Cholesterol-rich diet induced changes in plasma lipids in relation to apolipoprotein E phenotype in healthy students

The hypothesis that apolipoprotein E (apoE) polymorphism modulates an individual's response to cholesterol-rich diet was tested in 36 healthy normolipidaemic students with apoE phenotypes E3/2 (n = 9), E3/3 (n = 11), E4/3 (n = 13) and E4/4 (n = 3). The subjects were instructed to eat their usual diets, omitting eggs, for three weeks (baseline). This was followed by a diet high in cholesterol (750 mg/day, from egg yolks) for three weeks (intervention) after which they returned to their normal diet (without eggs for three weeks). Concentrations of plasma lipids and apolipoprotein B, and the composition of total fatty acids were monitored. At baseline, there were no statistically significant differences in lipid concentrations between the phenotype groups. The cholesterol-rich diet induced significant increases in total cholesterol, LDL cholesterol, and apoB in all apoE groups (P less than 0.001). The magnitudes of these increases were similar in groups E3/2, E3/3, and E4/3, in which total cholesterol concentration rose by 13%, 18%, and 12%, respectively. Stronger responses were observed in the small group of E4/4 subjects, in whom the increases in total cholesterol, LDL cholesterol, and apoB were 2.3-fold (P = 0.054), 2.25-fold (P = 0.02) and 2.3-fold (P = 0.004), respectively, compared with all the other phenotypes studied.