The synergistic effects of vitamin D and estradiol deficiency on metabolic syndrome in Chinese postmenopausal women

Objective: Recent studies show that vitamin D (VitD) deficiency is associated with metabolic syndrome (MetS). Current evidence suggests that estrogen and VitD have similar physiological functions and potentially interact with bone health. We investigated the association between estradiol (E-2) and 25-hydroxyvitamin-D [25(OH)D] with MetS and its components in Chinese postmenopausal women. Methods: In this cross-sectional study, we examined 616 postmenopausal women (aged 49-86 y) from southern China who were not taking estrogen and VitD/calcium supplements. At the end of data collection, serum E-2 and 25(OH)D were measured for each participant. MetS was defined according to the 2006 International Diabetes Federation standard. Results: There was a positive correlation between 25(OH)D and E-2. Higher 25(OH)D was associated with a favorable lipid profile, blood pressure, and glucose level. E-2 was negatively associated with cholesterol, triglycerides, and blood pressure. The odds ratio for MetS was 2.19 (95% CI, 1.19-4.01, P value for trend=0.009) for deficient compared with sufficient women after multivariable adjustment. This association remained unchanged after further adjusting for E-2 levels. After stratified analysis by VitD status, low E-2 increased MetS risk in women with VitD deficiency (odds ratio = 3.49, 95% CI, 1.45-8.05 for the lowest vs the highest tertile). Conclusions: These results suggest a synergistic role of VitD and E-2 deficiency in MetS in Chinese postmenopausal women.