Modification of Intestinal Absorption by Dietary Fiber and Fiber Components

Abstract

Some types of dietary fiber have been shown to reduce the magnitude of hyperglycemia and insulinemia after carbohydrate-containing meals in normal man (Jenkins et al., 1977a) and diabetic man (Jenkins et al., 1976). This effect is not confined to the viscous polysaccharides studied by Jenkins et al. (1976, 1977a); wheat bran has been shown to have a similar though smaller effect (Jeffreys 1974; Jenkins et al., 1978). Subsequent studies, which have been of two types, have suggested a possible therapeutic role for dietary fiber in the management of diabetes. There have been those in which one form of dietary fiber has been added to several food items in an otherwise low-fiber diet and those in which two diets, one high-fiber and one low-fiber, are compared. Studies of the latter type have in some cases inevitably involved comparison of high-fiber, high-carbohydrate diets with low-fiber, “low”-carbohydrate diets, so that the relative roles of fiber and proportion of energy from carbohydrate are difficult to assess, although the combined effect on diabetic control seems to be an improvement (Simpson et al., 1979a,b). Rivellese (1980) compared low-and high-fiber diets of similar carbohydrate content in diabetic patients and concluded that dietary fiber improved blood glucose control, and Miranda and Horwitz (1978), using low- and high-fiber diets, although with slightly less available carbohydrate in the high-fiber diet (Anderson 1980), demonstrated lower post?prandial blood glucose levels in diabetic patients on the high-fiber diets. Others, however, have found high-fiber diets unsatisfactory (Manhire et al., 1981), and the value of dietary fiber has been called into question (Anon, 1981) but stoutly defended (Mann et al., 1981).