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 remov al of LDL cholesterol from the circulation by receptor-dependent trans port. 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 at oms suppress receptor-dependent LDL-cholesterol transport into the liv er, increase the LDL-cholesterol production rate, and raise the plasma LDL-cholesterol concentration. The 9-cis 18:1 fatty acid restores rec eptor activity, lowers the production rate, and decreases the plasma L DL-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.