Much has been written about the benefits of fish oil for the heart. So it came as a surprise last week when a study published in the Journal of the American Medical Association reported that, contrary to earlier beliefs, taking fish-oil supplements did not reduce the risk of serious abnormal heart rhythms, the kind responsible for sudden cardiac death. You might be tempted to seize on this finding as yet another failure of a popular dietary supplement to protect health. That would be a mistake, because the study is of limited relevance to the general population. The benefits of fish oil are well established, not just for heart health but also for optimum functioning of both body and mind.
Most Americans don't take in enough EPA and DHA to maintain optimum health. There are few dietary sources other than oily fish. Omega-3-fortified eggs, new on the market, contain only small amounts. Walnuts, flaxseed and other vegetarian sources of omega-3 do not provide EPA and DHA but rather a precursor (alpha-linolenic acid) that the body must convert. This conversion is inefficient at best and often inhibited by high intake of the fats common in processed and fast food.
The health-promoting effects of EPA and DHA have little or nothing to do with preventing abnormal cardiac rhythms. Their most important actions are reducing inflammation, reducing the clotting tendency of the blood, improving the profile of fats circulating in the blood, optimizing brain function (DHA is a major constituent of cell membranes in the central nervous system) and inhibiting abnormal cell proliferation, thereby reducing cancer risks. All of this translates into significant disease protection.
The subjects in the J.A.M.A. study had serious heart disease; all had or were about to have defibrillators implanted in their chests to shock their hearts out of episodes of potentially fatal arrhythmias. Two grams of fish oil a day did not reduce the incidence of those episodes or improve death rates. The study was well designed, but even its authors wonder about its significance for healthy people who want to eat right. Not much, to my mind. I take two grams of fish oil a day and recommend that almost everyone do so too.
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