Excess serum zinc concentration is associated with incident fracture in men: Tehran lipid and glucose study

The relationship between serum zinc (SZn) concentration and fracture risk in men remains poorly understood. The association between serum zinc (SZn) concentration and incidence of bone fracture in men was investigated. Adults men (n = 1968) who had completed data, including SZn concentrations at baseline (2009-2011), were included and followed until March 2018 for the incidence of any fracture requiring inpatients' care. Multivariable Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of fractures across the quartile categories of SZn [Q₁ < 88, Q_2-3 (88-134, as reference), and Q₄≥134 µg/dL], and per one standard deviation (SD) of increased SZn concentration. During a median follow-up period of 8.3 years (interquartile range: 7.7-9.2 years), 2.6% of men (with mean age of 46.8 ± 17.0 years) experienced a new incident fracture. The mean of baseline SZn concentration was 115 ± 38.0 µg/dL. The multivariable-adjusted Cox regression showed that SZn concentrations exceeded the reference range (≥ 134 µg/dL) were associated with an increased risk of fractures with a HR of 2.08 (95% CI = 1.12-3.88). This association was stronger (HR = 2.63, 95% CI = 1.05-6.60) in men aged over 50 years (n = 809). Fracture risk significantly increased by 44% and 74% per one SD increased SZn concentration in all men and in men aged 50 years. Elevated SZn (≥ 134 µg/dL) were associated with a higher risk of fractures in men, especially those aged 50 and above. These findings indicate a potential association between excessive zinc exposure and poorer bone health in men.