Control of jejunal sucrase and maltase activity by dietary sucrose or fructose in man. A model for the study of enzyme regulation in man.

The specific effect of dietary sugars on jejunal disaccharidase activity in seven normal nonfasted male volunteers was studied. The sugars tested were sucrose, maltose, lactose, glucose, fructose, and galactose. Comparisons were made of the effects of each sugar in an isocaloric liquid diet. In all subjects, sucrose feeding, as compared to glucose feeding, significantly increased jejunal sucrase (S) and maltase (M) activities, but not lactase (L) activity. The S/L and M/L ratios increased to a significant degree. Fructose feeding, in two subjects, gave results similar to sucrose when comparing fructose and glucose diets. One subject was fed lactose, galactose, and maltose. These sugars, compared to glucose, did not increase disaccharidase activity. Fructose appears to be the active principle in the sucrose molecule. These results demonstrate that specific dietary sugars can alter enzyme activity in the small intestine of man in a specific fashion. Sucrose and fructose are able to regulate sucrase and maltase activity. Dietary alteration of intestinal enzymes may represent a suitable system for studying the regulation of enzyme activity in man.