The role of unnatural dietary trans and cis unsaturated fatty acids in the epidemiology of coronary artery disease.

During 1956 the first report on the hypocholesterolemic effect of unsaturated fatty acids of plant and marine origin was published in The Lancet. Consequently it was stated in a Lancet Editorial that hydrogenation of vegetable oils could have contributed to the causation of coronary artery disease and predicted that a decade would probably be required to resolve this question. However, after the lapse of three decades this issue would appear to be no nearer to a clear answer now than it was then. During 1956 hydrogenation was assumed to effect only a reduction in the level of unsaturated fatty acids in the products produced from hydrogenated oils. However, since that time essential fatty acid metabolic pathways to eicosanoids were discovered and described. Also large quantities of unnatural trans and cis unsaturated fatty acids have been shown to form during hydrogenation and these occur in margarines and many other common foods in high concentrations. It has also been shown that these unnatural trans and cis fatty acids block essential fatty acid metabolism by the competitive inhibition of the desaturase enzyme delta-6-desaturase. Therefore some of the possible metabolic mechanisms whereby "hydrogenation plants could have contributed to the causation of a major disease" have become clearer during the last three decades. Despite a recent conclusion by an ad hoc FDA panel that there need be little concern about the effects of trans fatty acids in the American diet on health, it is nevertheless proposed that on the basis of available evidence, unnatural dietary trans and cis unsaturated fatty acid isomers should be regarded as a definite risk factor in the etiology of coronary artery disease.