What are omega-3 fatty acids?

Omega-3 fatty acids include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish, and alpha-linolenic acid, found in soy, canola oil, flaxseed, and English walnuts.

For what conditions are omega-3 fatty acids effective?

There is good evidence that omega-3 fatty acids, particularly EPA and DHA, prevent heart disease. In people who already have heart disease, they help prevent death, heart attack, and stroke. They also reduce triglycerides. Omega-3 fatty acids might also help rheumatoid arthritis, high blood pressure, depression, bipolar disorder, menstrual pain, and certain kidney problems.

What is the best source of omega-3 fatty acids?

The best source of omega-3 fatty acids is fatty fish, like salmon. The American Heart Association (AHA) recommends that everyone eat at least two fatty fish meals (baked or broiled) weekly for cardiovascular health. People who have heart disease should try to eat fatty fish daily. Also add foods rich in alpha-linolenic acid (canola oil, soy, English walnuts, flaxseed) to your diet. But they are not good substitutes for fish because they do not provide enough EPA/DHA. Fish oil capsules are a convenient way to get your omega-3 fatty acids, especially if you need high doses. Fish oil capsules are sold over-the-counter or by prescription (Lovaza [formerly Omacor] in U.S.). Ask your healthcare provider if fish oil capsules are right for you.

Should I be concerned about mercury in fish?

Women who are pregnant or may become pregnant or are breastfeeding, and young children are at risk of mercury toxicity from certain fish. The EPA (U.S.) and Health Canada have specific recommendations for which fish these at-risk persons should avoid or limit. Fish low in mercury include shrimp, canned light tuna (not albacore), salmon, pollock, and catfish. Fish oil capsules are generally low in mercury and other pollutants. For more information, see http://www.epa.gov/waterscience/fishadvice/advice.html (U.S.) http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/environ/mercur/cons-adv-etud-eng.php. (Canada).

How do I choose a fish oil product?

Over-the-counter fish oil is considered a supplement, not a drug, so quality and content varies. Choose products with the "USP Verified Mark" on the label. These have been tested, and have acceptable levels of mercury, other heavy metals, PCBs, and dioxins. They are confirmed to contain what the label says they contain. The omega-3 content is the labeled amount of DHA plus EPA.

If taking fish oil to treat high triglycerides, ask your healthcare professional about Lovaza [formerly Omacor], an FDA-approved prescription fish oil product. It is expensive, but some health insurance plans may cover part of the cost. It is a concentrated form of fish oil, so fewer capsules are needed to get the same amount of fish oil provided in over-the-counter capsules.

Are there side effects or drug interactions with omega-3 fatty acids?

Fish oil can cause nausea, heartburn, or loose stool. It can have a fishy aftertaste. Some patients have found that refrigerating or freezing fish oil supplement capsules might help. (Prescription Lovaza should NOT be frozen.) Discard capsules with a very strong or spoiled taste. There is a small increased risk of bleeding or bruising when taking fish oil at doses greater than 3 grams daily. Check with your healthcare provider if you are taking aspirin, warfarin (Coumadin), or clopidogrel (Plavix).

Who should not take omega-3 fatty acid supplements?

High doses of alpha-linolenic acid may increase the risk of prostate cancer, so supplements should be avoided in men with prostate cancer or at risk of prostate cancer. If you are allergic to fish, get approval from your healthcare provider before taking fish oil capsules.