Effect of the Type and Proportion of Dietary Carbohydrate on Serum Glucose Levels and Liver and Muscle Glycogen Synthesis in the Rat

Abstract

The effect of the type of dietary carbohydrate on oral glucose tolerance and on in vivo incorporation of labeled glucose or fructose into liver and muscle glycogen in the rat were investigated. The intake of fructose or sucrose reduced, as compared with starch or glucose, glucose incorporation into liver glycogen and caused a slight deterioration of the glucose tolerance. These effects were observed already when 50% of the total dietary carbohydrate was substituted by fructose or sucrose. The incorporation of labeled glucose into muscle glycogen was not affected by the type of dietary carbohydrate. Specific radioactivity of liver and muscle glycogen and the concentration of muscle glycogen after administration of labeled fructose were higher in fructose-adapted than in glucose-adapted rats.