Mercury in Fish Raises Heart Attack Risk
posted 11/28/02

Today’s New England Journal of Medicine reports that mercury is associated with increased heart attack risk. In a study of 684 heart attack patients and 724 controls in nine countries, those with the highest measured amounts of mercury (assessed in toenail samples) had more than double the heart attack risk, compared to those with the lowest amounts (odds ratio for highest vs. lowest quintiles = 2.16; 95% CI, 1.09-4.29).

Methylmercury, which comes almost exclusively from consumption of fish, particularly swordfish, shark, tuna, trout, pike, and bass, increases free radical production and lipid peroxidation and may contribute to atherosclerotic progression. While fish oils reduce platelet aggregation (clotting) and appear to have an antiarrythmic effect, which may reduce the likelihood of repeat heart attacks in individuals with narrowed arteries, methylmercury contamination has the opposite effect, increasing heart disease risk.

Here is the reference:

Guallar E, Sanz-Gallardo I, van’t Veer P, et al. Mercury, fish oils, and the risk of myocardial infarction. N Engl J Med 2002;347:1747-54.

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