The Role of Vitamin D in Fertility: Why It Matters for Both Men and Women
VITAMIN D IS ESSENTIAL FOR MUCH MORE THAN JUST BONE HEALTH—ITS IMPACT ON FERTILITY HAS GAINED INCREASING ATTENTION AS STUDIES UNCOVER ITS IMPORTANT ROLE IN REPRODUCTIVE HEALTH.
Known as the “sunshine vitamin” due to its natural production in response to sunlight, vitamin D influences hormone regulation, immune function and cellular processes crucial for both male and female fertility.
Let me break down how vitamin D affects fertility, why deficiencies are common and steps you can take to ensure optimal vitamin D levels if you’re trying to conceive. Note I say optimal levels and not ‘ok’ or ‘adequate’ – I’ll come back to this.
How Vitamin D Impacts Fertility:
Vitamin D acts as both a hormone and a vitamin, regulating critical bodily functions through vitamin D receptors (VDRs), which are present in tissues throughout the body, including reproductive organs. When vitamin D binds to these receptors, it helps control genes associated with fertility.
Female Fertility
In women, vitamin D plays a role in:
Regulating Ovulation: Studies show that optimal levels of vitamin D contribute to regular menstrual cycles and improve ovulation quality. It has been found that vitamin D supports ovarian health, helping follicles mature and release eggs at the right time.
Boosting IVF Success Rates: Women with optimal vitamin D levels tend to have better success rates with in-vitro fertilization (IVF), likely due to vitamin D’s role in the endometrium (the uterine lining). Optimal levels of vitamin D make the endometrium more receptive to embryo implantation.
Reduced risk of reproductive disorders such as polycystic ovary syndrome (PCOS) and endometriosis): PCOS and endometriosis, common causes of infertility in women, have been associated with low levels of vitamin D. While the exact mechanisms are still unclear, vitamin D’s role in hormone regulation may help balance insulin resistance, which is a key factor in PCOS and also seems to have a role in the modulation of inflammation which can be seen in women with endometriosis.
Male Fertility
For men, vitamin D influences fertility through:
Sperm Quality and Motility: Research shows that vitamin D deficiency is linked to lower sperm motility (the ability of sperm to swim effectively), which is crucial for fertilisation. Men with optimal levels of vitamin D often exhibit higher sperm motility and better sperm morphology (shape).
Testosterone Levels: Vitamin D is also linked to testosterone production, which plays a vital role in libido and sperm production. In some studies, men who were supplemented with vitamin D experienced increased testosterone levels, enhancing their overall reproductive health.
Why is Vitamin D Deficiency Common—and Why It Matters:
Vitamin D deficiency is surprisingly common. Key factors include limited sun exposure - particularly in the Winter months, shorter days, reduced sunlight and spending more time indoors decreases the body’s ability to produce enough vitamin D naturally increasing the risk of vitamin D deficiency. Dietary insufficiency and certain medical conditions that interfere with vitamin D absorption are also contributing factors.
For those trying to conceive, deficiency can pose a barrier to successful pregnancy, as highlighted above.
How to Ensure Optimal Vitamin D Levels for Fertility:
If you’re trying to conceive or, ensuring optimal vitamin D levels is a smart step toward improving fertility.
Natural Sources of Vitamin D
Sunlight Exposure: Direct sun exposure remains the most effective way to get vitamin D, though geographic location, skin type and lifestyle can influence how much vitamin D the skin produces. So this one is tough to maintain all year round.
Dietary Sources: While few foods naturally contain vitamin D, some rich sources include fatty fish (such as salmon and mackerel), egg yolks and fortified foods like dairy and plant-based milk.
Vitamin D Supplements
Supplements can be an effective solution, particularly because natural sources can be scarce. But would you know what dose your body needs?
TEST DON’T GUESS!
A simple blood test will give you your current vitamin D status and can either be carried out by your GP or privately for a small cost. Optimal levels are above 75nmol/L, and it’s at this optimal level that vitamin D can do all the jobs it needs to for our body and our fertility. Below this, even if adequate, it will struggle. If you are below 75nmol/L it is best to seek expert advice on how to, not only increase your vitamin D level, but also maintain within optimal range.
Vitamin D and Your Fertility Journey:
The role of vitamin D in fertility is compelling, with substantial evidence showing its importance for both men and women. By maintaining optimal vitamin D levels, you can support hormone regulation, boost reproductive health and improve your chances of a successful pregnancy.
If you’re planning to conceive, consider getting your vitamin D levels checked. I offer full interpretation of your test results so please do get in touch if you’d like to investigate further.
Any questions or concerns please don’t hesitate to contact me.
REFERENCES
Abu-Zaid, A., Saleh, S. A. K., Adly, H. M., Baradwan, S., Alharran, A. M., Alhatm, M., Alzayed, M. M., Alotaibi, M. N., Saad, A. R., Alfayadh, H. M., Abuzaid, M., & Alomar, O. (2024). The Impact of Vitamin D on Androgens and Anabolic Steroids among Adult Males: A Meta-Analytic Review. Diseases (Basel, Switzerland), 12(10), 228. https://doi.org/10.3390/diseases12100228
Dragomir, R. E., Toader, O. D., Gheoca, D. E., & Stănculescu, R. V. (2024). The Key Role of Vitamin D in Female Reproductive Health: A Narrative Review. Cureus. https://doi.org/10.7759/cureus.65560
Grundmann, M., & von Versen-Höynck, F. (2011). Vitamin D - roles in women’s reproductive health? Reproductive Biology and Endocrinology, 9(1), 146. https://doi.org/10.1186/1477-7827-9-146
Holzer, M., Massa, E., & Ghersevich, S. (2022). Relationship between serum vitamin D concentration and parameters of gonadal function in infertile male patients. Current Urology, Publish Ahead of Print. https://doi.org/10.1097/cu9.0000000000000075
Qiu, Y., Yuan, S., & Wang, H. (2020). Vitamin D status in endometriosis: a systematic review and meta-analysis. Archives of Gynecology and Obstetrics, 302(1), 141–152. https://doi.org/10.1007/s00404-020-05576-5
Trummer, C., Pilz, S., Schwetz, V., Obermayer-Pietsch, B., & Lerchbaum, E. (2018). Vitamin D, PCOS and androgens in men: a systematic review. Endocrine Connections, 7(3), R95–R113. https://doi.org/10.1530/EC-18-0009