Intestinal Absorption of Sucrose in Man: The Site of Hydrolysis and Absorption*

Abstract

The site of intestinal absorption of the disaccharide sucrose is studied in normal man by the use of both an oral meal and an infusion technique. Both hydrolysis and absorption are quite efficient in human jejunum. Furthermore sucrose absorption rates are considerably more rapid in jejunal segments than in ileal segments (p < 0.001). Absorption appeared to be less than hydrolysis at ileal as compared to jejunal segments. This suggests that a difference in surface area alone cannot account for the greater absorption rates in jejunum. During sucrose absorption, appreciable amounts of glucose and fructose appeared in the intestinal lumen. The amounts of the monosaccharide products of sucrose hydrolysis that accumulated could not be explained by intraluminal sucrase activity. These findings suggest that considerable amounts of glucose and fructose are released from sucrose hydrolyzed by mucosabound enzyme and that these monosaccharides moved from the mucosal surface to the lumen to be absorbed.