When is dietary fiber considered a functional food?

Article type: Research Article

Authors: Leon Prosky,

Affiliations: L. Prosky Associates, Nutrition Consultants, 10265 Nolan Drive, Rockville, MD 20850-3507, USA. Tel.: +1 301 762 4421; Fax: +1 301 251 0485; E-mail: [email protected]

Abstract: Before answering the question of when dietary fiber can be considered a functional food we must first decide what can be called a dietary fiber. The generally accepted definition of dietary fiber is that of Trowell that dietary fiber consists of the remnants of edible plant cells polysaccharides, lignin, and associated substances resistant to (hydrolysis) digestion by the alimentary enzymes of humans. In Japan the food tables list the dietary fiber content of animal as well as plant tissues, while many countries accept saccharides of less than DP-10 as dietary fiber (inulin, oligofructose, Fibersol-2, polydextrose, fructooligosaccharides, galactooligosaccharides etc.). These shorter chain oligosaccharides do not precipitate as dietary fiber in the standard Association of Official Analytical Chemists (AOAC) method, which is accepted by the US Food & Drug Administration, the US Department of Agriculture and the Food & Agriculture Organization of the World Health Organization for nutrition labeling purposes. In the United Kingdom the term dietary fiber has been replaced in nutrition labeling by nonstarch polysaccharides. Therefore the American Association of Cereal Chemists (AACC) commissioned an ad hoc committee of scientists to evaluate continuing validity of the currently used definition, and if appropriate, to modify and update that definition. Obtaining scientific input from the community of analysts, health professionals, and dietary fiber researchers was considered a high priority. To this end three meetings were held in the space of six months to assure input from all persons knowledgeable in the field with the answer expected sometime before 2000. Dietary fiber can be considered a functional food when it imparts a special function to that food aside from the normal expected function and similarly when the dietary fiber is used as an additive to foods. For example, dietary fiber contributes to colonic health, bifidobacterial or lactobacillus stimulation in the gut, coronary artery health, cholesterol reduction, glucose metabolism, insulin response, blood lipids, cancer etc. The author discusses in detail the functional food properties of dietary fiber.

Keywords: total, soluble, insoluble dietary fiber, functional food claims

Journal: BioFactors, vol. 12, no. 1-4, pp. 289-297, 2000