INDIVIDUAL FATTY-ACID EFFECTS ON PLASMA-LIPIDS AND LIPOPROTEINS - HUMAN STUDIES

The purpose of this review is to summarize our current understanding o f the cholesterolemic effects of individual fatty acids. Although hist orically there has been great interest in the fatty acid classes, it h as been only recently that emphasis has shifted to individual fatty ac ids. Consequently, and in conjunction with the methodologic challenges inherent in studying individual fatty acids, our database is relative ly modest. Nonetheless, it is clear that saturated fatty acids are hyp ercholesterolemic and that unsaturated fatty acids elicit a hypocholes terolemic effect compared with saturated fatty acids. The question at hand is, What are the relative cholesterolemic effects of the major sa turated and unsaturated fatty acids in the diet? On the basis of a lim ited number of well-controlled studies, it appears that myristic acid is the most potent saturated fatty acid. Of the saturated fatty acids, stearic acid is uniquely different in that it appears to be a neutral fatty acid. Monounsaturated fatty acids appear to exert a neutral eff ect or to be mildly hypocholesterolemic. trans Fatty acids elicit effe cts that are intermediate to those of the hypercholesterolemic saturat ed fatty acids and the cis-monounsaturated and cis-polyunsaturated fat ty acids. Polyunsaturated fatty acids elicit the most potent hypochole sterolemic effects. Studies are needed to establish the potency with w hich each fatty acid affects plasma total and lipoprotein cholesterol concentrations as well as the mechanisms that account for their marked ly different effects. This information will be useful in making dietar y recommendations for individual fatty acids that may further reduce r isk of chronic diseases in the United States.