Is there a relationship between serum vitamin D and semen parameters? A cross-sectional sample of the Iranian infertile men.

BACKGROUND Recent studies suggest that serum vitamin D may be associated with semen parameters. In the present cross-sectional study, we attempted to investigate the association between serum vitamin D levels and semen parameters among Iranian sub-fertile men. RESULTS A total of 350 infertile men recruited for this cross-sectional study using a simple random sampling method with a mean age of 34.77 years old, body mass index of 26.67 kg/m2, serum vitamin D of 20.17 ng/ml, semen volume of 3.82 mL, sperm count of 44.48 (106/mL), sperm total motility of 38.10 %, and morphologically normal sperm of 7.0 %. After controlling for potential confounders, serum vitamin D was positively associated with semen volume (β = 0.63, 95 % CI: 0.06, 1.20), sperm count (β = 14.40, 95 % CI: 4.56, 24.25), sperm total motility (β = 18.12, 95 % CI: 12.37, 23.86), and sperm normal morphology (β = 1.95, 95 % CI: 1.07, 2.83). CONCLUSIONS The present findings suggest that higher serum vitamin D levels are positively associated with higher semen volume, sperm count, sperm total motility, and normal morphology rate. These findings, however, do not specify a cause-and-effect relationship, and there is a need for further research in this area to understand whether vitamin D supplementation can improve semen parameters.