Winter is coming.

For a lot of us in North America (especially Canada) that means kissing exposure to sunshine goodbye for several months. Without that sun exposure, many of us are put at risk for not getting enough of the “sunshine vitamin” – vitamin D.


“Wait, wait – I thought vitamins come from food?”

You’re mostly right. However, our skin makes vitamin D when exposed to the sun. Neat, right? When our skin is exposed to the sun’s ultraviolet (UV) rays, a chemical reaction occurs and our bodies’ begin the process of converting a precursor existing in the skin into a form of vitamin D that our bodies can use. It has been said that 5-30 minutes of exposure to the sun between 10:00 am and 3:00 pm 3 times per week should be enough for our bodies to synthesize vitamin D. I don’t know about you, but in the Canadian wintertime that’s a challenge.


“Okay, so what’s so important about Vitamin D?”

 Lot’s of things! Most of us know vitamin D for it’s important role in maintaining healthy bones and teeth. The presence of vitamin D aids in calcium absorption, and together the calcium and vitamin D duo helps to keep our bones and teeth strong and healthy. But vitamin D doesn’t stop there. It has also been researched for its role in:


  • Immune Function: Vitamin D is known to act as a regulator of the immune system as it suppresses the over-expression of pro-inflammatory compounds in the body – meaning it may be helpful in preventing chronic inflammation.


  • Diabetes and Heart Disease: There is much emerging research that vitamin D may play a role in the prevention and treatment of diabetes and heart disease. Read about some of that here and here.


  • Colon, Prostate, and Breast Cancer: There is currently ongoing and conflicting research in these areas, and more evidence is required, but some lower-quality studies have suggested that high vitamin D levels are associated with a reduced cancer risk, here and here.


  • Multiple Sclerosis (MS): Some data (here and here) suggests that individuals with MS may have lower serum vitamin D levels than the general population, and supplementation may have beneficial effects for MS patients.


“Alright, alright. So where else can I get it?”

You can get vitamin D three ways. Through the sun, diet, and supplements. Now because it’s wintertime, we’re going to focus on ways to get vitamin D without Mr. Sun (do you guys remember that song?)


  • From Food: Vitamin D can be found in a small handful of foods – either naturally occurring or fortified. Naturally occurring vitamin D is found in egg yolks and fatty fish (like salmon, tuna, mackerel, and sardines). On the other hand, some foods are required by the Canadian government to be fortified with vitamin D. This includes cow’s milk, infant formula, and margarine. Yogurt and cheese made with vitamin D-fortified milk are also food sources. Additionally, goat’s milk, plant-based milk alternatives (like soy milk) and some orange juices may be fortified with vitamin D as well. Be sure to read the Nutrition Facts table and ingredients list on these products to make sure!


  • From Supplements: Since there are only so many foods that contain vitamin D, some of us may struggle to get enough through diet alone (especially in these winter months!). Therefore, adding a vitamin D supplement to your routine may be necessary, especially if you know you do not consume enough vitamin D rich foods. Vitamin D supplements can be found in tablet, gummy, and drop forms.


“So how much vitamin D do we need?”

 Great question. You can find your needs based on your age here. Keep in mind that these are general recommendations. If you’re concerned that you’re not getting enough vitamin D (or any vitamin or mineral) I always recommend speaking to your healthcare provider or seeking a Registered Dietitian for help with this.

Vitamin D is a fat-soluble vitamin. Meaning that it is absorbed in our GI tracts alongside fat that we consume. Therefore, I recommend taking your vitamin D supplement with a fat-containing meal or snack to ensure better absorption. As a fat-soluble vitamin, this means that it is not as easy for our bodies to excrete or get rid of it if we take in too much. And too much vitamin D is also not good for us. So if you are supplementing vitamin D, please do not take higher-than-recommended doses without first consulting your doctor.


“What’s the bottom line – do I need a supplement?”

In conclusion, I do believe that adequate vitamin D levels can be achieved without supplementation through adequate sun exposure and a well-planned diet. However, Canadian winters tend to be brutally cold and dreary, meaning that our time spent outdoors and exposed to sunlight is minimal. Even when we do spend time in the sunshine, wearing protection in the form of sunscreen and clothing inhibits vitamin D production. This leaves us to rely on our diets for vitamin D. As discussed, there are limited foods that contain vitamin D, so if you are not consuming adequate food-sources of the vitamin (listed above), taking a supplement is a good idea.

I would also recommend a vitamin D supplement if you are:

  • Age 50 or older. Health Canada recommends that men and women 50+ take 400IU of vitamin D each day.
  • Following a vegan diet.
  • An infant who is fed only breastmilk OR fed breastmilk and formula. 400 IU of vitamin D daily until two years of age.

You may need a vitamin D supplement if you have Crohn’s disease, celiac disease, chronic kidney disease, parathyroid disease, and some forms of liver disease. Please speak to your healthcare provider about your requirements. 

I always recommend speaking with a dietitian about your dietary habits to determine the appropriateness of a supplement. Interested in chatting with me about this? Check out my nutrition counselling services here.