Optimal Vitamin D Status in a Middle-Aged and Elderly Population Residing in Shanghai, China.

BACKGROUND The aim of this study was to investigate the optimal vitamin D status in the middle-aged and elderly population residing in Shanghai, China. MATERIAL AND METHODS A total of 1,829 males and postmenopausal females older than 45 years of age in the Changfeng community of Shanghai were included in this study. The optimal vitamin D level was determined according to the suppression of parathyroid hormone (PTH) and the highest bone mineral density (BMD). Locally weighted scatter plot smoothing (LOWESS) was performed to study the correlations of 25(OH)D with PTH and BMD in the lumbar spine and total hip, adjusting for gender, age, weight, use of calcium and vitamin D supplements, eGFR, smoking status, and alcohol consumption. RESULTS The mean serum 25(OH)D concentration was 48.0±19.2 nmol/L for the whole study population. The circulating PTH was maximally suppressed by the serum 25(OH)D of 55 nmol/L in the total population (60 nmol/L for males and 50 nmol/L for females). The 25(OH)D concentrations corresponding to the highest BMD at lumbar spine (L1-L4) and total hip were 53 nmol/L and 75 nmol/L, respectively, for the whole population. These values were also higher in males than females. CONCLUSIONS The optimal 25(OH)D concentration of 55 nmol/L is sufficient to maintain the bone health and metabolic status in middle-aged and elderly individuals living in Shanghai. Males probably need higher vitamin D concentration than females. There are differences between vitamin D status based on lumbar spine BMD and total hip BMD.