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Omega-3 in fish: How eating fish helps your heart

The omega-3 fatty acids in fish are good for your heart. Find out why the heart-healthy benefits of eating fish usually outweigh any risks.

By Mayo Clinic staff

If you're worried about heart disease, eating one to two servings of fish a week could reduce your risk of dying of a heart attack by a third or more.

Doctors have long recognized that the unsaturated fats in fish, called omega-3 fatty acids, appear to reduce the risk of dying of heart disease. For many years, the American Heart Association has recommended that people eat fish rich in omega-3 fatty acids at least twice a week.

But some people are still concerned about mercury or other contaminants in fish outweighing its heart-health benefits. However, when it comes to a healthier heart, the benefits of eating fish usually outweigh the possible risks of exposure to contaminants. Find out how to balance these concerns with adding a healthy amount of fish to your diet.

What are omega-3 fatty acids, and why are they good for your heart?

Fish contain unsaturated fatty acids, which, when substituted for saturated fatty acids such as those in meat, may lower your cholesterol. But the main beneficial nutrient appears to be omega-3 fatty acids in fatty fish. Omega-3 fatty acids are a type of unsaturated fatty acid that's thought to reduce inflammation throughout the body. Inflammation in the body can damage your blood vessels and lead to heart disease.

Omega-3 fatty acids may decrease triglycerides, lower blood pressure, reduce blood clotting, boost immunity and improve arthritis symptoms, and in children may improve learning ability. Eating one to two servings a week of fish, particularly fish that's rich in omega-3 fatty acids, appears to reduce the risk of heart disease, particularly sudden cardiac death.

Does it matter what kind of fish you eat?

Fatty fish, such as salmon, herring and to a lesser extent tuna, contain the most omega-3 fatty acids and therefore the most benefit, but many types of seafood contain small amounts of omega-3 fatty acids.

Most freshwater fish have less omega-3 fatty acids than do fatty saltwater fish. Some varieties of freshwater trout have relatively high levels of omega-3 fatty acids.

Are there any kinds of fish you should avoid?

Some fish, such as tilapia and catfish, don't appear to be as heart healthy because they contain higher levels of unhealthy fatty acids. Keep in mind that any fish can be unhealthy depending on how it's prepared. For example, broiling or baking fish is a healthier option than is deep-frying.

Some researchers are concerned about eating fish produced on farms as opposed to wild-caught fish. Researchers think antibiotics, pesticides and other chemicals used in raising farmed fish may have harmful effects to people who eat the fish.

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References
  1. Fish and omega-3 fatty acids. American Heart Association. http://www.americanheart.org/presenter.jhtml?identifier=4632. Accessed Oct. 7, 2010.
  2. Chattipakron N, et al. Cardiac mortality is associated with low levels of omega-3 and omega-6 fatty acids in the heart of cadavers with a history of coronary heart disease. Nutrition Research. 2009;29:696.
  3. Levitan EB, et al. Fish consumption, marine omega-3 fatty acids, and incidence of heart failure: A population-based prospective study of middle-aged and elderly men. European Heart Journal. 2009;30:1495.
  4. Farzaneh-Far R, et al. Association of marine omega-3 fatty acid levels with telomeric aging in patients with coronary heart disease. Journal of the American Medical Association. 2010;303:250.
  5. Weaver KL, et al. The content of favorable and unfavorable polyunsaturated fatty acids found in commonly eaten fish. Journal of the American Dietetic Association. 2008;108:1178.
  6. Hanwell HEC, et al. Acute fish oil and soy isoflavone supplementation increase postprandial serum (n-3) polyunsaturated fatty acids and isoflavones but do not affect triacylglycerols or biomarkers of oxidative stress in overweight and obese hypertriglyceridemic men. Journal of Nutrition. 2009;139:1128.
  7. What you need to know about mercury in fish and shellfish. U.S. Food and Drug Administration and Environmental Protection Agency. http://www.epa.gov/waterscience/fish/files/MethylmercuryBrochure.pdf. Accessed Oct. 7, 2010.
  8. Philibert A, et al. Fish intake and serum fatty acid profiles from freshwater fish. American Journal of Clinical Nutrition. 2006;84:1299.
  9. Cole DW, et al. Aquaculture: Environmental, toxicological and health issues. International Journal of Hygiene and Environmental Health. 2009;212:369.
HB00087 Dec. 21, 2010

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