L. bulgaricus is intended to help the Gi tract be more suitable for the survival and growth of L. acidophilus and B. bifidum. L. acidophilus is the primary bacteria of the small intestine while B. bifidum is the major bacteria of the large intestine. The strains of L. acidophilus and B. bifidum used in this product have been the subject of in-vitro tests to help ensure they are more likely to be implantable, attaching themselves to the intestinal wall and becoming part of the naturally occurring flora.