Magnitude of dietary effects on plasma cholesterol concentration: role of sex and apolipoprotein E phenotype

The effects of fat-controlled, low-cholesterol and high-fat, high-cholesterol diets pursued for 4 weeks on plasma lipids and lipoproteins were studied in 44 healthy middle-aged subjects (22 women and 22 men). All the calories were supplied from the hospital kitchen. When the subjects were switched from the fat-controlled, low-cholesterol diet to the high-fat, high-cholesterol diet the average increase in total cholesterol was 1.2 mmol/l (28%), ranging from 0.2 to 2.7 mmol/l (4-56%). At the same time the average increase in LDL cholesterol was 1.0 mmol/l (39%), ranging from 0.1 to 2.4 mmol/l (3-90%). Interestingly, the men responded to the dietary changes more sensitively than the women. The increase in total cholesterol from the low-fat to the high-fat diet was 31% for the men and 25% for the women (P < 0.05), the corresponding increases in LDL cholesterol being 42% and 37%, respectively (P < 0.05). A marked increase in HDL cholesterol was observed when the subjects were switched from the low-fat to the high-fat diet, the increase being 30% for the men and 20% for the women. The absolute and percentage lipid changes on the two diets were equal in the subjects with the common apolipoprotein E phenotype 3 3 and in those homozygous and heterozygous for the epsilon 4 allele ( E4 4 and E4 3). Overall, the data show that middle-aged men, the main risk group for coronary heart disease, seem to be particularly responsive to this diet modification, and the effects of a prudent diet can also be obtained in subjects with a genetic predisposition to a moderate elevation in plasma cholesterol level, i.e., those who fall into the phenotypic categories E4 4 and E4 3.