Vitamin D deficiency: Who is at risk and how to keep levels up this winter

With lower sun exposure in the winter months, there is an increased risk of vitamin D levels dropping, experts warn. Here's what you should know.

As winter weather settles in Canada, a “silent” health issue could be impacting many in the country.

With people spending more time indoors and getting less sun as days get shorter, there is an increased risk of your vitamin D levels dropping, experts warn.

Vitamin D is well-known for its role in keeping bones, teeth and muscles healthy by promoting the body’s absorption of calcium. It is also critical for the proper functioning of our immune system, which protects the body from viruses and bacteria.

But vitamin D deficiency is a “widespread” problem not only in Canada but across the world, said Dr. John White, chair of the department of physiology at McGill University.

And weather is a contributing factor, as vitamin D levels obtained through sunshine fluctuate throughout the year, he said.

According to the latest Statistics Canada report from 2015, in the winter, about 40 per cent of Canadians were below the appropriate cut-off of vitamin D levels needed for healthy bones — 50 nmol/L. In the summertime, 25 per cent of the population were below the cut-off.

Anyone under 30nmol/L is considered vitamin D deficient, according to StatCan.

Without a 25-hydroxy vitamin D blood test it’s difficult to know if your levels are insufficient as there are few warning signs or symptoms, said White.