Vitamin D is unusual: your skin can make it from sunlight. That works well in summer, but for much of the year, and for many people, it isn't enough. Low vitamin D is common across North America, especially in Canada and the northern US.
What vitamin D does
- Helps your body absorb calcium and phosphorus, which build and maintain bones and teeth.
- Helps maintain immune function.
- Supports normal muscle function.
Signs your vitamin D may be low
Mild shortfalls often cause no symptoms at all. When levels are low for longer, people may notice:
- tiredness or low energy;
- aching bones, especially in the back or legs;
- muscle weakness or cramps;
- low mood, particularly in winter.
These signs have many possible causes, so a blood test is the only way to know.
Who is most at risk?
- People in northern regions. Above roughly 37 degrees latitude (north of San Francisco, Denver or Richmond, Virginia, and all of Canada), the winter sun is too weak for your skin to make meaningful vitamin D from about November to February.
- Older adults, whose skin makes vitamin D less efficiently.
- People with darker skin, which needs more sun exposure to make the same amount.
- People who spend most of the day indoors or cover most of their skin outdoors.
- People with higher body weight, as vitamin D is stored in fat tissue.
- People with conditions affecting fat absorption, such as Crohn's or celiac disease.
How much vitamin D do you need?
US and Canadian guidelines recommend 600 IU a day for most adults up to age 70 and 800 IU a day over 70, assuming minimal sun. The general upper limit for adults is set at 4,000 IU a day. Higher amounts are sometimes used to correct a shortfall, but should be taken with guidance from a healthcare provider, ideally based on a blood test.
Understanding your blood test
The test measures 25-hydroxyvitamin D. The US National Institutes of Health uses these general guides:
| Level | nmol/L | ng/mL |
|---|---|---|
| Deficient | Below 30 | Below 12 |
| Generally adequate | 50 or above | 20 or above |
| Potentially too high | Above 125 | Above 50 |
Food, sun and supplements
Few foods are naturally rich in vitamin D: fatty fish (salmon, trout, sardines), egg yolks and fortified milk or plant drinks are the main sources. Brief, sensible sun exposure in summer helps. For many people in northern climates, a supplement is the most practical way to meet their needs in the darker months. Vitamin D3 (cholecalciferol) is the same form your skin makes, and it is best absorbed when taken with a meal that contains some fat.
About CLE Vitamin D3 5,000 IU. One small capsule a day with a meal provides 5,000 IU of vitamin D3, which helps maintain immune function and healthy bones and teeth. Each bottle holds 90 capsules, a 3-month supply. Because this is a higher-strength dose, check with your healthcare provider that it is right for you, ideally based on a blood test.
This article is general information, not medical advice. Talk to your doctor or pharmacist before taking vitamin D supplements, especially if you have kidney disease, high calcium levels or take medication.