Do I need Vitamin D - a Canadian Perspective
A hot topic for nutrition these days is whether or not you actually need to be taking vitamins, and probably the biggest contender for this question is vitamin D, or more specifically vitamin D3. The short answer is - probably. Of course this doesn't take into account where you live, what time of year it is, or how much time you spend outside. So lets go over what vitamin D is, why we need it, and how to get it.
Vitamin D is a fat-soluble vitamin, and is necessary for a number of reasons, including calcium absorption, cell growth, and even immune functions. There are two types of vitamin D that our bodies use - D3 and D2. Note that D3 primarily comes from animal sources, while D2 comes from yeast or mushrooms that have been exposed to UV rays, and is a better option for most vegans. There are also common foods that are now supplemented with vitamin D, such as cows milk, and many cereals on the market in North America. Of course the other way most people know of getting vitamin D is through sun exposure. The lower layers of the skin can actually produce vitamin D3 because of a chemical reaction caused by UVB radiation.
As far as why we need to supplement, in Canada a primary component is our winter lack of sunshine. While people may feel that they get enough sunlight year round, a factor that is often overlooked is that being indoors drastically reduces the ability for your body to create vitamin D itself as most windows block the necessary UVB rays needed to do so. At optimal levels of UBV exposure, 5-30 minutes twice a week can actually produce enough vitamin D for our bodies requirements. Another factor with modern beliefs about sun exposure is that SPF products severely hinder vitamin D generation as well. SPF 8 is able to block vitamin D creation by the skin by 95%, and SPF 15 increases that to 98%. While using SPF is highly recommended to help prevent skin cancer, unfortunately this reduces the bodies ability to produce enough vitamin D itself, and increases the need for supplementation. Another factor in Canada is, as mentioned above, the lack of sunshine hours in the day combined with the angle of the sun at our latitudes. While that 5-30 minutes twice a week is great potentially at the equator, combining a much greater time frame needed with the lack of sunlight hours, weather factors such as clouds and storms that can block UVB exposure further, and the temperatures having people cover with more clothes and spend less time outdoors, we are a country that is prone to vitamin D deficiencies due to our environment.
The other aspect to be aware of when determining if you may have a deficiency is knowing what vitamin D deficiency symptoms look like. Even at a low level of deficiency, you can have issues with getting sick often or have trouble fighting off infections (vitamin D plays a role in the immune system). Deficiency can also cause you to feel more fatigued and worn down, and it doesn't even take much of a deficiency to feel this effect. It is not uncommon for people in winter to feel more fatigued when they spend days indoors, and feel much more energetic if they spend a day outside, even if they are mostly well bundled up. Another sign of deficiency is bone pain. Because vitamin D helps with calcium absorption, lacking in vitamin D can play a vital role in your bones, and associated pain when not enough calcium is being absorbed by the body. This is actually one reason most dairy is fortified with vitamin D, as it works hand in hand with calcium and increases calcium absorption when they are consumed together. Lastly, wounds not healing well can be a sign of deficiency, as vitamin D increases the production of skin-forming compounds as part of the healing process. While you may have all, some or none of these symptoms, it doesn't mean one way or the other if you are deficient or not. Many of these symptoms can have other, completely unrelated causes as well, so while any of these can point to a possible deficiency, diagnosis can't be done from symptoms alone. It is also possible to be deficient and not show any of these symptoms. As with most vitamin deficiencies, especially low level ones, some symptoms may be more or less likely depending on so many other factors that there is no clear-cut way to know if you are deficient just by their presence.
So what does that mean for the question "Do I need Vitamin D?" - the general answer for Canadians is - if it is fall, winter or early spring, probably. Any other time of year, if you are mostly indoors and/or use a lot of SPF sunscreen, then probably. The more focussed answer is - talk to your doctor first and foremost if you are concerned and get your levels tested. If you know you are in the risk group for being deficient (indoors, away from sunshine, well covered with SPF, work night shifts so rarely out in the sun... pretty much anything that results in your barely getting any direct contact with sunshine on your exposed skin... it is probably a good idea to supplement. But do keep in mind that excess vitamin D can cause calcium buildups in your blood and urine, so self-prescribing doses is not recommended even if you have confirmation you are deficient without medical/nutritional supervision. As everyone's body is different, and things like skin tone, body fat, and some gastrointestinal issues can change your absorption rates, it is always recommended that you speak with a doctor or nutritionist to determine your optimal intake in the form of a supplement. If you are concerned you may be and want to start by improving your diet sources of vitamin D, increase your intake of tuna, shitake mushrooms, or fortified products such as dairy, cereal or juices). Nutritional intake should not take place of possible medical analysis if you are showing symptoms of possible deficiency, but can provide a helpful boost at times you are concerned prior to starting supplements, and based on medical recommendations could be a possible alternative to supplements for low level deficiencies.