Myocardial infarction risk in relation to zinc concentration in toenails

Zn is an essential mineral. The role of Zn in atherosclerosis is not clear. Epidemiological studies, which have reported contradictory results, are limited by the use of serum Zn levels as a marker of intake. We assessed the association of toenail Zn, which integrates dietary Zn intake over 3 to 12 months, with the risk of a first myocardial infarction. Toenail Zn concentrations were determined by neutron activation analysis in the European multi-centre case-control study on antioxidants, myocardial infarction and breast cancer. This multi-centre case-control study included 684 cases and 724 controls from eight European countries and Israel. Toenail Zn levels of controls (adjusted for age and study centre) were positively associated with age, (alpha)tocopherol and Se, but not with additional dietary variables or with classical risk factors for CHD. Average toenail Zn was 106·0 mg/kg in cases (95 % CI 103·1, 108·9) and 107·5 mg/kg in controls (95 % CI 104·5, 110·7). After controlling for cardiovascular risk factors and for centre, the adjusted odds ratios of myocardial infarction for quintiles 2-5 of toenail Zn with respect to the first quintile were 0·97 (95 % CI 0·59, 1·58), 1·15 (95 % CI 0·72, 1·85), 0·91 (95 % CI 0·56, 1·50), and 0·85 (95 % CI 0·52, 1·39). The P for trend was 0·45. In conclusion toenail Zn levels (reflecting long-term dietary intake) were not significantly associated with acute myocardial infarction.