By Zeynep Uraz, Naturopathic Doctor

We’re back with part 3 in our preconception series.  Our topic is vitamin D – the sunshine vitamin.  

You may already have heard a lot about vitamin D and the role it plays in reproductive health. This is a particularly important topic because so many Canadians are vitamin D deficient.  In fact, about 40% of Canadians in their reproductive years are deficient in vitamin D.

Our bodies make vitamin D when our skin is exposed to the sun. Given the individual variability in skin tone, time spent outdoors, and body weight, vitamin D levels in the blood can vary *a lot* between individuals. Also, during the winter months in Canada, it is very difficult to synthesize vitamin D from sun exposure. 

Vitamin D plays a significant and important role in reproductive health. One large study that combined several smaller studies (including 2700 women undergoing ART/IVF) showed that those who had healthy vitamin D levels had a significantly higher chance of pregnancy and live birth.  Keep in mind that these are *associations*.  There are no large studies looking at supplementation and its impacts on pregnancy rates and live birth rates.  More on this later.  

If you have PCOS, vitamin D deficiency is especially relevant. In these individuals, lower vitamin D levels are associated with more severe symptoms, and supplementation with vitamin D might help with menstrual cycle regularity and metabolic health.  

Lower serum vitamin D levels are also associated with lower sperm parameters (count, motility and morphology). 

Vitamin D deficiency in pregnancy is associated with a greater chance of negative outcomes (gestational diabetes, preeclampsia and low birth weight). Again, these are associations, but still, it makes sense to optimize blood levels of vitamin D before pregnancy. 

Considering the broad impact of vitamin D on reproductive health, and knowing that vitamin D supplementation is generally safe, cost-effective, and could possibly have a real impact on fertility and on the health of a pregnancy, it is worth considering supplementation.  

While vitamin D is by no means the cure-all to infertility, having adequate/replete levels in the blood before going into a treatment cycle can only help your chances of a successful outcome.  But keep in mind, just like any vitamin or mineral, supplementation is only helpful in those who are deficient. And too much vitamin D can be harmful too.  

Can you get vitamin D from food? 

Yes, there are some specific foods that have moderate amounts of vitamin D in them (fatty fish), and fortified foods (dairy).  Beyond that, it is challenging to get sufficient amounts of vitamin D from food sources, and most people cannot get enough from food sources alone.  

So, should you supplement and how much? 

If you are deficient, yes. Though, there are some individuals in which supplementation can be harmful. So it is always important to check with your care provider (fertility doctor/REI, family doctor or naturopath).  

If you are deficient, how much should you supplement? 

Different factors may impact how much you may need.  Those who have higher body weight will require more vitamin D. And even if you are supplementing with vitamin D, we still recommend getting outside daily, when possible, as there are many other benefits to being outside! 

It is generally considered safe to take in the range of 600-800 IU of vitamin D.  If you have low blood levels of vitamin D, you will need more.  Vitamin D is a fat-soluble vitamin, which means excess levels are not excreted in the urine, but rather are stored in body fat.  That means that getting too much can be harmful.  If you are supplementing with higher doses, it should be for a predetermined period of time.  A knowledgeable care provider will take into account your blood levels and various factors that can impact how much you need and for how long.  If you are planning fertility treatments as soon as clinics reopen, you may want to get your blood levels up faster. 

Vitamin D plays an important role in reproductive health.  You may be among the many Canadians who are deficient. If so, check with your care provider to work on getting your levels up to an ideal value while you prepare for pregnancy.  This small change may make a tangible difference to your fertility, and hopefully, your future pregnancy. 


About the Author

Zeynep Uraz ND
Zeynep is a Licensed Naturopath and an Associate Professor at The Canadian College of Naturopathic Medicine where she teaches Integrative Fertility and leads the fertility care centre at the college’s teaching clinic. She is also a member of both the Canadian Fertility and Andrology Society and the European Society of Human Reproduction and Embryology.