Source Naturals Bifidyn is an advanced and potent bifidus product. It contains two complementary forms of bifidus. Bifidobacterium longum is an acid-stable and viable strain of bifidus for successful implantation into digestive tracts. Bifidobacterium bifidum is naturally found at high levels in mothers' breast milk, and is a predominant flora in healthy infants' colons. Bifidus supports human colon health by altering the intestinal ecology to favor "friendly" flora. Bifidyn's cells are specially protected before and after freeze-drying by a unique stabilizing process.