The cholesterol-lowering effect of guar gum in rats is not accompanied by an interruption of bile acid cycling.
A viscous hydrocolloid (guar gum, GG; 2.5% of the diet) or a steroid sequestrant (cholestyramine; 0.5% of the diet) was included in semipurified diets containing 0.2% cholesterol to compare the cholesterol-lowering effects of each agent in rats. In the present model, GG significantly lowered plasma cholesterol (-25%), especially in the density < 1.040 kg/L fraction, whereas cholestyramine was less potent. Bile acid fecal excretion significantly increased only in rats fed cholestyramine, similar to the cecal bile acid pool; the biliary bile acid secretion was accelerated by GG, but not their fecal excretion, whereas GG effectively enhanced neutral sterol excretion. As a result, the total steroid balance (+13 micromol/d in the control) was shifted toward negative values in rats fed the GG or cholestyramine diets (-27 or -50 micromol/d, respectively). Both agents induced liver 3-hydroxy-3-methylglutaryl-CoA reductase, but cholestyramine was more potent than GG in this respect. The present data suggest that, at a relative low dose in the diet, GG may be more effective than cholestyramine in lowering plasma cholesterol by impairing cholesterol absorption and by accelerating the small intestine/liver cycling of bile acids, which is interestingly, accompanied by reduction of bile acid concentration in the large intestine.
Favier
M L
ML
Laboratoire des Maladies Métaboliques et Micronutrients, I.N.R.A. de Clermont-Ferrand/Theix, France.
Bost
P E
PE
Demigné
C
C
Rémésy
C
C
D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D001659:Biliary Tract / Q000378:metabolism; D001837:Body Weights and Measures; D002432:Cecum / Q000378:metabolism; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D002792:Cholestyramine Resin / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005285:Fermentation; D005685:Galactans / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D008055:Lipids / Q000097:blood; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008351:Mannans / Q000378:metabolism*; D053149:Plant Gums; D051381:Rats; D017208:Rats, Wistar; D013261:Sterols / Q000032:analysis
D001647:Bile Acids and Salts; D004043:Dietary Fiber; D005685:Galactans; D008055:Lipids; D008351:Mannans; D053149:Plant Gums; D013261:Sterols; D002792:Cholestyramine Resin; D002784:Cholesterol; C007894:guar gum; D006903:Hydroxymethylglutaryl CoA Reductases