Nutrients
Vitamin D (25-hydroxyvitamin D)
25(OH)D
Included in every MyHealthspan membership: Focus, Baseline, and Complete.
Compare membershipsYour vitamin D from sun, food, and supplements.
This test measures 25-hydroxyvitamin D, the main circulating form of vitamin D. It reflects what you've made from sunlight and taken in from food and supplements over recent weeks. Vitamin D helps your body absorb calcium to keep bones strong.
Canadian winters make vitamin D harder to get.
From October to March, reduced daylight makes it hard for people in Canada to make much vitamin D in their skin. Few foods contain it naturally. Health Canada advises eating foods with vitamin D, including fortified foods, every day or taking a daily supplement, and it recommends a daily supplement for everyone over 50.
Skin pigmentation, body weight, age, sunscreen, time outdoors, and absorption problems all affect your level, so two people with similar habits can have different results. Results can also vary somewhat between labs.
Season, skin, and supplements all show up in this result.
Questions
Is there one ideal vitamin D level?
Experts don't fully agree. Labs and guidelines use different cut-offs, and the Endocrine Society's 2024 guideline found that trials haven't established a level that delivers specific health benefits. Your result is best read with your bone health, diet, sun exposure, and other results.
Can vitamin D be too high?
Yes. Very high levels usually come from taking too much in supplements over time, and too much vitamin D can raise calcium in your blood. If your result is high, your clinician will likely review your supplements and your calcium level.