dvjorge,
I thought S. Boulardi was one of the ingredients of Threelac. I just checked the Threelac label again and it only lists "dry yeast powder" as an ingredient.
I take Threelac in the daytime and S. Boulardi at night.
I make my own yogurt whey and use it to make cultured drinks and vegetables. I can't tolerate kefir or most multi-strain probiotics (like Dr. Ohiras) for example. If I could get myself healthy enough to eat kefir I would consider it a major breakthrough.