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Dietary rhubarb (Rheum rhaponticum) stalk fibre stimulates cholesterol 7α-hydroxylase gene expression and bile acid excretion in cholesterol-fed C57BL/6J mice

Published online by Cambridge University Press:  09 March 2007

Vinti Goel ,
Sukhinder K. Cheema ,
Luis B. Agellon ,
Buncha Ooraikul  and
Tapan K. Basu
Vinti Goel
Affiliation:
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, CanadaT6G 2P5
Sukhinder K. Cheema
Affiliation:
Lipid and Lipoprotein Research Group and Department of Biochemistry, University of Alberta, Edmonton, Alberta, CanadaT6G 2S2
Luis B. Agellon
Affiliation:
Lipid and Lipoprotein Research Group and Department of Biochemistry, University of Alberta, Edmonton, Alberta, CanadaT6G 2S2
Buncha Ooraikul
Affiliation:
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, CanadaT6G 2P5
Tapan K. Basu*
Affiliation:
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, CanadaT6G 2P5
*
*Corresponding author: fax +1 403 492 9130, email tbasu@afns.ualberta.ca
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Abstract

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Both experimental and clinical studies have indicated that a novel source of dietary fibre, produced from rhubarb (Rheum rhaponticum) stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb fibre caused significant lowering of plasma cholesterol (-13 %) and the hepatic concentrations of total cholesterol (-34 %) and cholesteryl esters (-34 %). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7α-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7α-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb fibre.

Keywords

Rhubarb (Rheum rhaponticum)Bile acidsCholesterol 7α-hydroxylase
Type
Short communication
Information
British Journal of Nutrition , Volume 81 , Issue 1 , January 1999 , pp. 65 - 71
Copyright
Copyright © The Nutrition Society 1999

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