A disturbing new study indicates that Canadians – particularly women – are not getting an adequate amount of vitamin D. Since the best source of vitamin D is summer sunlight, one can guess what might be the reasons for a deficiency—we have a short summer. For the other half of the year, Canadians are bundled up from head to toe and even if there is some skin exposed, winter sunlight barely registers.

One problem in summer is for years people have been warned about the dangerous nature of sunlight in causing skin cancer and thus are doing what they have been told—slathering on sunscreen (which blocks the body’s ability to make vitamin D), covering up or staying out of the sun completely.

How important is vitamin D to health and if sunlight is not our main option what are other sources?

What has come to light in recent years is that a deficiency of vitamin D may be one of the factors in chronic conditions such as osteoporosis, muscle and joint pain, high blood pressure, colon cancer and multiple sclerosis. Vitamin D also helps regulate blood sugar levels and immune system responses, and supports cognitive function especially in older folk.

It is common knowledge that vitamin D helps in the absorption and storage of calcium which, in turn, keeps bones strong. This explains how a shortfall of the vitamin would increase bone deterioration and lead to rickets (in serious cases) identified by thin and misshapen bone, arthritis and multiple sclerosis. Why lack of vitamin D is a risk factor for cancer and hypertension is not entirely understood.

Required by the human body

With recent research showing that vitamin D is more important to optimum health than previously thought, Health Canada concluded requirements had been underestimated and thus recently raised its recommended intakes. Today recommended daily intake for everyone over the age of one is 600 to 1000 international units (IU).

Direct sunlight is by far the best source of vitamin D (what actually happens is that the vitamin forms under the skin in reaction to sunlight) – and it only takes 10 to 15 minutes a day for an adequate amount. Canadians should not be afraid to get that amount of sunlight during summer. However, from October to March the sun doesn’t get high enough in the sky to stimulate production.

Another important source of vitamin D are those foods that have been fortified such as milk and some breakfast cereals (check the label). Other sources are fatty fish (such as salmon, tuna, sardines and lake trout) and eggs. Of these, fatty fish is the best source (400 IU per 6-ounce serving of wild salmon) followed by milk (100 IU per 8-ounce glass). This again poses a problem because fish is not everyone’s favourite food and tends to be expensive, and many adults don’t drink milk.

One thing to remember is that vitamin D is fat-soluble which means excess amounts are stored in the body, ready for use on the days when intake is low. This also means that vitamin D can’t be absorbed without fat; thus diets should provide a certain amount of healthy fat (that is unsaturated or polyunsaturated fat found in plant-based foods and fish).

Because it is a challenge for people living in northern climates to get enough vitamin D from the sun, and it might be difficult to get adequate amounts from food, many nutritionists recommend a supplement, at least in winter. Many older folk grew up with a daily dose of cod liver oil which supplied the “sunshine vitamin” whether they knew it or not. Currently, vitamin D is offered in easy-to-swallow capsules or liquid drops.