World Digestive Health Day WDHD – May 29, 2016 RECOMMENDATION FOR INTAKE, AND ROLE IN DISEASE PREVENTION AND MANAGEMENT NEVIN ORUC, MD, PHD Ege University, Faculty of Medicine Gastroenterology Department Bornova, Izmir, Turkey Dietary fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption by the human intestine. Dietary fiber includes polysaccharides, oligosaccharides, lignin, and associated plant substances. The sources of fiber vary in chemical and physiological properties.1,2 “Dietary fiber” was first used in the literature in 1953 by Hipsley, who used the term to refer to celluloses, hemicelluloses, and lignin.3 Since then, the definition has undergone many revisions. According to Codex Alimentarius, dietary fiber is defined as carbohydrate polymers with 10 or more monomeric units, which are not hydrolyzed by the endogenous enzymes in the small intestine of humans. The decision to include carbohydrates from three to nine monomeric units was left to national authorities.4 Several authorities from Canada, Australia, New Zealand, and the European Union considered carbohydrates with three to nine monomeric units as a part of dietary fiber definition. The definition has been expanded to include oligosaccharides, such as inulin and resistant starches. A universal definition, or consistency among definitions, is necessary for food labels and for research purposes. There are several different classification systems for dietary fiber. Classifications of components of dietary fiber are based on their gastrointestinal solubility, site of digestion, products of digestion, or physiological properties.1 Most common fiber classification categories include water-insoluble/less fermented fibers (cellulose, hemicellulose, lignin) and the watersoluble/ well fermented fibers (pectin, gums, and mucilages).5 Physiological effects of fiber differ from one non-digestible carbohydrate to another. The same amount from different sources of fiber does not really infer the same levels of impact on health. There are many different forms of fiber in food and there is also a wide range of foods delivering fiber. Dietary fibers can be extracted from edible material (intrinsic) or modified and added back into a food (extrinsic).6 Dietary fiber supplements have the potential to play an adjunctive role in offering the health benefits provided by high-fiber foods. DIETARY FIBER; DEFINITION, Current recommendations for dietary fiber intake are related to age, gender, and energy intake; and the general recommendation for adequate intake is 14 g/1000 kcal.2 This average intake includes non-starch polysaccharides, analogous carbohydrates, lignin, and associated substances.2 Using the energy guideline of 2000 kcal/day for women and 2600 kcal/ day for men, the recommended daily dietary fiber intake is 28 g/day for adult women and 36 g/day for adult men. The Institute of Medicine in the USA recommended intakes of 30 g dietary fiber daily for adults based on protective effects against cardiovascular disease.7 Other organizations followed suit, recommending an intake of at least 25 g dietary fiber daily for the general population. Most people, however, under consume dietary fiber, and usual intake averages only 15 g per day.8 Dietary fiber intake provides many health benefits. A generous intake of dietary fiber reduces risk for developing various diseases, including coronary heart disease, stroke, hypertension, diabetes, obesity, and certain gastrointestinal (GI) disorders. Increased consumption of dietary fiber improves serum lipid concentrations, lowers blood pressure, improves blood glucose control in diabetes, aids in weight loss, and appears to improve immune function.9 High dietary fiber intake may reduce the risk of total mortality (See Table 1). INCREASED FECAL BULK/LAXATION Solubility, viscosity, and water holding properties of fiber affect digestion and the absorption function of the GI tract. High insoluble fiber intake increases fecal bulk and decreases Table 1: Beneficial effects of dietary fiber in disease prevention and management • Increased laxation • Decreased colonic transit time • Increased colonic fermentation/short chain fatty acid production • Positive modulation of colonic microflora • Beneficial effect on mineral absorption • A protective role in the prevention of colon cancer and other malignancies • Improvement in immune function. • Reduced total and/or LDL serum cholesterol levels • Attenuation of postprandial glycaemia/insulinaemia • Reduced blood pressure • Weight loss, Increased satiety • Decreased mortality 12 WGO Handbook on DIET AND THE GUT World Digestive Health Day WDHD May 29, 2016
WGO Handbook on Diet and the Gut_2016_Final
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