A recent study published by the journal Reproductive Biology and Endocrinology found that vitamin D status is linked with male reproductive success in couples attempting pregnancy.
Human infertility occurs when a couple is unable to achieve a pregnancy after twelve months of carefully prepared unprotected sexual intercourse. Up to 15% of the population is infertile, affecting both men and women equally.
Vitamin D deficiency has been linked with several reproductive disorders, including miscarriage, preterm birth and hypogonadism. In fact, research has discovered that vitamin D may play a regulatory role in reproductive physiology. Since vitamin D receptors and enzymes are expressed in the ovaries, placenta, testis and male reproductive tract, researchers hypothesized that vitamin D may act locally to mediate the effects on the reproductive system. In animal models, vitamin D deficiency in males has been found to result in low sperm count, impaired sperm motility and decreased pregnancy rates.
Despite the prevalence of male infertility, as well as the established link between vitamin D status and male fertility in animal models, there is a lack of research regarding vitamin D in male partners of couples attempting pregnancy. Therefore, researchers recently conducted a pilot study to evaluate whether vitamin D deficiency in males may reduce the rate of conception in couples attempting pregnancy.
A total of 102 couples enrolled in the study. The couples were separated into two groups, depending on the vitamin D status of the male partners. Group 1 was considered vitamin D sufficient (≥30 ng/ml) and group 2 had low vitamin D levels (<30ng/ml). All males in the study had their semen analyzed based on the World Health Organization’s (WHO) reference criteria. The female partners in groups 1 and 2 received 3 consecutive cycles of gonadotropin-induced mono-ovulation, a common procedure used to increase conception rate.
After observing the patients for three months, the researchers found that the pregnancy rates were significantly elevated in couples with normal vitamin D levels (p< 0.05). However, the semen analysis concluded that the sperm concentration, motility and form remained similar in both groups, regardless of vitamin D status.
The researchers concluded,
“Taken together, the results from our pilot study suggest the existence of a direct relationship between male vitamin D serum levels and semen ability to begin a pregnancy during cycles of timed vaginal intercourse.”
The authors theorized that the lack of significant findings regarding the difference in semen quality among the two groups is simply due to the limitations of routine semen analysis, such as not accounting for immature chromatin, fragmented DNA and sexual activity.
Although the researchers successfully confirmed their hypothesis, there are a couple of limitations to note. First, the observational study design only proves association, not causality. Also, the small sample size decreases the strength of their findings. Future large scaled clinical trials are needed to determine if vitamin D supplementation may improve the rate of successful pregnancy in couples undergoing mono ovulation therapy.
If you are a couple who have had difficulty conceiving, we recommend supplementing with 5,000 IU/day of vitamin D3. What have you got to lose?
Sturges, M. & Cannell, JJ. Does low vitamin D status reduce male fertility? The Vitamin D Council Blog & Newsletter, December 8, 2015.
Tartagni, M. et al. Males with low serum levels of vitamin D have lower pregnancy rates when ovulation induction and timed intercourse are used as a treatment for infertile couples: results from a pilot study. Reproductive Biology and Endocrinology, 2015.