Objective: Cross-sectional studies in the Caucasian population have shown a significant relationship between vitamin D and testosterone levels, but data in the Asian population are limited. This study aimed to determine the association between vitamin D and testosterone levels in Malaysian men.
Methods: Chinese and Malay men (n = 382) aged 20 years or above residing in the Klang Valley, Malaysia were recruited. Their fasting blood was collected for serum testosterone, sex hormone-binding globulin (SHBG) and 25-hydroxyvitamin D (25(OH)D) assays. Relationship between 25(OH)D and testosterone levels was analyzed using multiple regression analysis. Testosterone and SHBG levels among subjects with different vitamin D status were compared using univariate analysis. Confounders such as age, ethnicity and body mass index (BMI) were adjusted.
Results: 25(OH)D was significantly and positively associated with total testosterone and SHBG levels before and after adjustment for age and ethnicity (p < 0.05). Only association with SHBG remained significant after further adjustment for BMI (p < 0.05). Total testosterone and SHBG values displayed an increasing trend from subjects with vitamin D deficiency to those with optimal level (p < 0.05). The trend was attenuated after adjustment for BMI (p > 0.05).
Conclusion: 25(OH)D is significantly associated with total testosterone and SHBG in Malaysian men but this association is BMI-dependent.
Keywords: Men; sex hormone-binding globulin; testosterone; vitamin D.