Impact of Vitamin D3 Supplementation on Androgens and Semen Parameters in Infertile Men: A Systematic Review and Meta-Analysis Based on Prospective Randomised Controlled Trials.

Objective: This study aims to investigate the effects of vitamin D₃ supplementation on androgen levels and semen parameters in infertile men.

Methods: A comprehensive literature search was conducted across multiple databases, including PubMed, Web of Science, Cochrane Library, Scopus and Embase, to identify studies investigating the effects of vitamin D₃ supplementation on androgen levels and semen parameters in infertile males. Data pertaining to changes in testosterone, sex hormone-binding globulin (SHBG), total sperm count and percentage of motile sperm before and after intervention were extracted and analysed.

Results: Six studies, involving 945 subjects, were included in the quantitative analysis. With regard to testosterone levels, vitamin D₃ supplementation was found to increase testosterone, although this change was not statistically significant (standard mean difference (SMD) = 0.07, 95% confidence interval (CI): -0.11, 0.25). Similarly, an increase in SHBG levels was observed after vitamin D₃ supplementation, but the change was not statistically significant (SMD = 0.42, 95% CI: -0.38, 1.22). By contrast, an increase in total sperm count was observed (SMD = 1.04, 95% CI: 0.11, 2.19). Additionally, vitamin D₃ supplementation significantly increased the percentage of motile sperm (SMD = 0.82, 95% CI: 0.00, 1.64).

Conclusions: In infertile men, vitamin D₃ supplementation does not significantly affect androgen levels. Nevertheless, it may contribute to improvements in total sperm count and the percentage of motile sperm, potentially enhancing reproductive function.