Could this vitamin boost fertility during summer?

As you probably know (if you paid attention during school geography lessons), folk living in the Northern American and European continents don’t get to enjoy as much sunlight as we do. They have bitterly cold winters where it’s dark even before the working day ends. No-one spends too much time outside from day to day, and when they do, as little skin as possible is exposed to the bitter weather. Researchers studying fertility of women in areas with these long winters have noticed an interesting trend: a spike in conception rates during summer. Coincidentally, this is when everyone gets more sun exposure. Blood tests confirmed that the vitamin D levels of women rose during summer and dipped during winter. Could vitamin D be responsible for this boost in fertility rates?

Of all the nutrients, vitamin D is a curious one. We can get a little from food (greens, mushrooms, fish fat, cod liver oil) as vitamin D2, but mostly we soak it up through our skin as vitamin D3. It's a 'fat soluble' vitamin, so we can store some. Cholesterol carries the vitamin molecule through our liver and kidneys so each can play their part in converting vitamin D from UV radiation to become a powerfully active vitamin that is a major player in building bones. Researchers have learnt it isn’t just our bones that utilise vitamin D; cells on the ovaries, on the placenta and endometrium (lining of the uterus) also present receptors seeking vitamin D, indicating they need this vitamin to function properly.

Curiously, the research done so far around vitamin D and fertility is quite, well, “messy” (to use an unscientific term). There are plenty of studies, but each have utilised different supplement quantities and with sometimes with not enough subjects to reach statistically sound conclusions. Review studies (where all the studies are assessed together) invariably comment that they can’t be sure, for sure, whether vitamin D affects fertility, because the science isn’t strong enough. But at the same time they point to those observations of women’s fertility in the far northern latitudes.

So if you want to know, definitely, that vitamin D boosts fertility, you’ll have to wait while the science develops further. But in the meantime, if your desire is to conceive a baby focus on conceiving consider how much sunlight you are exposed to, whether your workplace has windows, whether you get outside to exercise, and whether your vitamin D levels are sufficient for pregnancy.

If you enjoyed this article you might also enjoy 'The Vitamin You Can Absorb Through Your Skin'

Like to look further? Consider these studies

Azadi-Yazdi, M., Nadjarzadeh, A., Khosravi-Boroujeni, H., & Salehi-Abargouei, A. (2017). The Effect of Vitamin D Supplementation on the Androgenic Profile in Patients with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Clinical Trials. Hormone and metabolic research= Hormon-und Stoffwechselforschung= Hormones et metabolisme, 49(3), 174.

Fang, F., Ni, K., Cai, Y., Shang, J., Zhang, X., & Xiong, C. (2017). Effect of vitamin D supplementation on polycystic ovary syndrome: A systematic review and meta-analysis of randomized controlled trials. Complementary Therapies in Clinical Practice, 26, 53-60.

He, C., Lin, Z., Robb, S. W., & Ezeamama, A. E. (2015). Serum Vitamin D Levels and Polycystic Ovary syndrome: A Systematic Review and Meta-Analysis. Nutrients, 7(6), 4555-4577. doi:10.3390/nu7064555

Irani, M., & Merhi, Z. (2014). Role of vitamin D in ovarian physiology and its implication in reproduction: a systematic review. Fertility and Sterility, 102(2), 460-468.e463. doi:https://doi.org/10.1016/j.fertnstert.2014.04.046

Muscogiuri, G., Altieri, B., de Angelis, C., Palomba, S., Pivonello, R., Colao, A., & Orio, F. (2017). Shedding new light on female fertility: The role of vitamin D. Reviews in Endocrine and Metabolic Disorders, 1-11. doi:10.1007/s11154-017-9407-2

Pergialiotis, V., Karampetsou, N., Panagopoulos, P., Trakakis, E., & Papantoniou, N. (2017). The effect of Vitamin D supplementation on hormonal and glycaemic profile of patients with PCOS: A meta‐analysis of randomised trials. International Journal of Clinical Practice.

Reis, G. V. O. P. D., Gontijo, N. A., Rodrigues, K. F., Alves, M. T., Ferreira, C. N., & Gomes, K. B. (2017). Vitamin D receptor polymorphisms and the polycystic ovary syndrome: A systematic review. Journal of Obstetrics and Gynaecology Research, 43(3), 436-446. doi:10.1111/jog.13250

Shahrokhi, S. Z., Ghaffari, F., & Kazerouni, F. (2016). Role of vitamin D in female Reproduction. Clinica Chimica Acta, 455, 33-38.

Skowrońska, P., Pastuszek, E., Kuczyński, W., Jaszczoł, M., Kuć, P., Jakiel, G., . . . Łukaszuk, K. (2016). The role of vitamin D in reproductive dysfunction in women–a systematic review. Ann Agric Environ Med, 23(4), 671-676.

Voulgaris, N., Papanastasiou, L., Piaditis, G., Angelousi, A., Kaltsas, G., Mastorakos, G., & Kassi, E. (2017). Vitamin D and aspects of female fertility. Hormones, 16(1), 5-21. doi:10.14310/horm.2002.1715

Xue, Y., Xu, P., Xue, K., Duan, X., Cao, J., Luan, T., . . . Gu, L. (2017). Effect of vitamin D on biochemical parameters in polycystic ovary syndrome women: a meta-analysis. Archives of Gynecology and Obstetrics, 295(2), 487-496. doi:10.1007/s00404-016-4247-y

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