Kombucha contains S Boulardii, so if you brew your own, you can have an endless supply. Much less expensive than pill form. And quite easy to make, and also delicious. Water kefir does not contain S Boulardii, even though some websites will say it does. I know because I react badly to S Boulardii pills (no other ingredients in the pill) and Kombucha, but am fine with water kefir.