By Perry Holman, Executive Director, Vitamin D Society

Canadians’ vitamin D levels drop substantially in winter due to the lack of UVB in the sun at our northern latitude at this time of year. For November Vitamin D Awareness month, the Vitamin D Society has released a new short video to help people develop a vitamin D winter action plan.

First, let’s understand why a great number of Canadians are vitamin D deficient. Until about 100 years ago, people spent a large amount of their time outdoors. Now most of us work indoors and increasingly spend our leisure time inside, drawn to the Internet, TV, video games and other passive forms of recreation. When we are outdoors, many of us follow health warnings to protect ourselves from UV exposure with sunscreen, clothing and shade.

The result is that Canadians’ vitamin D levels have fallen by 13% in just six years. Approximately 14 million Canadians — 38% of the population — do not meet Health Canada guidelines for vitamin D levels of 50 nmol/L. This puts them at a higher risk for serious diseases such as osteoporosis, diabetes, multiple sclerosis, cancer and cardiovascular disease.

But it gets worse. The vitamin D level recommended by Health Canada is only half the level recommended by a large number of vitamin D experts. Forty eight scientists, doctors and researchers have recommended that everyone reach a 25(OH)D blood level of between 100-150 nmol/L. And nearly all of us, 93% of us in fact, are below these optimal vitamin D levels.

So what can you do to maintain or increase your vitamin D levels in the winter? An adult will need an intake of approximately 4,000 IU/day to reach and sustain optimal levels. Natural sun exposure is best, but at our latitude in Canada, in winter, the UVB rays that make vitamin D in your skin are absorbed in the atmosphere due to the low angle of the sun.

One effective option is to replace outdoor UVB exposure with indoor UVB exposure. A sunbed session can make up to 10,000 IU of vitamin D in your skin. To minimize any potential risk, please follow the instructions of a trained sunbed operator. Skin type 1 (always burn, never tan) people are at a higher risk and should not use a sunbed or expose bare skin to sun outdoors.

The second alternative is to take a daily vitamin D3 supplement of up to 4,000 IU/d for adults. For most individuals, this will raise their vitamin D levels to optimal levels. However, for some people, those with malabsorption issues such as Crohn’s disease or kidney disease, they cannot absorb vitamin D through their digestive system. UVB exposure would be their only option.

It should be noted that not all the benefits of UV exposure are found in vitamin D supplements. For example, UV exposure produces photoproducts such as serotonin and endorphins for mood improvement, and reduces nitric oxide in your skin which can lower blood pressure. In addition, new research has found that vitamin D3 supplements may increase your cholesterol levels, while UV exposure reduces it.

It’s important for all Canadian residents to decide what vitamin D source is right for them individually.

Food has very low amounts of vitamin D, but can contribute a small amount. The best sources are oily wild fish (like salmon), fortified milk or juice products, eggs and mushrooms. An adult will need a vitamin D intake of up to 4,000 IU/day. Wild salmon have 500 IU/serving. So you would need 8 servings of salmon per day or 40 glasses of milk to meet your daily intake requirements. This is why food is not recommended as a primary option.

To check and see if you are getting enough vitamin D, you can request the 25(OH)D test through your physician (a fee may apply) , or arrange a test online. Make sure your score is in the range between 100-150 nmol/L.

Please look after your vitamin D this winter!