Nature's Way Primadophilus Reuteri Pearls Probiotic, Supports Digestion and Immunity, Survives Stomach Acid, 60 Softgels. What is Reuteri? Pronounced roy'-tur-eye, this unique lactobacillus is naturally found in human breast milk, and is one of the first defenses a nursing mother passes to her child. When taken as a supplement, reuteri colonizes in the intestine and provides healthy benefits.* Why take Primadophilus® Reuteri? Maintaining a proper level of Lactobacillus reuteri SD-5865 and other Lactobacillus & Bifidobacterium cultures in the intestinal tract can: help support healthy immune function*, and promote healthy digestion.* No refrigeration required!