Association between vitamin D and bisphenol A levels in an elderly Italian population: results from the InCHIANTI study

Objective This study aimed to evaluate the association between the endocrine-disrupting chemical, bisphenol A (BPA) on circulating levels of 25-hydroxy vitamin D (25(OD)D) and other vitamin D metabolites in an elderly population in Italy. Methods This was a retrospective analysis of the InCHIANTI Biobank in Italy. The association between vitamin D metabolites namely 1,25(OH)D, 25(OH)D, parathyroid hormone (PTH) and BPA levels were evaluated. Multiple regression models were used to examine the association between predictor variables with 1,25(OH)D or 25(OH)D levels. Results Samples from 299 individuals aged 72.8 ± 15.7 years were examined. Mean levels of BPA, 1,25(OH)D and 25(OH)D were 351.2 ± 511.6 ng/dL, 43.7 ± 16.9 pg/mL and 20.2 ± 12.1 ng/mL, respectively. One hundred eighty individuals (60.2%) were deficient (<20 ng/mL) in 25(OH)D and this population also presented higher BPA levels (527.9 ± 1289.5 ng/dL vs 86.9 ± 116.8 ng/dL, P  < 0.0001). Univariate analysis revealed that BPA levels were negatively correlated with both 1,25(OH)D (r= −0.67, P  < 0.0001) and 25(OH)D (r= −0.69, P  < 0.0001). Multivariate regression revealed that PTH (β: −0.23, 95% CI: −0.34, −0.13, P  < 0.0001) and BPA (β: −0.25, 95% CI: −0.3, −0.19, P  < 0.0001) remained significantly associated with 25(OH)D levels while BPA was also associated with 1,25(OH)D levels (β: −0.19, 95% CI: −0.22, −0.15, P  < 0.0001). Receiver operating characteristic curve analysis showed that a BPA concentration of >113 ng/dL was the best cut-off to predict individuals deficient in 25(OH)D (area under the curve: 0.87, 95% CI: 0.82–0.90, P  < 0.0001). Conclusion The strong negative association between BPA and vitamin D in this elderly population warrants further investigation, particularly since this population is already at greatest risk of hypovitaminosis and fracture.