RESUMO
BACKGROUND: 25-Hydroxy Vitamin D3 is known to have an effect on reproductive system in both genders and may change the semen parameters in men. OBJECTIVE: Our study aimed to evaluate the effect of oral vitamin D3 supplementation on spermogram quantitative and qualitative parameters in infertile men. MATERIALS AND METHODS: This study was a triple-blind randomized controlled trial involving 62 infertile men with impaired spermatogonial tests. They were randomly divided into placebo and D3-supplemented groups. Spermograms and tests for LH (Luteinizing Hormone), FSH (Follicle Stimulating Hormone), TT (Total Testosterone), FT (Free Testosterone), SHBG (Sex Hormone Bonding Globulin), FAI (Free Androgen Index) and vitamin D3 levels were performed before and after the intervention. RESULTS: There were no significant differences between the two groups in parameters of the spermograms or serum levels of LH, FSH, TT, and FAI. In the intervention group, SHBG was significantly decreased after intervention (p = 0.01) and there was a significant increase in FT in the placebo group (p = 0.03). CONCLUSION: The intake of vitamin D3 did not change the quality and quantity of spermograms and serum levels of LH, FSH, TT, and FAI but affected FT and SHBG. Further studies are still needed to clarify the biological role of vitamin D3 on fertility particularly on male fertility. This study lays a foundation for more extensive studies on male infertility.