probiotic

probiotic A substance that appears to replenish or support the growth of helpful bacteria in the intestinal tract. The most common probiotic is acidophilus, which is present in yogurt, in acidophilus milk, and in supplements. As the name indicates, probiotics have been developed to counter one unfortunate effect of treatment with antibiotics: the decimation of helpful intestinal bacteria along with disease-causing bacteria. See also acidophilus.