The effect of palmitic acid on lipoprotein cholesterol levels and endogenous cholesterol synthesis in hyperlipidemic subjects.

The present study assesses the effect of high vs. low palmitic acid intakes on plasma lipoprotein cholesterol levels and on rates for endogenous synthesis of cholesterol in healthy and hyperlipidemic subjects. Four diets were formulated to provide combinations of 16:0 at two levels of 18:2n-6. Subjects received each diet treatment for 21 d, followed by washout periods of 21 d. On day 21 of each diet treatment, a fasting blood sample was drawn for lipoprotein determination and to provide a measure of the background level of deuterium. A priming dose of deuterium was consumed and a second blood sample obtained 24 h after the first sample. Isotope ratio mass spectrometry was used to determine the incorporation of deuterium into the newly synthesized cholesterol molecule, and fractional synthetic rates were calculated. Serum total cholesterol and low density lipoprotein-cholesterol was not significantly affected by the high level of 16:0 when diets also contained a high level of 18:2n-6. There was no effect of dietary 16:0 on high density liproprotein-cholesterol at either the high or low levels of intake. The results indicate that 16:0 has no effect on serum lipoprotein profiles in the presence of recommended intakes for 18:2n-6.