Homeostatic relevance of vitamin D in maintaining male fertility in human: Down–regulation of oxidative stress and up-regulation of anti-oxidative defense and steroidal hormones

Assessment of serum vitamin D level and seminal vitamin D receptor gene methylation in a sample of Egyptian men with idiopathic infertility

Vitamin D deficiency has been linked with different health problems including male infertility. Its function is mediated by the vitamin D receptor, which acts as a transcription factor. Epigenetic mechanisms such as DNA methylation may affect the vitamin D receptor gene and result in gene silencing. The present study aimed to assess serum vitamin D level and seminal methylation of vitamin D receptor gene in idiopathic male infertility. Blood and semen samples were collected from 60 men with idiopathic infertility and 40 healthy fertile men. Vitamin D levels were detected using enzyme-linked fluorescent assay technique and methylation status was assessed by methylation-specific PCR. Results revealed that serum levels of 25OHD were significantly lower in patients compared to controls. Positive correlation was found between serum level of 25OHD and sperm concentration in patients group and progressive motility in total studied group. Methylation of vitamin D receptor gene was significantly higher in patients compared to control group. Negative correlation was found between methylation of vitamin D receptor gene and both sperm concentration and progressive motility in total studied group. Results of the present study suggest that vitamin D deficiency and vitamin D receptor gene methylation may be involved in aetiopathogenesis of idiopathic male infertility.

The association between serum vitamin D, fertility and semen quality: A systematic review and meta-analysis

PURPOSE

A number of studies have examined the association between vitamin D, fertility and semen quality, however, findings have been inconclusive. Herein, we systematically reviewed available observational studies to elucidate the overall relationship between vitamin D, fertility and semen quality in adult population.

METHODS

PubMed, Cochrane's Library, Science Direct, Scopus, Google Scholar and ISI Web of Science databases were searched until December 2018 for all available studies evaluating the association between vitamin D, fertility and semen quality. The Newcastle-Ottawa Quality Assessment Scale was used to examine the quality of each study.

RESULTS

A total of 18 studies out of 1843 met our inclusion criteria and were included in our systematic review and meta-analysis. Serum 25(OH)D3 was significantly higher in fertile subjects compared to infertile ones (WMD -0.63; 95% CI, -1.06 to -0.21; P = 0.003). Furthermore, there was a significant association between serum 25(OH)D, sperm motility (WMD -5.84; 95% CI, -10.29 to -1.39; P = 0.01) and sperm progressive motility (WMD -5.24; 95% CI, -8.71 to -1.76; P = 0.003).

CONCLUSION

Our findings add to the existing literature supporting the concept that nutrition, especially vitamin D, plays an important role in men's sexual health. It should be noted that because of significant heterogeneity among the included studies, caution is warranted when interpreting the results. Further well-designed prospective cohort studies and clinical trials are needed for better understanding of the relationship between vitamin D and fertility and its components.