Guar gum effects on plasma low-density lipoprotein and hepatic cholesterol metabolism in guinea pigs fed low- and high-cholesterol diets: a dose-response study.
Guinea pigs were fed semipurified diets containing either 0% or 12.5% guar gum (GG) with 0.04% cholesterol or increasing concentrations of GG (0%, 2.5%, 5%, 7.5%, 10%, and 12.5%) with 0.25% cholesterol (by wt). Compared to the 0% GG diet with 0.04% cholesterol, intake of the 12.5% GG diet with 0.04% cholesterol lowered plasma low-density-lipoprotein (LDL) concentrations, the ratio of LDL cholesteryl ester to protein, hepatic cholesterol concentrations, and the activity of acyl-CoA:cholesterol acyltransferase (ACAT), and increased 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity and hepatic apo B/E receptor number (P < 0.01). Intake of GG by animals fed 0.25% cholesterol diets resulted in modest effects on hepatic cholesterol pools and plasma LDL concentrations; however, significant negative correlations were found between both plasma LDL cholesterol and hepatic free cholesterol concentrations with the amount of dietary GG (P < 0.05). Hepatic HMG-CoA reductase was suppressed by the 0.25% cholesterol intake, and GG did not reverse this suppression. In contrast, ACAT activity was negatively correlated with the amount of dietary GG (P < 0.05), and GG intake increased the number of hepatic apo B/E receptors at all intakes with the 0.25% cholesterol diets. These results demonstrate that intake of GG significantly alters endogenous cholesterol metabolism by decreasing hepatic cholesterol pools, altering hepatic cholesterol homeostasis, and reducing plasma LDL concentrations.
Fernandez
M L
ML
Department of Nutritional Sciences, University of Arizona, Tucson 85721.
Sun
D M
DM
Tosca
M
M
McNamara
D J
DJ
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000008:administration & dosage / Q000378:metabolism; D005685:Galactans / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000097:blood* / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008351:Mannans / Q000008:administration & dosage / Q000494:pharmacology*; D053149:Plant Gums; D011897:Random Allocation; D002785:Sterol O-Acyltransferase / Q000378:metabolism
D002791:Cholesterol, Dietary; D005685:Galactans; D008077:Lipoproteins, LDL; D008351:Mannans; D053149:Plant Gums; D002784:Cholesterol; C007894:guar gum; D006903:Hydroxymethylglutaryl CoA Reductases; D002785:Sterol O-Acyltransferase