NOW FOODS PROBIOTIC -10 25 BILLION is a balanced spectrum of live organisms consisting of acid-resistant probiotic bacterial strains that are known to naturally colonize the human GI tract. Probiotic bacteria are critical for healthy digestion, help maintain the integrity of the intestinal lining, support proper intestinal motility and participate in the detoxification process. Probiotic-10™ utilizes bacterial strains that have been clinically validated for their support for their immune system function.