The effect of palmitic acid on lipoprotein cholesterol levels

The present study assessed the effect of high versus low palmitic acid inta kes of plasma lipoprotein cholesterol levels and on rates for endogenous sy nthesis of cholesterol in normal and hypercholesterolemic subjects. 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 deuteriu m. A priming dose of deuterium was consumed and a second blood sample obtai ned 24 hours after the first sample. Isotope ratio mass spectrometry was us ed to determine the incorporation of deuterium into the newly synthesized c holesterol molecule and fractional synthetic rates were calculated. Four di ets were formulated to provide combinations of two levels of 16 : 0 at two levels of 18 : 2n-6. Subjects received each of the four diet treatments for 21 days, followed by washout periods of 21 days. Serum total cholesterol a nd LDL-cholesterol was not significantly affected by the high level of 16 : 0 when diets also contained a high level of 18 : 2n-6. Fractional synthesi s rates of cholesterol observed for each diet treatment did not differ sign ificantly, suggesting no relationship between the endogenous synthesis of c holesterol and dietary 16 : 0 content. The results indicate that 16 : 0 has no effect on serum lipoprotein profiles in the presence of recommended int akes for 18 : 2n-6.