APOE GENOTYPE DOES NOT PREDICT LIPID RESPONSE TO CHANGES IN DIETARY SATURATED FATTY-ACIDS IN A HETEROGENEOUS NORMOLIPIDEMIC POPULATION

Recent studies have suggested that variations in apoE genotypes may in fluence the magnitude of plasma lipid changes in response to dietary i nterventions. We examined the ability of apoE genotype to predict plas ma lipid response to reductions in percent of calories from total fat (TF) and saturated fat (SF) in a normolipidemic study population (n=10 3) heterogeneous with respect to age, gender, race, and menopausal sta tus. Three diets, an average American diet (34.3% TF, 15.0% SF), an AH A Step 1 diet (28.6% TF, 9.0% SF), and a low saturated fat (Low-Sat) d iet (25.3% TF, 6.1% SF) were each fed for a period of 8 weeks in a thr ee-way crossover design. Cholesterol was kept constant at 275 mg/d; mo nounsaturated and polyunsaturated fat were kept constant at approximat ely 13% and 6.5% of calories, respectively. Fasting lipid levels were measured during each of the final 4 weeks of each diet period. Partici pants were grouped by apoE genotype: E2 (E2/2, E2/3, E2/4); E3 (E3/3); E4 (E3/4, E4/4). Relative to the average American diet, both the Step 1 and Low-Sat diets significantly reduced total cholesterol, LDL chol esterol, and HDL cholesterol in all three apoE genotype groups. No evi dence of a significant diet by genotype interaction, however, could be identified for any of the measured lipid and lipoprotein end points. Additional analysis of the data within individual population subgroups (men and women, blacks and whites) likewise provided no evidence of a significant diet by genotype interaction. Thus, in a heterogeneous, n ormolipidemic study population, apoE genotype does not predict the mag nitude of lipid response to reductions in dietary saturated fat.