"Omega-3 fatty acids are not just good fats; they affect heart health in positive ways," says Penny Kris-Etherton, Ph.D., R.D., lead author of the report. They make the blood less likely to form clots that cause heart attack and protect against irregular heartbeats that cause sudden cardiac death.
The comprehensive report examines the health benefits of omega-3 fatty acids in the context of cardiovascular disease (CVD) risk reduction and considers the recent Environmental Protection Agency and the Food and Drug Administration (FDA) guidance about the presence of contaminants in certain species of fish.
Since 2000, the American Heart Association's dietary guidelines have recommended that healthy adults eat at least two servings of fish per week, particularly fish such as mackerel, lake trout, herring, sardines, albacore tuna and salmon. These fish contain two omega-3 fatty acids - eicosapentaenoic and docosahexaenoic acids (EPA and DHA). A third kind is less potent - alpha-linolenic acid and comes from plants, including tofu and other forms of soybeans, canola, walnut and flaxseed and oils made from those nuts and seeds.
People who have elevated triglycerides may need 2 to 4 grams of EPA and DHA per day provided as a supplement. Even the 1 gram/day dose recommended for patients with existing CVD may be more than can readily be achieved through diet alone. These people should consult their physician to discuss taking supplements to reduce heart disease risk. Patients taking more than 3 grams of omega-3 fatty acids from supplements should do so only under a physician's care. The FDA has noted that high intakes could cause excessive bleeding in some people.
Depending on their stage of life consumers need to be aware of both the benefits and risks of eating fish. Children, pregnant and nursing women may be at increased risk of exposure to excessive mercury from fish but also are generally at low risk for CVD. Thus, avoiding potentially contaminated fish is a higher priority for these groups, says Kris-Etherton.
For middle aged and older men, and postmenopausal women, the benefits of eating fish far outweigh the risks within the established guidelines.
"This is hopeful news as we have found that the effects of omega-3 fatty acids on heart disease risk is seen in relatively short periods of time," Kris-Etherton says. "The research shows that all omega-3 fats have cardioprotective benefits, especially those in fish."
Although the mechanisms responsible for omega-3 fatty acids' reduction of CVD risk are still being studied, research has shown:
- Decrease risk of sudden death and arrhythmia.
- Decrease thrombosis (blood clot).
- Decrease triglyceride levels.
- Decrease growth of atherosclerotic plaque.
- Improve arterial health.
- Lower blood pressure.
Co-authors are William S. Harris, Ph.D., and Lawrence J. Appel, M.D., M.P.H.
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