Definition of Prebiotic

A prebiotic is defined as a nondigestible food ingredient that is used as an energy source by beneficial bacteria found naturally in the body's intestines. According to the Harvard Medical School, any dietary component that reaches the colon intact is a potential prebiotic; however, much of the interest in prebiotics is focused on nondigestible fibers found in plants, mainly oligosaccharides such as inulin-type fructooligosaccharides (FOS) and trans-galactooligosaccharides (TOS). These fibers are fermented in the colon, where they are thought to increase the population of potentially health-promoting bacteria while reducing the number of harmful bacteria.

Health Benefits

Some of the proposed benefits of prebiotics are controversial and require more research. However, preliminary evidence shows that prebiotics may assist in reducing irritable bowel problems, boosting the immune system, normalizing bowel function and improving a host of ailments such as antibiotic-associated diarrhea, traveler's diarrhea, gastroenteritis and colitis. In a 2005 article published in the "British Journal of Nutrition," the authors state a large number of animal studies suggest inulin-type fructans enhance calcium and magnesium absorption, decrease triglycerides and reduce the risk of colon carcinogenesis.

Food Sources

Prebiotics can be found naturally in a variety of foods, such as artichokes, barley, bananas, berries, chicory, flax, garlic, greens, honey, leeks, legumes, onions, dairy products, whole grains, soy beans and soy products.

Other Sources

Prebiotics are also added to some processed foods, such as drink mixes, meal replacement items, cereals and yogurt. Prebiotics have also been added to some pet and farm animal foods. Prebiotics can be identified on labels or through the manufacturer's website; however, not all foods with naturally occurring prebiotics are labeled.

Synbiotics

Synbiotics are the combination of probiotics, the live bacteria, and prebiotics, the energy source for the bacteria. Synbiotics are thought to provide dual benefits and enhance probiotic survival and implantation. Probiotics, coupled with a food source, have a better chance to survive in the digestive system, where alone, they often do not live due to oxygen, low pH, temperature and competition with other bacteria. Synbiotics can be found in some foods, such as fermented dairy products, like yogurt and kefir, or in supplement form.

Dosing

Currently there are no specific guidelines for prebiotic dosage. The Mayo Clinic states some studies suggest consuming 3 to 8 g daily to receive full health benefits.