Essential Fatty Acids in Serum Lipids of Young Male Rural Guatemalans and Urban North Americans

I1T HAS BEEN suggested that polyunsaturated fatty acids control, by some mechanism, the levels of blood cholesterol and other blood lipids.1 S Sinclair suggested4 that dietary deficiency of essential fatty acids is responsible for human atherosclerosis. He proposed t-hat the mechanism of atherogenesis involves a replacement of the polyunsaturated fatty acids in serum cholesterol esters by saturated and nonessential unsaturated fatty acids, followed by a deposition of the less soluble saturated esters in the arterial wall resulting in atheromatous lesions. It is not clear from the literature whether data on the composition of human serum lipids support or refute the hypothesis of Sinclair. Subjects with clinical disease due to atherosclerosis, in some studies, have a smaller proportion of polyunsaturated fatty acids, principally linoleic and arachidonic acids, in their serum lipids than "healthy" subjects from the same population.5-9 The triene/tetraene fatty acid ratio has also been found to be elevated in subjects with clinical manifestations of atherosclerosis,6 which suggests a relative deficiency of essential fatty acids.'0 Herdenstam"l and James et al.,'2 found, to the contrary, the same proportion of polyunsaturated fatty acids in serum lipids of "healthy" and "atherosclerotic" subjects. Hammond and Lundberg5 reported serum concentrations of polyunsaturated fatty acids in healthy Guatemalans equal to or exceeding