Promises and problems of functional foods.

"Functional" foods are branded foods, which claim, explicitly or implicitly, to improve health or well being. We review typical functional foods and their ingredients, efficacy, and safety. We also review regulations for health claims for foods worldwide. These regulations often allow manufacturers to imply that a food promotes health without providing proper scientific evidence. At the same time, regulations may ban claims that a food prevents disease, even when it does. We offer a plea for regulations that will permit all health claims that are supported by the totality of scientific evidence, and ban all claims that suggest an unproven benefit.