Associations between serum and seminal vitamin D levels and sperm parameters

There were positive correlations between serum vitamin D levels, total progressive motile sperm concentration, and normal sperm morphology. However, serum vitamin D levels were not correlated with seminal vitamin D levels and showed no correlations with potential mechanisms of action, reflected by intracellular calcium and MDA concentrations. Conversely, intracellular calcium levels were positively correlated with both total and progressive sperm motility, suggesting that intracellular calcium plays an essential role in sperm motility.