Fish oil is a rich source of the omega-3 fatty acids DHA and EPA. These essential fats protect your heart in a number of ways. Fish oil can lower your triglycerides and may help increase the elasticity of your blood vessels, lower your blood pressure and stabilize erratic heart beats. Consuming fish oil from supplements or by eating fatty fish may help reduce your risk of dying from heart disease. Consult your physician regarding fish oil if you have had a heart attack to see if it would be beneficial to your course of treatment.
Mechanisms of Action
According to a scientific statement issued in 2003 by the American Heart Association, doses greater than 3 g per day of both DHA and EPA from fish oil can lower your blood triglycerides, a measure of fat in your bloodstream. Supplemental EPA and DHA also lower blood pressure slightly, possibly by enhancing the elasticity of blood vessels, and decrease the ability of your blood to clot around partial blockages in arteries. Another helpful action of DHA and EPA is their ability to alter the porosity of the mineral channels in heart tissue itself. This quality may help stabilize heart arrhythmias, erratic contractions of the heart that can lead to heart attacks.
Fish Oil and Heart Attack Prevention
Increased consumption of fish and fish oil reduces risk of dying from heart disease among large groups of people. A 1997 study utilizing the Chicago Western Electric Study data found that the men who consumed the most fish had the lowest rates of death from heart attack over a 30-year period. Data from the Nurse's Health Study indicates a similar trend for women. A 2002 study in the "Journal of the American Medical Association" reported that women who consumed fish one to three times a month were 21 percent less likely to die from heart disease than those who consumed no fish.
Fish Oil and Heart Attack Treatment
Results from the 1999 GISSI-Prevention Study in Italy, a large clinical trial studying the effects of fish oil supplementation on people who had already suffered a heart attack, demonstrated that taking fish oil after a heart attack significantly reduced the risk of death from a second attack. However, a 2008 review of randomized clinical trials on fish oil supplementation, published in the "British Medical Journal," did not support this finding. This latter study indicated that fish oil did not significantly reduce cardiac arrhythmias or death from heart attack. However, the study did find that fish oil supplementation reduced overall cardiac death rates, a positive effect. If you've already had a heart attack, taking fish oil may lower your risk of dying from heart disease. However, you should ask your doctor about fish oil's effectiveness in relation to other treatments he may prescribe to prevent a second heart attack.
Fish Oil Risks
Fish oil supplements are not without their risks. According to MedlinePlus, taking too much fish oil decreases the ability of your blood to clot and thus increases your risk of bleeding. For this reason, high-dose fish oil supplementation greater than 3 g per day should always be supervised by a medical professional. Fish oil supplementation may also reduce your immune system's ability to fight off infection and should be avoided if you have a weakened immune system. Secondary to the direct action of fish oil is the possibility of environmental contamination. High levels of methylated mercury and PCB, both toxic to humans, concentrate in the bodies of fatty fish. Check if the manufacturer of the fish oil you choose tests its products for environmental contaminants. Molecular distillation is a technique that can remove these contaminants, and you should choose fish oil that has been purified by this process. Also, visit the Natural Resources Defense Council's web page to see which fish are lowest in mercury and other contaminants.
References
- MedlinePlus: Fish Oil
- "The New England Journal of Medicine"; Fish Consumption and the 30-Year Risk of Fatal Myocardial Infarction; M.L. Daviglus et al.; April 1997
- "Lancet"; Dietary Supplementation with n-3 Polyunsaturated Fatty Acids and Vitamin E after Myocardial Infarction: Results of the GISSI-Prevenzione trial; GISSI-Prevenzione Investigators; August 1999
- "British Medical Journal"; Effect of Fish Oil on Arrhythmias and Mortality: Systematic Review; H. Leon et al.; December 2008
- "Arteriosclerosis, Thrombosis, and Vascular Biology"; AHA Scientific Statement: Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease; P.M. Kris-Etherton et al; 2003
- "Journal of the American Medical Association"; Fish and Omega-3 Fatty Acid Intake and Risk of Coronary Heart Disease in Women; F.B. Hu et al.; April 2002
