do not replace all of the various strains of bacteria in the intestines. Prebiotics on the other hand feed the flora, so they will stimulate the growth of all the flora in the intestines. Even if someone takes antibiotics they will never kill off every last beneficial bacteria of a particular strain. So these surviving bacteria can be stimulated to increase in numbers by feeding them. Therefore I look at probiotics as a jump start to getting the flora up, but use prebiotics to keep up the growth for the long run.