Vitamin D and Fertility

When I think of Vitamin D the first thing that comes to mind is sunshine!

Why? Because we rely on the UVB rays of the sun in order to produce Vitamin D in our skin!

Taking a Vitamin D supplement is extremely important in Canada since we do not get enough sunlight. Especially in the winter months when we are all bundled up with no skin exposed and the sun isn’t as strong. Other factors that may influence our ability to make Vitamin D include our complexion, sunscreen use, cloudy days, time of day and latitude. Generally, those with lighter skin tones are able to synthesize Vitamin D better than those with darker skin tones.

So how do you know if you are deficient in Vitamin D?

Well, your doctor can order a simple blood test to determine your Vitamin D levels. The correct test is 25 hydroxyvitamin D as it is the best marker for Vitamin D status. According to Life Labs in Canada below are the various reference ranges.

<25 nmol/L25-74 nmol/L75 nmol/L>250 nmol/L


Lower levels of Vitamin D have been shown in various autoimmune diseases such as multiple sclerosis, type 1 diabetes, lupus, inflammatory bowel disease and autoimmune thyroid disease. Ultimately, it is a good idea to get tested and depending on your blood level a specific amount of Vitamin D will be prescribed to you – but it can be anywhere between 400IU to 10,000IU!


What are the true benefits of taking a Vitamin D supplement?

Vitamin D is very unique as its’ chemical structure is very similar to hormones. In fact, we know that there are Vitamin D receptors on ovaries, endometrium, and the pituitary gland (the gland that produces hormones). So, there must be some benefits of Vitamin D on fertility. Below are some of the benefits of having optimal levels of Vitamin D in relation to reproductive health:

  • Helps to ensure optimal quantity and quality of sperm
  • Improves insulin resistance in PCOS patients
  • Stimulates Anti-Mullerian hormone (AMH) which is related to ovarian reserve
  • Has an anti-inflammatory effect
  • Can increase the success rate of IVF procedure
  • May help with implantation of the embryo
  • Improves mood

Lower levels have been seen in patients with PCOS and fibroids – both of which are related to infertility. Lower levels have been shown to increase infertility but also pregnancy complications such as preeclampsia (high blood pressure in pregnancy) and preterm birth.


How do you know which supplement is best?

Well, there are two different forms of Vitamin D known as D2 and D3. Vitamin D3 is the form that is synthesized through our skin which eventually makes it way to the liver to become metabolized into its active form known as 25-hydroxycalciferol. Vitamin D2 is a synthetic form – so make sure when buying a supplement that you purchase Vitamin D3. Also, the liquid form is always best because it is better absorbed.

How much Vitamin D should you get to optimize your fertility success??

Overall, taking a Vitamin D supplement to maintain your levels is quite important while trying to conceive. Vitamin D works on so many different levels and is important to our reproductive health. When I first got my Vitamin D levels tested years ago, my level was 7 nmol/L (where the normal should be between 75-250 nmol/L) – can you believe that?! Since then I have ensured that I regularly take Vitamin D ☺

Each person is different, depending on what their serum levels of Vitamin D are, this will help to determine the exact dose you should be receiving. I always recommend getting a blood test and then determining with your doctor what the appropriate dosage is for you. However, doses of up to 4,000IU is common for optimizing fertility.

As always, speak to your Doctor before changing any vitamins or medications. All the information provided above is to be used as a reference and does not replace medical advice.


Check out more fertility related articles at


Dabrowski, Filip, Barbara Grzechocinska, and Miroslaw Wielgos. “The Role Of Vitamin D In Reproductive Health—A Trojan Horse Or The Golden Fleece?”. Nutrients 7.6 (2015): 4139-4153. Web. 19 Jan. 2017.

“Lifelabs – Test Information Directory – Homepage”. N.p., 2017. Web. 19 Jan. 2017.

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