There are good and bad bacteria as far as our health goes. With 60 to 70 million Americans suffering from various digestive diseases, that means we need to pay attention to those little critters working 'round the clock inside of our bodies. Acidophilus, a common organism in yogurt and cultured milk products, such as kefir, that are said to foster a healthy balance of bacteria in the stomach. It's one of the "good" or "friendly" ones, out of about 400 types of bacterial that live in our intestinal tract and, for women, in the vagina as well. It's helpful because it aids manufacturing of B vitamins and production of lactase and other antibacterial agents.