Live bacteria that are either the same as or similar to microorganisms found naturally in the human body that are beneficial to health. Human digestive systems normally have what we would call "good" bacteria and "bad" bacteria. Maintaining the correct balance between the "good" bacteria and the "bad" bacteria is necessary for optimal health. Things like medications, diet, diseases, age, and the environment can upset that balance. Probiotics are available to consumers in dietary supplements, yogurts, and other drinkable products typically found in refrigeration.