Fish oils in cardiovascular disease

Although several studies have reported an inverse relationship between the dietary history of fish intake and the prospective incidence of death from coronary heart disease, it is unclear whether these results represent the effects of n-3 fatty acids themselves or whether they merely reflect a more fundamental alteration in diet, such as a reduction in saturated fatty acids. n-3 fatty acids alter platelet eicosanoid formation, replacing arachidonate derived thromboxane (Tx)A2 with the biologically inert TxA3. However, they are a relatively inefficient approach to platelet inhibition. This is evident from results obtained in a model of coronary thrombosis followed by thrombolysis with tissue plasminogen activator (tPA). By contrast, high doses of n-3 fatty acids (15 g day-1) significantly reduced blood pressure in mild hypertensives in a double-blind, controlled study characterized by a prolonged run-in period and adequate follow-up. Fish oils inhibit the vascular proliferative response to injury in a variety of animal models, apparently independently of their effects on lipoprotein metabolism. Recent results imply that they may selectively interfere with the vascular expression of mitogenic peptides.