Fish oils and their possible role in the treatment of cardiovascular diseases

Abstract

The multifactorial origin of arteriosclerotic cardiovascular diseases is well recognized. It recently has been shown that n-3 fatty acids (FA), contained in fish oils, may correct some of the most important cardiovascular risk factors and may interfere with key steps in the formation of the atherosclerotic plaque. These findings have raised such interest that many reports have been published with somewhat conflicting results. In hypertensive patients, randomized controlled studies have confirmed that n-3 FA may reduce systolic blood pressure by 5 mmHg and diastolic by 4 mmHg. The decrease in pressure, which could be larger if dietary sodium restriction is added, is probably due to the shift of balance between vasoconstrictive and vasodilator eicosanoids toward vasodilatation. n-3 FA correct endogenous hypertriglyceridemia, but the effects on low-density lipoprotein and high-density lipoprotein cholesterol are less clear cut, since an increase in low-density lipoprotein and a decrease in high-density lipoprotein may be observed in selected patients. As far as the glucose metabolism in patients with diabetes mellitus is concerned, inhibition of the beta cell by n-3 FA has been reported. n-3 FA reduce platelet aggregation, blood viscosity, plasma levels of fibrinogen, PF4 and beta-thromboglobulin and increase capillary flow and red cell membrane fluidity, but their long-term effects on cardiovascular mortality are largely unknown. Medium-term studies, however, have shown a decreased risk of myocardial reinfarction and of restenosis after percutaneous transluminal coronary angioplasty with n-3 FA supplementation. Pure, highly concentrated triglycerides and ethyl esters of n-3 FA are available and will allow further investigations on the dose-response ratio in humans.