Background: The magnitude of the influence of the apolipoprotein (apo) E genotype on the lipid response to different cholesterol-lowering diet modifications has been controversial.
Objective: The aim of the study was to investigate the effect of apo E genotype on serum lipid response to the separate modification of dietary fat and cholesterol.
Design: A prospective study design with the 3 main apo E genotype groups (3/3, 3/4, and 4/4; n = 15 in each group) was used. Groups were matched for sex, age, body mass index, menopausal status, and baseline serum cholesterol concentration. Subjects followed 3 different diets in fixed order: 1) a standardized baseline diet (38% fat, 300 mg cholesterol/d), 2) a modified National Cholesterol Education Program (NCEP) diet (34% fat, 265 mg cholesterol/d), and 3) the modified NCEP diet + cholesterol (566 mg cholesterol/d). Subjects were middle-aged (50.9 +/- 8.0 y) and mildly hypercholesterolemic (6.55 +/- 1.05 mmol/L).
Results: The genotype groups differed in their total cholesterol response to the NCEP diet; the mean (95% CI) decrease being greatest, -14.1% (-19.8%, -8.6% ), in subjects with apo E genotype 4/4 (P = 0.03, analysis of variance). The increase in total cholesterol after addition of 300 mg cholesterol was also greatest in subjects with apo E 4/4 [10.4% (5.8%, 15.1%)] (P = 0.03, analysis of variance).
Conclusions: Apo E genotype modified the lipid response to changes in both dietary fat and cholesterol in mildly hypercholesterolemic subjects; the response was greatest in subjects with apo E genotype 4/4 and even a moderate increase in dietary cholesterol resulted in a 10% elevation in serum total cholesterol in them.