Vitamin D in a Canadian Winter: What to Take and Why
Between October and April, most Canadians cannot make vitamin D from sunlight. Here is the dose most family doctors quietly recommend — and why.
Medically reviewed by Marie Leblanc, RD
Registered Dietitian, Montréal QC
Written by UnityLife Admin
Updated April 2026 · Reviewed March 2026
North of the 42nd parallel — which includes almost all of Canada — the angle of winter sunlight is too oblique to synthesise vitamin D through your skin. That is why vitamin D deficiency is common in Canadian adults, and why a daily supplement is one of the easiest wellness wins in the country.
How much Canadians actually need
Health Canada’s RDA is 600 IU/day for adults, 800 IU/day over age 70. Osteoporosis Canada and most Canadian family doctors recommend 1,000–2,000 IU/day for most adults, particularly from October through April.
The upper limit is 4,000 IU/day — toxicity is rare but real at higher doses.
How to take it
Take it with the meal containing the most fat — vitamin D is fat-soluble. D3 (cholecalciferol) is preferred over D2.
Who should get tested
Ask your family doctor for a serum 25-hydroxyvitamin D test if you rarely go outside, have darker skin, are pregnant, or have osteoporosis.
The bottom line
A 1,000 IU daily vitamin D3 supplement is one of the cheapest, best-evidenced wellness habits a Canadian can build. It costs about eight cents a day.
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The bottom line
A 1,000 IU daily vitamin D3 supplement is one of the cheapest, best-evidenced wellness habits a Canadian can build. It costs about eight cents a day.
Frequently asked questions
It is difficult. Canadian cow’s milk and some plant milks are fortified, but most Canadians still fall short in winter.
Sources & further reading
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