title: Beta-glucan extracts inhibit the in vitro intestinal uptake of long-chain fatty acids and cholesterol and down-regulate genes involved in lipogenesis and lipid transport in rats.
abstract: BACKGROUND
  Dietary fiber reduces the intestinal absorption of nutrients and the blood concentrations of cholesterol and triglycerides.
  
  
  OBJECTIVE
  We wished to test the hypothesis that high-viscosity (HV) and low-viscosity preparations of barley and oat beta-glucan modify the expression of selected genes of lipid-binding proteins in the intestinal mucosa and reduce the intestinal in vitro uptake of lipids.
  
  
  METHODS
  Five different beta-glucan extracts were separately added to test solutions at concentrations of 0.1-0.5% (wt/wt), and the in vitro intestinal uptake of lipids into the intestine of rats was assessed. An intestinal cell line was used to determine the effect of beta-glucan extracts on the expression of intestinal genes involved in lipid metabolism and fatty acid transport.
  
  
  RESULTS
  All extracts reduced the uptake of 18:2 when the effective resistance of the unstirred water layer was high. When the unstirred layer resistance was low, the HV oat beta-glucan extract reduced jejunal 18:2 uptake, while most extracts reduced ileal 18:2 uptake. Ileal 18:0 uptake was reduced by the HV barley extract, while both jejunal and ileal cholesterol uptakes were reduced by the medium-purity HV barley extract. The inhibitory effect of HV barley beta-glucan on 18:0 and 18:2 uptake was more pronounced at higher fatty acid concentrations. The expression of genes involved in fatty acid synthesis and cholesterol metabolism was down-regulated with the HV beta-glucan extracts. beta-Glucan extracts also reduced intestinal fatty-acid-binding protein and fatty acid transport protein 4 mRNA.
  
  
  CONCLUSIONS
  The reduced intestinal fatty acid uptake observed with beta-glucan is associated with inhibition of genes regulating intestinal uptake and synthesis of lipids. The inhibitory effect of beta-glucan on intestinal lipid uptake raises the possibility of their selective use to reduce their intestinal absorption.
authors.affiliation: Nutrition and Metabolism Group, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Drozdowski
authors.forename: Raylene A
authors.initials: RA
authors.lastname: Reimer
authors.forename: Feral
authors.initials: F
authors.lastname: Temelli
authors.forename: Rhonda C
authors.initials: RC
authors.lastname: Bell
authors.forename: Thava
authors.initials: T
authors.lastname: Vasanthan
authors.forename: Alan B R
authors.initials: AB
authors.lastname: Thomson
mesh_terms: D000818:Animals; D001483:Base Sequence; D002784:Cholesterol / Q000378:metabolism*; D017931:DNA Primers; D015536:Down-Regulation / Q000187:drug effects*; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D007583:Jejunum / Q000187:drug effects* / Q000378:metabolism; D050356:Lipid Metabolism; D050155:Lipogenesis / Q000187:drug effects*; D008297:Male; D051381:Rats; D047071:beta-Glucans / Q000494:pharmacology*
chemical_list: D017931:DNA Primers; D005227:Fatty Acids; D047071:beta-Glucans; D002784:Cholesterol