DIETARY SATURATED AND TRANS-FATTY-ACIDS AND LIPOPROTEIN METABOLISM

Earlier studies have shown that not all saturated fatty acids are equally hypercholesterolaemic: stearic acid (C18:0) and saturated fatty acids with less than 12 carbon atoms are thought not to raise serum cholesterol levels. This suggests that the cholesterol-raising effects of saturated fatty acids can be attributed to lauric acid (C12:0), myristic acid (C14:0) and palmitic acid (C16:0). These three saturated fatty acids also have different effects on serum total cholesterol levels. Results from recent controlled dietary experiments suggest that lauric acid raises serum total and low- density lipoprotein (LDL) cholesterol levels slightly less, and myristic acid more, as compared with palmitic acid. Myristic acid, however, also causes higher levels of high-density lipoprotein (HDL) cholesterol. Stearic acid has only a slight effect on serum LDL and HDL cholesterol levels as compared with oleic acid. Trans monounsaturated fatty acids, however, increase LDL and decrease HDL cholesterol levels. Precise effects on lipoproteins of short and medium chain triglycerides (C4:0-C10:0) have never been examined.