Fish oil: effectiveness as a dietary supplement in the prevention of heart disease.

The low incidence of reported heart attacks and cardiovascular-related deaths in Greenland Eskimos and the Japanese has generated interest in the possible protective effect of their diet, which is made up primarily of fish and related marine foods. This paper reviews the current evidence for reducing the risk of cardiovascular disease with fish-oil supplementation, and discusses related clinical data to support the mechanisms proposed. Included is evidence that fish oil can lower certain serum lipid levels, prolong bleeding time, and reduce systolic blood pressure when consumed in moderately large doses. Information on safety and side effects is also presented, such as a possible increase in serum cholesterol levels and annoying side effects that may severely limit widespread use of this food supplement. Presently it remains unanswered whether fish oil should be recommended as a dietary supplement for the prevention and/or treatment of hypercholesterolemia and associated coronary artery disease. Further research is required to demonstrate a clear reduction in cardiovascular mortality before a uniform recommendation can be made.