Background: Activated Vitamin D regulates testosterone (T) and estradiol (E2) synthesis. 25-hydroxyvitamin D [25(OH)D] deficiency has been associated with low T levels in men with conflicting associations described in women. Low 25(OH)D is associated with increased cardiovascular (CVD) risk and possibly with erectile dysfunction (ED) in men. We examined the association of 25(OH)D with sex hormones (SH) in men and women and with ED in men in a multi-ethnic cohort (mean age 63 yrs).
Methods: 25(OH)D,T, E2, dehydroepiandrosterone (DHEA), and SH binding globulin (SHBG) levels were measured at MESA exam 1 (2000-2002), and bioavailable T calculated. Self-reported ED was recorded at exam 5 (2010-2012). Using linear regression, we evaluated the multivariable adjusted cross-sectional associations of 25(OH)D and SH separately by sex. Among men, we used logistic regression to assess the association of 25(OH)D with odds of low T<10.41 nmoI/L (300 ng/dl) [9.4%] at exam 1 and with ED at exam 5.
Results: After adjusting for demographic and lifestyle variables, higher 25(OH)D levels were associated with greater total T and SHBG in men and with greater E2, SHBG, and lower bioavailable T and DHEA in women [Table]. Compared to ≥30 ng/ml, 25(OH)D deficiency (<20 ng/ml, 31% men and 32% women) was associated with increased odds of low T in men in age/race model [1.37 (1.05, 1.77)] but was attenuated after adjusting for lifestyle variables [1.19 (0.91, 1.55)]. Among 1796 men with 25(OH)D and T at exam 1, 45% were found to have ED at exam 5. Neither 25(OH)D deficiency nor low T was associated with ED. In all analyses, results were similar after further adjusting for CVD risk factors.
Conclusion: Higher 25(OH)D levels were associated with higher SHBG in both men and women, greater T in men, and greater E2 and lower DHEA in women independent of adiposity and lifestyle. 25(OH)D deficiency and low T were not associated with prevalent self-reported ED assessed 10 years later. Future studies are needed to determine if treating low vitamin D can influence sex hormone levels.