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Omega-3 supplements for the heart

Posted by medconsumers on May 17, 2012

Yet another popular dietary supplement hasn’t lived up to expectations. This time it’s omega-3 fatty acid recommended by many cardiologists for people with heart disease. Unfortunately, these supplements did not help them live longer or avoid a heart attack, stroke, or congestive heart failure. The finding came as a surprise because it failed to confirm the upbeat results of earlier, albeit imperfect, studies.

The reversal is based on an analysis of 14 clinical trials that had a combined total of 20,485 adults with heart disease. All were randomly assigned to take either an omega-3 supplement or a placebo daily; neither the researchers nor the participants knew who was taking the real supplements. The analysis was conducted by Sang Mi Kwak, MD and colleagues in the Korean Meta-analysis Study Group and published in the current issue of Archives of Internal Medicine. Dr. Kwak and colleagues noted that almost all of the trials were funded by pharmaceutical companies that make omega-3 supplements.

What made scientists think omega-3 would do wonders for the heart in the first place? It started in the early 1970s when researchers noticed that the Greenland Eskimos have a low incidence of heart disease. This was assumed to be due to their high consumption of fish or marine mammals that are rich in omega-3 fatty acids.  The animal and population studies that followed eventually zeroed in on two components of omega-3 fatty acids that clearly have healthful effects on the heart: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Then came the above-mentioned randomized clinical trials. Unfortunately, there were problems with the earliest trials. For example, two early trials with results that favored omega-3 supplements had a significant bias in their design because they were open-label trials. In other word, they were not double-blind trials because both the study participants and the researchers conducting the study knew who was taking the real supplement and who was taking the fake. Three trials that came later found no benefit to omega-3, but their results were clouded by the fact that many of the participants in both the supplement and placebo groups were also taking heart disease prevention drugs.

These inconsistent results are the reason for the new analysis by the Korean Meta-analysis Study Group. Its task was to eliminate the poorly designed trials in order to combine the results of the best and most reliable remaining trials. That’s how the group came up with the 14 randomized placebo-controlled, double-blind clinical trials. The flaws, even in these 14 trials, were acknowledged. For example, most did not last very long (less than 2-3 years) and did not have a large number of participants. The study group’s conclusion had carefully chosen wording: There is insufficient evidence of a preventive effect of omega-3 supplements among people with heart disease.

In the commentary that accompanied this analysis, Harvard’s Frank B. Hu, MD, and JoAnn E. Mason, MD, underscored the lack of evidence for supplements, but left the door wide open for a diet high in fatty fish (more than 2 servings of marine fish per week) and plant foods rich in omega-3 fatty acids. They also mentioned a large randomized trial in the works that will determine whether vitamin D and omega-3 supplements protect against cardiovascular disease.   In other words,  stick with foods rich in omega-3 fatty acids … until further notice.      click here

Maryann Napoli, Center for Medical Consumers©
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One Response to “Omega-3 supplements for the heart”

  1. Hernandez Jose A said

    The misconception about homocysteine (Homocysteine-Lowering B Vitamin Therapy) is similar.
    http://jama.jamanetwork.com/article.aspx?volume=299&issue=17&page=2086

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