Zinc supplementation can protect from enhanced risk of femoral neck fracture in male rats chronically exposed to cadmium.

The aim of this study was to evaluate whether zinc (Zn) supplementation can protect from an enhanced risk of femoral neck fracture due to chronic exposure to cadmium (Cd). For this purpose, biomechanical properties of the neck and bone mineral density (BMD) at the proximal femur of rats receiving Cd (5 or 50mg/l) or/and Zn (30 or 60 mg/l) in drinking water for 6 and 12 months were evaluated. The exposure to 5 and 50mg Cd/l decreased the proximal femur BMD and affected biomechanical properties of the femoral neck. In the rats treated with 5mg Cd/l, weakening of the femoral neck strength was observed after 12 months, whereas at higher exposure--already after 6 months. The supplementation with 30 and 60 mg Zn/l, enhancing its daily intake by 68% and 138%, respectively, compared to the standard diet, had beneficial influence on the femoral neck biomechanical properties during the exposure to Cd, but it had no impact on the proximal femur BMD. Zn administration during the 12-month exposure to 5mg Cd/l totally prevented the weakening of the neck. Zn supplementation during the 6-month treatment with 50mg Cd/l entirely prevented the Cd-induced decrease in the neck fracture strength; however, at the longer exposure to Cd the protective effect of Zn was only partial. The beneficial Zn influence was independent on its dose. The results allow the conclusion that an increase in the daily intake of Zn during moderate and relatively high exposures to Cd can reduce femoral neck susceptibility to fracture. Based on the findings, it seems that enhanced Zn consumption in subjects chronically exposed to Cd may, at least partly, protect from the enhanced risk of femoral neck fracture.