Cross-Sectional Associations of Serum Zinc with Bone Mineral Density in the NHANES 2011-2014 Cohort

This cross-sectional study investigated the association between serum zinc concentrations and total bone mineral density (BMD) using data from 1,674 adults aged ≥ 20 years in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Participants with missing data on key variables were excluded, and analyses accounted for the NHANES complex survey design with 4-year fasting subsample weights (WTSAF4YR). Serum zinc levels were divided into quartiles, and multivariable linear regression models were applied to assess the relationship between serum zinc and total as well as site-specific BMD after adjustment for demographic, anthropometric, lifestyle, and biochemical confounders. Smooth curve fitting and threshold effect analyses based on generalized additive models (GAMs) were used to explore potential nonlinear associations. Serum zinc was positively associated with BMD after adjustment for covariates, with a nonlinear threshold effect observed at approximately 13.20 µmol/L, beyond which the positive association became more pronounced. These findings provide new insight into zinc's role in skeletal health, highlighting that maintaining serum zinc above this level may contribute to optimal bone density and inform strategies for osteoporosis prevention and nutritional assessment.