Passage of carbohydrate into the colon. Direct measurements in humans.
To quantify passage of unabsorbed dietary starch into the colon, 7 healthy volunteers had a multilumen tube positioned close to the ileocecal junction. Marker solution was perfused slowly, 20-40 cm above an aspiration site, to estimate, by marker dilution, flow through the ileum. On consecutive days, subjects ate liquidized meals containing 20 or 60 g starch; ileal aspirates were analyzed for starch and glucose for 5-6 h fasting and 4-7 h postprandially. Volume and carbohydrate concentrations were used to derive total carbohydrate traversing the ileum. In different subjects, unabsorbed carbohydrate was 453-4023 mg (2.3%-20.1%, mean 9.3%) for the smaller meal and 1332-6352 mg (2.2%-10.4%, mean 6.0%) for the larger. In 4 volunteers, hydrogen breath tests were performed on separate occasions after sucrose (50 g), lactulose (26 g), and the 20-g meal. Lactulose increased hydrogen excretion; sucrose and the test meal did not. We conclude that 2%-20% of dietary starch escapes absorption in the small bowel, confirming others' results using breath tests alone. Breath tests, though more convenient than intubation studies, may be a less sensitive index of starch malabsorption.
D000328:Adult; D000368:Aged; D001692:Biological Transport; D001944:Breath Tests; D003106:Colon / Q000502:physiology*; D004040:Dietary Carbohydrates / Q000378:metabolism*; D005260:Female; D005769:Gastrointestinal Motility; D006595:Hexosamines / Q000378:metabolism; D006801:Humans; D006859:Hydrogen; D007080:Ileocecal Valve / Q000502:physiology; D007082:Ileum / Q000502:physiology; D007408:Intestinal Absorption; D007792:Lactulose / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009093:Mucus / Q000502:physiology; D013213:Starch / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D013997:Time Factors
D004040:Dietary Carbohydrates; D006595:Hexosamines; D007792:Lactulose; D013395:Sucrose; D006859:Hydrogen; D013213:Starch