The effect of poorly absorbed solute on intestinal absorption

Scand J Gastroenterol. 1990 Dec;25(12):1257-64. doi: 10.3109/00365529008998562.


To determine the effects of poorly absorbed solute on intestinal absorption, the urinary recovery of ingested lactulose, L-rhamnose, D-xylose, and 3-O-methyl-D-glucose was measured after simultaneous ingestion of various 'loads' of mannitol given in iso-osmolar solution. Mannitol reduced intestinal uptake of the poorly absorbed test sugars, lactulose and L-rhamnose; uptake of D-xylose and 3-O-methyl-D-glucose, which are absorbed by carrier-mediated transport largely from the jejunum, was less affected. The dose-response effect of mannitol on the absorption of L-rhamnose was approximately exponential; doses of 5, 10, and 20 g mannitol reduced the average urinary excretion of L-rhamnose by 34.7%, 51.7%, and 61.2%, respectively. In this respect, an osmotically equivalent load of lactulose, ingested as 'solute', was approximately twice as effective as mannitol in reducing L-rhamnose absorption, probably because lactulose is more poorly absorbed than mannitol (less than 1.0% versus 32-41%). Ingestion of other poorly absorbed solutes such as raffinose, sorbitol, xylitol, magnesium sulphate, and sodium sulphate also significantly depressed the absorption of L-rhamnose; in contrast, more efficiently absorbed solutes, such as sodium chloride, glucose, glycerol, and urea had little effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-O-Methylglucose
  • Adult
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Intestinal Absorption / drug effects*
  • Lactulose / administration & dosage
  • Lactulose / metabolism
  • Lactulose / pharmacology*
  • Male
  • Mannitol / administration & dosage
  • Mannitol / pharmacology*
  • Methylglucosides / metabolism
  • Middle Aged
  • Rhamnose / metabolism
  • Solubility
  • Xylose / metabolism


  • Methylglucosides
  • 3-O-Methylglucose
  • Mannitol
  • Lactulose
  • Xylose
  • Rhamnose