Fish Oil Flops against Heart Attacks

Another large study of fish oil also failed to show cardiac benefit. Researchers in the Netherlands recruited almost 5,000 patients who had suffered a heart attack. They were randomized to receive either margarine containing low-dose fish oil or placebo margarine, which they used for 40 months. The expectation was that the fish-oil-containing margarine would protect volunteers from repeat heart attacks.
Unfortunately, however, the reduction in heart attacks was not significant. The investigators suggest that perhaps the failure of fish oil to produce significant benefits was due in part to the other medications, such as cholesterol-lowering statin drugs, that nearly all participants were taking. The dose of fish oil was relatively low, at under 400 mg of omega-3 fatty acids daily. Regardless of the explanation, low-dose fish oil does not seem to ward off second heart attacks.

[New England Journal of Medicine, November 18, 2010]