SUMMARY The effect of high methoxy apple pectin, a carbohydrate gelling agent, on the intestinal absorption of glucose, water, and sodium was studied in man. The effect of intraluminal fibre was evaluated in 22 healthy volunteers by the intestinal perfusion technique under an occlusive balloon. The test solutions (NaCl 130 mM, KCI 5 mM, glucose or mannitol 30 mM, PEG 4000 5 g/l) were perfused just beyond the ligament of Treitz at a rate of 10 ml/min. A 25 cm segment was studied. Three concentrations of pectin were tested: 6, 10, and 15 g/l. The effect of this pectin at two concentrations, 6 and 10 gIl, on the jejunal unstirred layer thickness was evaluated in nine other healthy subjects by an electrical technique. In mannitol solution, pectin reversed water and sodium absorption, whatever its concentration was, while in glucose solution it significantly reduced absorption of water and sodium at 10 and 15 g/l only (p<001). It significantly reduced glucose absorption at all concentrations (p<001). This reduction was found to be correlated with the solution viscosity (p<0.01). Pectin did not alter the glucose dependent sodium transport but increased significantly (p<0.001) the unstirred layer thickness. These results suggested that, in healthy man, pectin acutely given may impair intestinal absorption by means of an increased unstirred layer resistance. This effect could contribute to the diminished postprandial glycaemia observed in human subjects fed pectin. Different 18 November 1983 intestinal glucose absorption is yet unknown. Holt et a17 have shown, in an acute study, that relatively large doses of guar gum (16 g/meal) and pectin (10 g/meal), in 400 ml orange juice containing ll3mIn-diethylene triamine penta-acetic acid as a nonabsorbable marker, markedly reduce the rate of gastric emptying in normal man, suggesting that this alteration in emptying may account for the reduction of glucose absorption. Moreover, chronic pectin supplementation (20 g/day/4 weeks) markedly slows gastric emptying of a 100 g carbohydrate solid meal surface-labelled with 9mTechnetium sulphur colloid in normal volunteers.8 9 The direct effect of gel fibres on intestinal glucose absorption has not been shown so far in man and experiments in rats gave conflicting results: in in vitro investigation using everted sacs of rat jejunum, carbohydrate gelling agents were found to reduce intestinal glucose absorption. This inhibition was correlated with the incubation medium viscosity which is a function of the polysaccharide concentration alone10 and was probably brought about by an increased effectiveness of the mucosal diffusion barrier."1 In rat perfused jejunal 936 on 11 May 2018 by guest. Protected by copyright.

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Twelve healthy volunteers were studied for two test periods, at the beginning of which they ingested a diarrheogenic load (60 g) of lactulose in 350 mL water with 10 g polyethylene glycol 4000 (PEG); the two periods were separated by a lactulose feeding period of 8 d, during which a nondiarrheogenic load (20 g) of lactulose was taken twice daily. The transit time and flow rates of water and lactulose in the distal ileum of four subjects were not different before and after the lactulose feeding period. In the other eight subjects, stool weight and frequency, fecal pH, and fecal outputs of carbohydrates and osmotic moieties after the ingestion of 60 g lactulose dropped significantly (P < 0.05) after the lactulose feeding period, whereas the orofecal transit time and fecal concentrations of beta-galactosidase and lactic acid increased (P < 0.05). We conclude that changes in colonic function induced by prolonged exposure to a nondiarrheogenic amount of lactulose mitigate the severity of the diarrhea because of the larger dose of lactulose.

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