| Cholesterol-lowering effects of guar gum: changes in bile acid pools and intestinal reabsorption. | |
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MedLine Citation:
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PMID: 10858029 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Soluble fibers such as guar gum (GG) may exert cholesterol-lowering effects. It is generally accepted that bile acid (BA) reabsorption in portal blood is reduced, thus limiting the capacity of BA to down-regulate liver cholesterol 7alpha-hydroxylase, the rate-limiting enzyme of BA synthesis. In the present work, rats were adapted to fiber-free (FF) or 5% GG diets (supplemented or not with 0.25% cholesterol), to investigate various aspects of enterohepatic BA cycling. GG in the diet at a level of 5% elicited a significant lowering of plasma cholesterol during the absorptive period, in cholesterol-free (-13%) or 0.25% cholesterol (-20%) diet conditions. In rats adapted to the GG diets, the small intestinal and cecal BA pools and the ileal vein-artery difference for BA were markedly enhanced; reabsorption in the cecal vein was also enhanced in these rats. [14C]Taurocholate absorption, determined in perfused ileal segments, was not significantly different in rats adapted to the FF or GG diet, suggesting that a greater flux of BA in the ileum might support a greater ileal BA reabsorption in rats adapted to the GG diet. In contrast, capacities for [14C]cholate absorption from the cecum at pH 6.5 were higher in rats adapted to the GG diet than to the FF diet. Acidification of the bulk medium in isolated cecum (from pH 7.1 down to pH 6.5 or 5.8) or addition of 100 mM volatile fatty acids was also found to stimulate cecal [14C]cholate absorption. These factors could contribute to accelerated cecal BA absorption in rats fed the GG diet. The effects of GG on steroid fecal excretion thus appear to accompany a greater intestinal BA absorption and portal flux to the liver. These results suggest that some mechanisms invoked to explain cholesterol-lowering effect of fibers should be reconsidered. |
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Authors:
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S Moriceau; C Besson; M A Levrat; C Moundras; C Rémésy; C Morand; C Demigné |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Lipids Volume: 35 ISSN: 0024-4201 ISO Abbreviation: Lipids Publication Date: 2000 Apr |
Date Detail:
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Created Date: 2000-10-02 Completed Date: 2000-10-02 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0060450 Medline TA: Lipids Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 437-44 Citation Subset: IM |
Affiliation:
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Unité Maladies Métaboliques & Micronutriments, INRA de Theix, St-Genès-Champanelle, France. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Arteries Bile Acids and Salts / blood, metabolism* Carbon Radioisotopes Cecum / blood supply, metabolism Cholesterol / blood* Cholesterol, Dietary / pharmacology Dietary Fiber / pharmacology* Galactans / pharmacology* Hydrogen-Ion Concentration Ileum / blood supply Intestinal Absorption* Intestine, Small / metabolism Kinetics Male Mannans / pharmacology* Plant Gums Rats Rats, Wistar Taurocholic Acid / metabolism Veins |
| Chemical | |
Reg. No./Substance:
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0/Bile Acids and Salts; 0/Carbon Radioisotopes; 0/Cholesterol, Dietary; 0/Galactans; 0/Mannans; 0/Plant Gums; 57-88-5/Cholesterol; 81-24-3/Taurocholic Acid; 9000-30-0/guar gum |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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