Vitamin D in Canada
Canada spans latitudes 42° N (Windsor) to 82° N (northernmost Nunavut) — every Canadian outside the far south experiences meaningful winter vitamin D shortage. Health Canada has recognised this since the 1970s with mandatory milk fortification, and current guidance encourages supplementation for adults over 50 in particular.
Health Canada RDAs
- Ages 1–70: 600 IU/day (15 µg).
- Age 70+: 800 IU/day (20 µg).
- Pregnancy / lactation: 600 IU/day.
- Health Canada supplementation recommendation for adults over 50: 400 IU/day cholecalciferol year-round in addition to dietary sources.
- Tolerable upper limit: 4,000 IU/day for adults.
Milk fortification
Canadian regulations require vitamin D fortification of all fluid milk and margarine at defined levels (35–45 IU per 100 mL milk; 5.3 µg per 100 g margarine). This has substantially reduced rickets since the 1970s but hasn't eliminated adult winter deficiency, given the modest doses involved.
Deficiency prevalence
Canadian Health Measures Survey data: ~30% of adults have 25(OH)D below the Endocrine Society sufficient threshold in winter. Rates rise to 60–80% in Indigenous northern communities and in South Asian and Black immigrant populations. Nunavut and NWT communities have particular challenges — polar night in the far north, and traditional diet shifts have reduced marine-oil intake.
When Canadians make vitamin D
Roughly April through September for southern cities (Vancouver, Toronto, Montreal, Halifax); May through August for northern cities (Edmonton, Winnipeg, Saskatoon). Meaningful synthesis only around midday. Winter sun does not produce vitamin D anywhere in Canada.
Buying supplements in Canada
- OTC at Shoppers Drug Mart, Rexall, London Drugs, supermarkets, and health-food stores.
- Standard 1,000 IU cholecalciferol tablets $5–10 for a year's supply.
- 1,000 IU is a widely available size; often described as "the Canadian dose."
- Higher-strength 2,000–5,000 IU widely available.
- Prescription-only 50,000 IU capsules for correction of documented deficiency.
Testing 25(OH)D in Canada
Provincial healthcare coverage of 25(OH)D testing varies. Ontario and some other provinces restricted publicly-funded testing after 2010 (billing rules require specific indications). Private tests cost $30–80 at LifeLabs, Dynacare, or private lab groups. Home finger-prick tests (Vitamin D Council, Better You) are also available.