Sidebar: Mercury, Antimony and Idiopathic Dilated Cardiomyopathy

Maybe you’ve heard stories of high-school athletes who suddenly drop dead of a heart attack while training or competing. Although seemingly healthy before the heart attack, these athletes have a serious heart disease known as idiopathic dilated cardiomyopathy (IDCM). Idiopathic means that physicians do not know what causes the pathology and that it appears to be unique (i.e., very different from the kinds of heart disease that are common in older individuals).

Two years ago, Italian researchers discovered a striking difference between 1) IDCM hearts, 2) those of other cardiovascular diseases, and 3) superficially healthy hearts [Frustaci et al., 1999]. That difference was a many thousand-fold increase in mercury and antimony levels. Here are their data, arranged by the A-group-to-C-group ratio:

The normal level of mercury that would be expected to be found in heart tissue would be less than 500 ng/g (nanograms per gram of wet tissue). And more often than not, mercury levels are less than 50 ng/g. A nanogram (10^-9 g) is one thousandth of a microgram (10^-6 g), which is one thoudsandth of a milligram (10^-3 g), which is one thousandth of a gram (10^0 g). So 50 ng/g is less than a thousandth of a thousandth of one percent, a very small amount in absolute terms.

Of thirteen living ICDM patients, the average mercury level in their heart muscle biopsies was 178,400 ng/g! That’s many hundreds of times higher than 500 ng/g, and many thousands of times higher than the levels found in non-IDCM hearts. The lowest mercury level was 9,300 ng/g, which is still far in excess of any normal expectation. The highest was 865,000 ng/g, which is actually approaching 1 mg/g (i.e., one tenth of one percent)! It seems a miracle that these people were actually alive with so much mercury in their hearts.

Although cardiac mercury levels are phenomenally high, levels of mercury in biopsies of leg muscle were within the normal range. So this mercury accumulation phenomenon of IDCM seems to be quite specific for the heart muscle.

Where does the mercury come from? The researchers were unable to find any occupational or environmental sources of exposure for any of the people tested. Therefore, it seems likely that it comes from ordinary foods and dental amalgams.

Why does it concentrate to such an extreme degree? One possibility is a focal infection in the heart muscle. Some researchers have suggested that viral infections might underlie IDCM. Coxsackie virus infections have been reported to increase nickel and mercury levels in mouse hearts [Ilback et al., 1995]. And anaerobic bacteria can catabolize cysteine and methionine into hydrogen sulfide and methylthiol, which can bind to mercury, enhance its ability to penetrate membranes, and dramatically increase its toxicity [Haley, 2001].

Why isn’t such a massive mercury level unequivocally lethal? No one yet knows why, but the heart muscle must have an extraordinary capacity for mercury detoxification.

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References

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A Frustaci, N Magnavita, C Chimenti, M Caldarulo, E Sabbioni, R Pietra, C Cellini, G F Possati and A Maseri. Marked elevation of myocardial trace elements in idiopathic dilated cardiomyopathy compared with secondary cardiac dysfunction. J Am Coll Cardiol 33: 1578-83, 1999.