Dietary fish oil or purified preparations of omega-3 fatty acids appear promising as effective antithrombotic or antiatherosclerotic agents for the future. The potential antithrombotic action of fish oil appears to center around its effects on platelets and blood vessel walls. When humans ingest moderate doses of fish oils, the bleeding time is mildly but regularly prolonged, platelet aggregation is inhibited, and platelet capacity to produce thromboxane is reduced. Fish oil also appears to reduce heightened platelet-vascular interactions found in patients with severe atherosclerotic vascular disease and to reduce vasoconstriction and platelet deposition on injured vascular surfaces in experimental animal models.
Fish oil has also been effective in the inhibition of diet-induced atherosclerosis of coronary arteries, aorta, and other vessels in experimental animals including swine and two species of monkeys. The mechanism of its antiatherogenic effect is not known but seems to be unrelated to the lowering of plasma cholesterol and may involve actions on monocytes, vessel walls, or perhaps platelets. further
However, it should be emphasized that there are no prospective controlled clinical trials in humans in which fish oil was adequately tested as an antithrombotic or antiatherosclerotic agent. Until the results of such trials are available, the use of fish oil or purified omega-3 fatty acids cannot be recommended for prophylaxis of or therapy for vascular disease or thrombosis in humans. Furthermore, additional information must be gathered in long-term animal and human studies to prove that the daily ingestion of fish oil is safe as well as effective. More evidence must be generated on the potential for bleeding, the possible increase in hemorrhagic or thrombotic stroke, and potential carcinogenic or immunosuppressive properties of fish oil.