Acidophilus is a friendly bacteria naturally found in the intestinal tract. More than 400 species of bacteria, also called normal flora, live in the adult human GI tract. Acidophilus is stomach-friendly and supports overall well-being.* Nature's Bounty probiotic acidophilus contains over 100 million active lactobacillus acidophilus at the time of manufacture. Adults can take one capsule daily, preferably with a meal.