The one supplement every parent should actually be taking

I am a physician. I am generally sceptical of supplements. Most of the supplement industry is predicated on people spending money on things with marginal or no evidence. But there is one exception for Canadian parents, and the evidence is overwhelming.

Vitamin D

Approximately 70% of Canadians are vitamin D deficient or insufficient, according to Statistics Canada. In parents specifically — who typically spend more time indoors and less time outdoors than non-parents — the number is likely higher.

This is not a minor issue. Vitamin D is not a vitamin in the traditional sense. It is a hormone precursor that affects over 200 gene expressions in the human body.

What vitamin D deficiency actually causes

• ✓Persistent fatigue that does not resolve with sleep
• ✓Reduced immune function (associated with higher frequency of respiratory illness)
• ✓Low mood and seasonal depressive symptoms
• ✓Reduced testosterone in men and estrogen regulation in women
• ✓Impaired muscle recovery and increased injury risk
• ✓Poor calcium absorption, independent of dietary calcium intake

For parents in Ontario, Quebec, or the Prairie provinces, UV-B radiation is insufficient to produce meaningful vitamin D from October through April regardless of how much time you spend outside.

The right dose

Health Canada recommends 600 IU for adults. Most vitamin D researchers consider this insufficient for people starting from a deficient baseline. A more practical target for deficient adults is 2,000–4,000 IU daily, taken with a fat-containing meal (vitamin D is fat-soluble).

The only way to know your level is a 25-OH vitamin D blood test — ask your family physician. Optimal range is generally considered 75–150 nmol/L.

D3, not D2

Vitamin D3 (cholecalciferol) is what your skin produces from sunlight and is significantly more effective at raising blood levels than D2 (ergocalciferol). Always choose D3.

Why not just a multivitamin?

Most multivitamins contain 400–1,000 IU of D2. This is insufficient for a deficient adult and in the less effective form. A dedicated D3 supplement is more effective and typically less expensive per dose.

If there is one thing you start taking this month, this is it.