Polymorphism exon 1 variant at the locus of the scavenger receptor class B type I gene: influence on plasma LDL cholesterol in healthy subjects during the consumption of diets with different fat contents

Abstract

Background: The association between polymorphisms in the scavenger receptor class B type I (SRB-I) gene and variations in basal plasma concentrations of cholesterol in humans has recently been described. Objective: The objective of the study was to determine whether the exon 1 variant (G→A) at the SRB-I gene is associated with the lipid response to the content and quality of dietary fat in healthy subjects. Design: We studied 97 healthy volunteers with exon 1 polymorphism [65 homozygous for allele 1 (1/1) and 32 heterozygous for allele 2 (1/2)]. Both groups consumed 3 diets lasting 4 wk each. The first was a saturated fatty acid (SFA)–rich diet (38% fat, 20% SFA), which was followed by a carbohydrate (Cho)–rich diet (30% fat, < 10% SFA, 55% carbohydrate) or a monounsaturated fatty acid (MUFA), olive oil–rich diet (38% fat, 22% MUFA) according to a randomized crossover design. At the end of each dietary period, plasma concentrations of triacylglycerol and of total, LDL, and HDL cholesterol were measured. Results: Carriers of the 1/2 genotype had a trend toward higher concentrations of LDL cholesterol (P < 0.11) after the SFA–rich diet than did those who were homozygous for 1/1. Carriers of the mutation showed a significantly greater (P = 0.007) decrease in LDL-cholesterol concentrations (−23%) in changing from an SFA–rich diet to a Cho–rich diet than did noncarriers of the mutation (−16%). Conclusion: Carriers of the minority allele, 1/2, are more susceptible to the presence of SFA in the diet because of a greater increase in LDL cholesterol.