Introducing our highest potency probiotic. UP4 Ultra has 50 billion cultures in every serving of seven exceptionally robust strains, specifically selected for acid and bile resistance and ability to colonize the gut. As always, we start with our ultimate superstrain, L. acidophilus DDS®-1. To this we have added Lactobacillus strains (L. plantarum and L. salivarius) for small intestine support along with our signature combination of four Bifidobacteria strains (B. longum, B. lactis, B. bifidum and B. lactis HN019) for the large intestine.