Vitamin D may contribute to ‘optimal sperm function’
MedWire News: Vitamin D levels could affect the functionality of sperm, show the results of a Danish study.
The presence of activated vitamin D (I,25[OH]2D3) in human sperm increased intracellular calcium concentration and sperm motility, and vitamin D serum levels were positively associated with sperm motility, report the researchers.
The study was conducted on healthy men, and therefore is not sufficient to determine whether vitamin D supplements may improve sperm quality in infertile men, said lead author Martin Blomberg Jensen (University Department of Growth and Reproduction, Copenhagen).
"However, it uncovers some of the functions of vitamin D and generates new hypotheses," he added.
Jensen and colleagues investigated the effect of vitamin D on markers of sperm function using data for 300 men in the general population. The men gave sperm and blood samples, and completed a comprehensive questionnaire concerning demographic and medical information.
A total of 44% of the men had insufficient vitamin D levels (<50 nM).
The researchers hypothesized that, in light of previous observations in rat models, vitamin D deficiency would worsen sperm quality.
Sample analysis revealed positive correlations between serum vitamin D levels and all semen variables, although results were only significant for progressive motility and total motility, notes the research team in the journal Human Reproduction. Conversely, serum vitamin D was inversely correlated with parathyroid hormone levels.
Specifically, men with vitamin D deficiency (<25nM) had a significantly lower proportion of motile, progressive motile, and morphologically normal sperm compared with men with high vitamin D levels (>75 nM).
The group also found a positive correlation between calcium levels and both progressive and total sperm motility. Activated vitamin D increased intracellular calcium concentration, sperm motility, and induced the acrosome reaction in in vitro sperm samples from a subgroup of 40 men, which indicates that "vitamin D may be involved in the induction of motility," write Jensen et al.
After adjustment for potential confounding factors, including duration of abstinence, season, and any medication, these associations remained and indeed the significance level increased for motility.
Co-author Anders Juul (University of Copenhagen) concluded: "Low semen quality may have numerous cases, but it often has a fetal origin similar to some male genital malformations and testicular cancer. However, this study indicates that factors in adult life may also play a role for semen quality."
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By Sarah Guy