Changes in plasma lipids and lipoproteins after a modified fat diet

20 male and female patients with type II hyperlipoproteinaemia and 10 normal male and female subjects were fed for 11--15 days a eucaloric diet containing less than 300 mg cholesterol with a polyunsaturated to saturated fatty-acid ratio of about 2.0. Male subjects and patients and female patients showed statistically significant decreases in plasma total cholesterol and low-density lipoprotein (LDL) cholesterol levels; the change in LDL-cholesterol was not significant in female subjects. The changes in lipid and lipoprotein levels in patients were greater than those in subjects, (except for the changes in high-density lipoprotein (HDL) in women, which were similar), which suggested that the magnitude of change depended on initial levels. This difference was not present when the data were evaluated as percent change. Mean levels of HDL-cholesterol decreased in both patients and subjects. However, the proportion of total cholesterol contributed by HDL and LDL, and hence the HDL/LDL ratio, was unchanged from pre-diet levels.