The purest kind you can get, like from foods. Fermented vegetables, SauerKraut, Kim chi. But not grocery store brand, either organic from WholeFoods or make your own.
Or raw-organic yougurt, probiogurt and kefir.
I found out about this few days ago and havent tried it yet. If you do before me, please let me know.
Yes, In the beginning it seems overwhelming, takes some time to get used to it, then we start loving it :D when we know the benefits of our new lifestyle. You will never want to go back.