Real kefir (not store-bought, which doesn't contain yeasts) is a super-food, with up to 40 different strains of yeasts & bacteria. Consider that I'm Greek, but I root for Kefir.

I read somewhere that a cup of yogurt contains up to 1 trillion bacteria, and kefir up to 5 trillion, I don't know if these numbers are correct though.

Real kefir (not store-bought, which doesn't contain yeasts) is a super-food, with up to 40 different strains of yeasts & bacteria. Consider that I'm Greek, but I root for Kefir.