Probiotics as functional foods.

Probiotic products have been widely used in Japan and Europe for years. Probiotics are now emerging as an important category of food supplement in the United States. Questions about the biologic nature, available products, claimed health benefits, and safety and regulation of probiotics are important for both consumers and nutrition professionals. Probiotics can be considered functional foods because they provide health benefits beyond the traditional nutrition function. With few exceptions, most probiotic products currently available contain lactic-acid-producing bacteria, which mainly belong to the genera Lactobacillus and Bifidobacterium. We reviewed the scientific papers published in major nutrition journals and abstracts available on the PubMed website regarding probiotics. Evidence suggests the following beneficial effects of probiotics: normalization of the intestinal microflora, ability to block the invasion of potential pathogens in the gut, prophylactic or therapeutic treatment for several types of diarrhea, relief of symptoms of irritable bowel syndrome and inflammatory bowel disease, amelioration of lactose intolerance, prevention of colon cancer, modulation of immune function, inhibition of Helicobacter pylori, and possible enhancement of calcium absorption and reduction of blood cholesterol levels. Mechanisms for the above benefits have been proposed, but none has been proven. An adequate level of viable bacteria in a probiotic product and an appropriate daily dose are critical to achieve a health benefit. Because probiotics are not known to be pathogenic and their upper tolerable level is high, they could be promoted as a beneficial food supplement. Currently, no disease-prevention or therapeutic claim for probiotics is legally allowed.