Harvard Heart Letter

Refining the prescription for fish oil

Fish oil may not help those with implanted defibrillators.

Omega-3 fatty acids are a big reason why fish is extolled as a heart-healthy food. Yet research showing that fish oil doesn't seem to help people with an implantable cardioverter/defibrillator (ICD) suggests that the benefits of omega-3s might not extend to everyone.

Our bodies can't make omega-3 fats. Oily fish such as salmon, sardines, herring, and mackerel are good sources of two omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A third, alpha-linolenic acid (ALA), comes from plants, especially flaxseed, walnuts, soybeans, and canola oil. Only 10% to 15% of ALA is converted to the more powerful omega-3s; the rest is burned for energy.

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