Prebiotics are nondigestible carbohydrates that feed beneficial bacteria living in intestines. High levels of the food components allow friendly bacteria to flourish along the intestinal tract. A prebiotic occurs naturally and is found in many foods, especially high-fiber fare. While touted as paramount for good digestive health and as a possible cure for digestive ailments, some doctors have cast doubt on the effectiveness of prebiotics. The term prebiotic should not be confused with a probiotic, which is a bacterium that aids the host’s digestion.
Glenn Gibson, a professor of food microbiology, and Marcel Roberfroid, a biochemist, introduced the idea of a prebiotic in a 1995 Journal of Nutrition article. The scientists found that prebiotics in the intestinal tract prompted specific bacteria growth and changed the composition of the microorganisms in a digestion system. Gibson and Roberfriod’s research indicates that heightened presence of prebiotics regulates lipid metabolism, a process that could help control cholesterol levels.
When the these substances enter the body, they land along the digestive tract. There they selectively feed only certain types of microorganisms present in the body. The friendly bacteria feeding from the prebiotics in turn may aid digestion. Prebiotics selectivity — i.e., targeting beneficial bacteria only — sets the substance apart from dietary fiber, which performs similar tasks in the intestines.
A prebiotic enters the body through food consumption and is not broken down by either the cooking process or digestion. High-fiber foods contain especially high levels of prebiotics, which is why the substance also is known as fermentable fiber. Fermentable fiber is found in high levels in whole grains, such as wheat, barley and oatmeal. It is also found in vegetables and fruits, including artichokes, onions, berries and bananas, honey, and dairy products.
Others choose to introduce a prebiotic through supplements or as an added ingredient in processed foods. Supplements in gummy chewable forms and powders are available through natural food distributors and vitamin sellers. People interested in ingesting additional fermentable fiber also should read food labels; some manufacturers add it to items such as yogurt or energy bars.
Advocates of a prebiotic-heavy diet tout the benefits of its role in digestion. Natural medicine practitioners have prescribed prebiotic foods to address ailments ranging from diarrhea and irritable bowel syndrome to an inflamed colon. Some also have suggested that a focus on prebiotic foods could relieve Crohn’s disease. Additionally, supporters say it may improve digestion, calcium absorption, and immunity in already healthy people.
Detractors, however, point to the paucity of research done on the diet’s effects. They note that no recommended daily amount of prebiotics has ever been set. There also is no firm research indicating the the substance provides any true benefit to digestion.