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  • Writer's pictureLiza Klassen

Vitamin D: The sunshine vitamin

This vitamin has received a lot of media over the past year - and for good reason(s)!

It's implicated in the proper functioning of almost every body system;

  • Regulates insulin levels (hello PCOS patients)

  • Impacts and improves mood (including mood disorders like depression & anxiety)

  • Gynaecological conditions including; Fertility optimization and miscarriage prevention

  • Maintains bone and teeth health (which becomes paramount as we age/for post-menopausal women)

  • Immune support and immune cell activation (not just colds/flus, immune support is also important for auto-immune conditions like Hashimoto's, Celiac, Lupus)

  • Supports respiratory and cardiovascular health

It's estimated that between 70-97% of Canadian's demonstrate vitamin D insufficiency. Insufficient vitamin D is defined as levels less than 80nmol/L in the blood. And sufficient is NOT optimal, to put this in perspective I want to see vitamin D levels greater than 100nmol/L…

So What is Vitamin D?

Vitamin D is an essential, fat soluble vitamin that our bodies can synthesize from sunlight! There's this amazing reaction that occurs at the skin when the sun’s ultraviolet-B (UVB) rays interact with an inactive precursor to vitamin D. This sets off a cascade of activation that requires both the liver and finally the kidney to produce the active form (the form our body can use) of vitamin D called 25-hydroxyvitamin D3.

Why are so many people deficient?

There are just a few reasons…

  • The conversion to active vitamin D isn't a simple process (as you can see above) and as we age we get worse at this process

  • Unlike most essential vitamins we are unable get adequate vitamin D from dietary intake

  • Living in northern latitudes (like Canada) means that during the winter months we actually can't synthesize vitamin D from the sun because the UVB rays just aren't strong enough

  • Vitamin D is fat soluble, meaning it matters HOW you take it

You should care about this if…

  • You have PCOS.

  • Rates of vitamin D insufficiency are greater in women with PCOS than the general population. When we supplement vitamin D for women with PCOS it lowers abnormally elevated AMH, improves insulin sensitivity (especially when combined with metformin) and improves ovulation and regularity of menstrual cycles

  • You have PMS.

  • Women who experience PMS have lower vitamin D levels in the luteal phase of their cycle (the time between ovulation and your period) vs. the general population. More importantly, when you give women with PMS high levels of vitamin D it reduces their symptoms!

  • You're trying to GET pregnant.

  • If you're considering or currently undergoing IVF therapies, ensuring your vitamin D levels are adequate is essential. Research shows that adequate vitamin D improves success rates and live birth rates for women undergoing IVF.

  • You're trying to STAY pregnant.

  • Vitamin D is thought to play a critical role early in pregnancy. This makes sense as there are both receptors for vitamin D and high concentrations of the vitamin in the uterus. Research suggests vitamin D helps with proper implantation and supports our immune system's response to the embryo ultimately favouring maintenance of the pregnancy.

Should you get your vitamin D tested? YES. That is all (for now).

Should you take vitamin D? Public health just increased their recommendation of daily vitamin D intake from 1000IU/day to 2500IU/day. Is this enough for you? We don’t know until we see your blood work.

Moral of the Story; vitamin D is essential, it's implicated in almost every system in the body including gynecological concerns like; PMS, PCOS, pregnancy and miscarriage prevention and you're probably not in optimal range (even if you're supplementing).


  1. Schwalfenberg GK, Genuis SJ, Hiltz MN. Addressing vitamin D deficiency in Canada: a public health innovation whose time has come. Public Health. 2010;124(6):350-359. doi:10.1016/j.puhe.2010.03.003

  2. Lin MW, Wu MH. The role of vitamin D in polycystic ovary syndrome. Indian J Med Res. 2015;142(3):238-240. doi:10.4103/0971-5916.166527

  3. Heidari H, Amani R, Feizi A, Askari G, Kohan S, Tavasoli P. Vitamin D Supplementation for Premenstrual Syndrome-Related inflammation and antioxidant markers in students with vitamin D deficient: a randomized clinical trial. Scientific Reports. 2019;9(1):14939. doi:10.1038/s41598-019-51498-x

  4. Grzechocinska B, Dabrowski FA, Cyganek A, Wielgos M. The role of vitamin D in impaired fertility treatment. Neuro Endocrinol Lett. 2013;34(8):756-762.

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