Effect of pectin on jejunal glucose absorption and unstirred layer thickness in normal man.

Abstract

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.

Physiological measurements of luminal stirring in the dog and human small bowel.

“…However, maximal estimates of unstirred layer thickness in man can be easily obtained from previous reports of glucose absorption from infusates containing low concentrations of glucose (9,10,22,(27)(28)(29)(30)(31). For this calculation, REP was assumed to' be negligible and the area of the luminal aqueous barrier was assumed to have an area equal to a cylinder over the villous tips.…”

“…In vivo measurements in rats generally have yielded unstirred layers of at least 300 gm thickness (3,11,(14)(15)(16)(17), and in man and dogs this layer is said to be greater than 600,gm (9,10,12,13).…”

“…A wide variety of in vitro (1)(2)(3)(4)(5)(6)(7)(8) and in vivo (3,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) studies have suggested that luminal stirring is relatively poor and large aqueous diffusion barriers build up adjacent to the mucosa. Expressed as a uniform thickness of unstirred water, this preepithelial diffusion barrier in man is thought to produce a resistance equivalent to an unstirred layer of greater than 600 Mm (9,10,12). Such a relatively enormous diffusion barrier would drastically reduce the absorption of any compound that is rapidly transported across the mucosa.…”

Effect of psyllium on gastric emptying, hunger feeling and food intake in normal volunteers: a double blind study

“…It has been shown that the increased viscosity of the food obtained with soluble ®bres may further reduce the rate of small intestinal absorption. Indeed an increase in the viscosity of food may have several effects: (a) to slow down the small intestinal transit (Low, 1988;Cherbut et al, 1994); but Cummings et al (1979) did not ®nd any modi®cation of oro-cecal transit time with pectin; (b) to reduce the interaction between food nutrients and digestive enzymes (Flourie  et al, 1984;Cummings et al, 1979; to increase the time for nutrient diffusion, by increasing the thickness of the unstirred water layer (Flourie  et al, 1984;Rydning & Berstad, 1986). This is consistent with the studies which have demonstrated that soluble ®bres could decrease the area under the curve of serum glucose after a duodenal glucose load (Berggren et al, 1993).…”

Effects of Salmon Nasal Cartilage Proteoglycan on Plasma Glucose Concentration and Active Glucose Transport in the Small Intestine

“…Cellulose and pectin are known to be poorly absorbable polysaccharides. It has been reported that they suppress increases in plasma glucose concentration and glucose absorption in the small intestine (8,9). We hypothesized that salmon PG may have effects similar to those of cellulose and pectin.…”