Passage of carbohydrate into the colon. Direct measurements in humans

Gastroenterology. 1983 Sep;85(3):589-95.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Biological Transport
  • Breath Tests
  • Colon / physiology*
  • Dietary Carbohydrates / metabolism*
  • Female
  • Gastrointestinal Motility
  • Hexosamines / metabolism
  • Humans
  • Hydrogen
  • Ileocecal Valve / physiology
  • Ileum / physiology
  • Intestinal Absorption
  • Lactulose / metabolism
  • Male
  • Middle Aged
  • Mucus / physiology
  • Starch / metabolism*
  • Sucrose / metabolism
  • Time Factors


  • Dietary Carbohydrates
  • Hexosamines
  • Lactulose
  • Sucrose
  • Hydrogen
  • Starch