Vitamin D in Winter: A Free Guide for Canadians Over 50

Shorter days mean less sunshine and less vitamin D. This free guide covers how much you need after 50, where to find it, and what to ask your doctor before winter sets in.

1. Why winter makes it harder

Your skin makes vitamin D from sunlight. In a Canadian winter the sun is low, the days are short, and most of us stay indoors or covered up. Statistics Canada reports that about 13% of Canadians have vitamin D levels below the deficiency cut-off from November to March, compared with 5% from April to October. Skin also becomes less efficient at making vitamin D as we age.

2. How much you need

Age	Recommended daily amount (Health Canada)
51 to 70	600 IU (15 mcg)
Over 70	800 IU (20 mcg)
Safe upper limit, adults	4,000 IU a day from all sources

Health Canada also advises adults over 50 to take a daily vitamin D supplement of 400 IU, along with foods that contain it. More is not better: regularly going above 4,000 IU a day can cause harm, including high blood calcium.

3. Foods that help

• Fatty fish: salmon, trout, sardines, mackerel
• Cow's milk and fortified plant beverages (soy, almond, oat)
• Fortified margarine
• Egg yolks

Adults who eat fish weekly, drink milk daily or take a supplement are much less likely to have low vitamin D, according to Statistics Canada.

4. What the research says

Vitamin D is essential for absorbing calcium and keeping bones and muscles strong. But large studies such as the VITAL trial found that extra vitamin D did not reduce fractures in healthy adults over 50 who already had enough. The goal is to meet your daily needs, not to take very high doses on your own.

5. Your doctor checklist

Print this or save it to your phone for your next appointment:

• ☐ Should I take a vitamin D supplement, and how much?
• ☐ Do I need a vitamin D blood test? (In many provinces it is only covered with a medical reason.)
• ☐ Do any of my medications, such as steroids or water pills, affect vitamin D or calcium?
• ☐ Should I take calcium too, or do I get enough from food?
• ☐ Would a bone density test make sense for me?

6. Winter habits that help

• Get outside in daylight when you can; it helps your mood and keeps you active, even when it does little for vitamin D.
• Plan two or three fish meals a week.
• Check labels on milk and plant beverages for added vitamin D.
• Choose a supplement that fits Health Canada's advice and your doctor's recommendation.

Sources: Health Canada, Dietary Reference Intakes for vitamin D; Statistics Canada, Canadian Health Measures Survey 2016 to 2019; U.S. National Institutes of Health, Office of Dietary Supplements; LeBoff et al., VITAL trial, New England Journal of Medicine, 2022.

This guide is for general information only and is not medical advice. Talk with your doctor or pharmacist before starting any supplement.