Fiber, Obesity, and Diabetes

Abstract

Cleave and Campbell (1966) and Trowell (1974, 1975) have suggested that consumption of fiber-depleted foods plays an important role in the etiology of diabetes. Trowell advanced the argument that the incidence of diabetes in England and Wales could be correlated with the fiber content of flour. He also cited examples of populations (South African Bantu, Yemenite Jews) whose incidence of diabetes increased soon after changing from a high-fiber diet to a low-fiber diet. Jenkins et al. (1976, 1977) showed that meals rich in fiber reduced hyperglycemia and improved glucose tolerance in human subjects: Their findings were confirmed in other laboratories (Miranda and Horwitz, 1978; Monmer et al.,1978). Anderson and his colleagues (Anderson, 1980; Anderson and Ward, 1978; Kiehm et al., 1976) have devised a high-carbohydrate, high-fiber diet which contains the same number of calories as the diet recommended by the American Diabetes Association but in which the percentage of calories from carbohydrates is increased from 43 to 70. The increase in carbohydrate is principally in the form of complex carbohydrate. A comparison of the representative diets is shown in Table I. This type of diet reduces serum cholesterol and blood glucose and permits reductions in dosages of insulin or oral hypoglycemic agents needed for control of diabetes. Stone and Connor (1963) fed a similar diet to diabetics that also proved to be hypolipidemic. These diets act by inhibiting glucose absorption and thus reduce serum insulin response. Plasma glucagon levels are also lower in diabetic subjects ingesting a high-fiber diet (Miranda and Horwitz, 1978). Excellent reviews on the effect of fiber on carbohydrate metabolism (Jenkins, 1980) and diabetes (Anderson, 1980) have appeared recently.