Guar gum does not impair the absorption and utilization of dietary nitrogen but affects early endogenous urea kinetics in humans.
BACKGROUND
Viscous gums enhance viscosity in the upper gastrointestinal lumen, quickly disturbing motility and promoting fluid secretion.


OBJECTIVE
We sought to determine whether guar gum could acutely affect the absorption and utilization of dietary nitrogen and whether these luminal effects could also perturb the kinetics of urea.


METHODS
We studied the short-term effect of adding 1% of highly viscous guar gum to a (15)N-labeled protein meal (30 g soy protein isolate in 500 mL water) during the postprandial phase in humans. The effects on bioavailability were studied by using the [(13)C]glycine breath test (to assess gastric emptying) and (15)N enrichment in plasma amino acids (for systemic amino acid bioavailability). The kinetics of dietary and endogenous urea were assessed in plasma and urine.


RESULTS
Guar gum modulated the gastric emptying kinetics of the liquid phase of the meal slightly (P < 0.05), but had no significant effect on either the systemic appearance of dietary amino acids or plasma and urinary dietary urea kinetics. Without significantly affecting plasma urea concentrations, guar gum reduced by approximately 40% the urinary excretion of endogenous urea for the first 2-h period after the meal (P < 0.01), although endogenous urinary excretion was similar at later stages.


CONCLUSIONS
Guar gum did not significantly affect the bioavailability or utilization of dietary protein. We showed an early effect of guar gum on endogenous urea kinetics, which most probably arose from very early, short-term stimulation of the intestinal disposal of endogenous urea, at the expense of its urinary excretion.
Mariotti
F
F
UMR INRA-INAPG de Physiologie de la Nutrition et du Comportement Alimentaire, Paris, France. francois.mariotti@inapg.inra.fr
Pueyo
M E
ME
Tomé
D
D
Benamouzig
R
R
Mahé
S
S
D000328:Adult; D000596:Amino Acids / Q000097:blood*; D001682:Biological Availability; D001944:Breath Tests; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D005685:Galactans / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D008351:Mannans / Q000008:administration & dosage / Q000494:pharmacology*; D009584:Nitrogen / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D053149:Plant Gums; D019518:Postprandial Period; D014508:Urea / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics
D000596:Amino Acids; D004044:Dietary Proteins; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D014508:Urea; C007894:guar gum; D009584:Nitrogen