Mechanisms for the serum lipid-lowering effect of n-3 fatty acids

Both epidemiological and experimental studies have demonstrated that a high content of n-3 fatty acids in the diet lowers serum lipid concentration. However, the mechanism for this effect is unclear. In this present study it has been shown that labelled linolenic acid (18:3, n-3) is oxidized to a larger extent than linoleic acid (18:2,n-6) in isolated rat hepatocytes. Conversely, the incorporation of linolenic acid and the desaturated/chain-elongated products in VLDL-triacylglycerol is decreased compared with linoleic acid. Dietary n-3 fatty acids have probably a depressing effect on both hepatic triacylglycerol synthesis and on secretion of VLDL. The finding that n-3 fatty acids are transported from the liver as ketone bodies to a larger extent than n-6 fatty acids may thus explain that a high intake of n-3 fatty acids is not accompanied with hepatic steatosis.