The link between Vitamin D and fertility

Caucasian women love showing off a sun-kissed tan, so much so they would dedicate a good portion of their holidays to sunbathing. We Asian women, however, are the exact opposite, preferring to keep out of the sun, sometimes taking considerable pains to do so. This aversion to the sun is largely due to the desire to maintain a fair complexion, but is driven in part by concerns over harmful UV rays. This penchant for shunning the sun, however, has had an undesirable side effect on Asian women, as we are known to have lower levels of Vitamin D despite living in tropical climates.

Few people realise that vitamin D plays a significant role, not only in their general health, but their fertility as well. It has been shown that people living in countries with strong seasonal contrasts have always had fewer pregnancies during winter and more in summer, resulting in a baby boom around spring. Scientists have discovered that this ebb and flow has to do with exposure to the sun.

Over the years, this link between Vitamin D and fertility has been extensively investigated, but it has been further detailed in a systemic review published in 2012 by the European Journal of Endocrinology. The review, by Elisabeth Lerchbaum and Barbara Obermayer-Pietsch from the Medical University of Graz, Austria, assessed studies that evaluated the relationship between vitamin D and fertility in women and men, as well as in animals.

Here’s what the review, entitled ‘Vitamin D and fertility: a systematic review,’ found:

1. Vitamin D receptors (VDR) and vitamin D metabolising enzymes are present in the reproductive tissues of both men and women.
2. Laboratory mice deprived of VDR tend to suffer significant gonad (sex gland) insufficiency, decreased sperm count and motility, and abnormalities in the microscopic structure of tissues in the testis, ovary and uterus.
3. Vitamin D is involved in female reproduction including IVF outcome (clinical pregnancy rates) and polycystic ovary syndrome (PCOS).
4. In PCOS women, vitamin D supplementation might improve menstrual frequency and metabolic disturbances.
5. Vitamin D might influence steroidogenesis of sex hormones (estradiol and progesterone) in healthy women.
6. In men, vitamin D is positively associated with semen quality and androgen status.
7. Vitamin D treatment might increase testosterone levels.

While the results are encouraging, the researchers emphasise that vitamin D supplementation alone can’t improve fertility issues. However, what is certain is that it is a safe and inexpensive treatment that can be a boon to conception. So if you’re trying to conceive, don’t shy away from the sun! Instead, aim to get about 15 minutes of sun each day and take care not to overexpose yourself to UV rays.

In my next post, I’ll be discussing another topic related to fertility and nutrition – the findings of the Dutch Famine Birth Cohort Study. Stay tuned!