Association between serum zinc and later development of metabolic syndrome in middle aged and older men: the Kuopio Ischaemic Heart Disease Risk Factor Study

Objective: The aim of this study was to investigate associations of serum zinc with incident metabolic syndrome and its components in middle-aged and older Finnish men. Methods: An 11-y prospective follow-up study conducted among 683 men from the Kuopio Ischaemic Heart Disease Risk Factor Study who were 42 to 60 y old at baseline in 1984 to 1989. The main outcome was incident metabolic syndrome, defined by the National Cholesterol Education Program (NCEP) criteria. Other outcomes were the individual components of the NCEP metabolic syndrome: Fasting blood glucose, serum triacylglycerols, serum high-density lipoprotein (HDL) cholesterol, hypertension, and waist circumference. Results: During the average follow-up of 11 y, 139 men (20.4%) developed metabolic syndrome. Those in the highest tertile of serum zinc had 84% higher risk (95% confidence interval 12 to 201%, P trend across tertiles ¼ 0.015) to develop metabolic syndrome compared with those in the lowest tertile, after adjustment for several potential confounders. The association between serum zinc and incident metabolic syndrome was attenuated by adjustment for waist circumference, serum HDL cholesterol, or hypertension. Serum zinc was also directly associated with higher waist circumference and hypertension and inversely associated with HDL cholesterol at the 11 y examinations. Conclusions: We found a direct association between serum zinc and incidence of metabolic syndrome in middle-aged and older eastern Finnish men. Further studies are warranted to explore the mechanisms.