Should you take vitamin D supplements this winter?


Since vitamin D production is triggered by a chemical reaction that occurs when our skin is exposed to the sun, most Canadians produce very little or none at all throughout the winter. Can we make up for this by eating foods high in vitamin D? Do we need to take a supplement?

According to Health Canada, adults under the age of 70 need 600 international units (IUs) of vitamin D per day, while those 70 and over need 800 IUs per day.

It’s difficult to meet our vitamin D requirements with dietary sources alone, since very few foods are high in that vitamin. Fatty fish (e.g. salmon, tuna and mackerel) are the foods highest in vitamin D. Next in line are milk, yogurt, some vegetable juices, and orange juice enriched with vitamin D. There is also a little bit in egg yolk and margarine. There is no vitamin D in fruits, vegetables and grains.

In order to make up for this deficiency, Health Canada recommends that all Canadian adults take a vitamin D supplement.

Should we take it only in the winter, or all year? Health Canada recommends taking it all year, for two reasons:

  • In the summer, we need to apply sunscreen (or wear protective clothing) to protect our skin from the harmful effects of the sun, and this prevents our skin from producing the vitamin. Health Canada prefers to make skin cancer prevention the priority, so we should take vitamin D in the summer as well.
  • The skin’s ability to produce vitamin D may be affected by the person’s age, skin type and health.
  • Which supplement should you take? Some contain D2, others have D3. Vitamin D3 (cholecalciferol) is the form most easily absorbed by the body. It comes in various concentrations. To choose the one best suited to your needs, don’t hesitate to consult your pharmacist.