DIETARY MANIPULATION OF ARACHIDONIC ACID METABOLISM
Because arachidonic acid is derived from dietary linoleic and α-linolenic acids, which are essential fatty acids, the effects ofdietary manipulation on arachidonic acid metabolism have been extensively studied. Two approaches have been used. The first adds corn, safflower, and sunflower oils, which contain linoleic acid (C18:2), to the diet. The second approach adds oils containing eicosapentaenoic (C20:5) and docosahexaenoic acids (C22:6), so-called omega-3 fatty acids, from cold-water fish. Both types of diet change the phospholipid composition of cell membranes by replacing arachidonic acid with the dietary fatty acids. Diets high in fish oils have been shown to impact ex vivo indices of platelet and leukocyte function, blood pressure, and triglycerides with dif-ferent dose-response relationships. There is an abundance of epi-demiologic data relating diets high in fatty fish to a reduction in the incidence of myocardial infarction and sudden cardiac death although there is more ambiguity about stroke. Of course, epide-miologic data may confound such diets with a reduction in satu-rated fats and other elements of a “healthy” lifestyle. In addition, some data from prospective randomized trials suggest that such dietary interventions may reduce the incidence of sudden death. Experiments in vitro suggest that fish oils protect against experi-mentally induced arrhythmogenesis, platelet aggregation, vaso-motor spasm, and dyslipidemias.