Updated August 16, 2016

Both dietary fibers and prebiotics are fermented in the colon and alter the composition and/or activity of the gut microbiota. Dietary fibers exhibit a diverse range of physiological effects including improved laxation, benefits on risk factors for cardiovascular disease, weight management, immune function, and colonic health (Slavin 2013; Brownawell and others 2012). Prebiotics was first defined as “nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, thus improving host health” (Gibson and Roberfroid 1995).  This definition was later refined to include other areas that may benefit from selective targeting of particular microorganisms “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora, that confer benefits” (Gibson and others 2004). The potential beneficial effects of prebiotics on the gut microflora has generated intense scientific, consumer, and regulatory debate since the mid-1990s.

Prebiotics occur naturally in foods such as leeks, asparagus, chicory, Jerusalem artichokes, garlic, onions, wheat, oats, and soybeans. To date, all known prebiotics are carbohydrate compounds, primarily oligosaccharides, which resist digestion in the human small intestine and are fermented by the gut microflora in the colon. Studies have shown that inulin and oligofructose, lactulose, and resistant starch meet all the criteria of the definition of prebiotics. Other isolated carbohydrates and carbohydrate-containing foods, including galactooligosaccharides, trans-galactooligosaccharides, polydextrose, wheat dextrin, acacia gum, psyllium, banana, whole grain wheat, and whole grain corn also have prebiotic effects. For a food ingredient to be classified as a prebiotic requires scientific demonstration that the ingredient: 1) resists gastric acidity, hydrolysis by mammalian enzymes, and absorption in the upper gastrointestinal tract; 2) is fermented by the intestinal microflora; and 3) selectively stimulates the growth and/or activity of intestinal bacteria potentially associated with health and well-being (Slavin 2013; Brownawell and others 2012).

The data on the health outcomes of prebiotics are not as extensive as the evidence on dietary fiber, however, studies have shown that the intake of prebiotics may: decrease the risk and severity of gastrointestinal infection and inflammation including diarrhea, inflammatory bowel disease and other gastrointestinal disorders; have protective effects to prevent colon cancer; increase the bioavailability and uptake of minerals (such as calcium, magnesium, and possibly iron); lower some risk factors for cardiovascular disease; and promote satiety and weight loss. Prebiotics when added to foods can be considered a functional food ingredient (Slavin 2013; Brownawell and others 2012).

The web-based content on prebiotics is intended to educate and engage food scientists, dietitians, nutritionists, regulatory, scientific, and consumer stakeholders on the role of prebiotics in foods and in human health.  Our aim is to elevate the role of food science and technological innovations in formulating foods with prebiotics (natural sources, isolated or commercially prepared). Complete citation of the references mentioned above is available in the section on “Publications on Prebiotics.” Please contact Farida Mohamedshah at 202-330-4986 or, should you have questions regarding the content of this webpage.

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