Effect of long-chain fatty acids on low-density-lipoprotein-cholesterol metabolism.

The concentration of cholesterol in the low-density-lipoprotein (LDL) fraction of plasma is one of the major risk factors for coronary heart disease. Steady-state concentrations of LDL cholesterol in the plasma are determined primarily by the production rate and the rate of removal of LDL cholesterol from the circulation by receptor-dependent transport. The magnitude of these two processes is affected by the type of fatty acid in the diet. Saturated fatty acids with 14 and 16 carbon atoms suppress receptor-dependent LDL-cholesterol transport into the liver, increase the LDL-cholesterol production rate, and raise the plasma LDL-cholesterol concentration. The 9-cis 18:1 fatty acid restores receptor activity, lowers the production rate, and decreases the plasma LDL-cholesterol concentration. In contrast with these fatty acids, the 18:0 and 9-trans 18:1 fatty acids are biologically inactive and so do not change the circulating LDL-cholesterol concentration.