A method of detecting, diagnosing and prognosticating atherosclerosis by measuring the activities of Δ6 and Δ5 desaturases is described. It is suggested that enhancing the activities of Δ6 and Δ5 desaturases results in an increase in the plasma, leukocyte, platelet and endothelial cell levels of γ-linolenic, dihomo-γ-linolenic, arachidonic, stearidonic, 20:4 ω-3, eicosapentaneoic and docosahexaenoic acids and PGE1 (prostaglandin E1), prostacyclin (PGI2), prostaglandin I3 (PGI3), lipoxins, resolvins, protectins, nitric oxide, and nitrolipids that prevent, arrest and reverse atherosclerosis. The invention is also directed to the delivery of proteins, peptides, lipids, lipoproteins, glycolipids, statins and troglitazones and their derivatives, and other compounds (synthetic or natural), cDNA clones and genes of Δ6 and Δ5 desaturases to enhance the activities of Δ6 and Δ5 desaturases in vivo to prevent, arrest, reverse and treat atherosclerosis.