LDL particle size and LDL and HDL cholesterol changes with dietary fat and cholesterol in healthy subjects

We have conducted a dietary trial in 54 men and 51 women with a wide range of fasting cholesterol values to examine the use of low density lipoprotein (LDL) particle size to predict the lipoprotein response to dietary fat and cholesterol. After a 2-week low fat period, subjects were given two liquid supplements in addition to their low fat diet for 3 weeks each, one containing 31-40 g of fat and 650-845 mg of cholesterol, the other fat free. LDL particle type was determined by 3-15% gradient gel electrophoresis. On multiple regression, LDL type was independently related to plasma triglyceride (P < 0.001), waist circumference (P < 0.01), and high density lipoprotein (HDL) (P < 0.001) accounting for 56% of the variance in LDL type in the whole group. Change in LDL cholesterol with dietary fat and cholesterol was unrelated to LDL particle size in either men or women. However, change in HDL cholesterol in men was strongly related to LDL particle type (r = -0.52, P = 0.001) and change in HDL2 cholesterol in women was related to LDL particle type (r = -0.40, P < 0.01). In conclusion, we are unable to confirm the finding that LDL particle type can predict changes in LDL cholesterol following changes in dietary fat intake. However, LDL particle type can independently predict changes in HDL cholesterol in men and accounts for 27% of the variance.