Intestinal Absorption of Sucrose in Man: the Site of Hydrolysis and Absorption.

Sucrose, unlike the other common disaccharides, maltose and lactose, has been reported to be absorbed poorly from jejunum in man. Using a single-lumen tube technique and giving a carbohydrate-protein-fat meal with a single disaccharide as the source of carbohydrate, Dahlqvist and Borgstr6m (1) reported efficient absorption of lactose and maltose from human jejunum but minimal absorption of sucrose. They assumed that sucrose must have been absorbed in lower jejunum and ileum, but no ileal studies were performed. This apparent difference in the site of absorption of sucrose as compared to maltose and lactose has been quoted as fact (2, 3), and, if true, might serve to distinguish jejunal and ileal malabsorptive disease in man on the basis of comparative blood sugar curves after ingestion of the different disaccharides. Dahlqvist (4) subsequently reported data demonstrating maximal activity in human jejunum for the sucrose splitting enzyme, sucrase, but he did not relate this information to the site of hydrolysis and absorption of sucrose. In addition, recent extensive disaccharidase determinations on human intestinal mucosa by Auricchio and co-workers (5) have demonstrated activity of sucrase in jejunal and ileal mucosa to be similar, a finding that would not be expected if sucrose were hydrolyzed and absorbed principally in ileum.