How Much Do I Need?

Canadians can't make vitamin D from the sun in the winter

International experts on health recommended vitamin D levels be in the range of  100 nmol – 175 nmol/L (40 ng/ml – 70 ng/ml). To achieve these levels, people need to get adequate sun exposure, eat enough vitamin D rich food, or take supplements.

A blood test is the only way to determine a person’s current levels of vitamin D, and how much more they need to achieve and maintain good health.

One challenge is that some provinces, such as Ontario, Alberta and British Columbia, no longer routinely test vitamin D levels.

“The BC population is at risk of low vitamin D levels from autumn to spring. There is no clinical utility in performing vitamin D tests on patients who are thought to be at risk for sub-optimal vitamin D levels and who would benefit from vitamin D supplementation.” – Ministry of Health – Province of British Columbia

Private services are available for people keen to understand their body’s vitamin D level and determine a specific daily intake amount of vitamin D to achieve and maintain an optimal level.

In the absence of a blood test there are resources available to estimate a daily-recommended intake of vitamin D required to achieve an optimal blood serum level.

As a general rule 35-40 IU of vitamin D is required, per pound of weight, for a person to achieve an optimal vitamin D range.  Dr. Paul Veugelers of the University of Alberta School of Public Health crunched the numbers and shows his work in a series of charts to provide approximate ranges for IU daily intake.

While this provides a good guideline, it is important to remember factors such as height, weight, BMI and skin tone are all things that impact these guidelines and therefore a blood test is recommended as the most accurate way to determine a recommended daily intake.

Getting Vitamin D From the Sun

A number of calculators have been developed to help provide a general guideline of the amount of vitamin D absorbed through exposure to the sun.

This is one of the most robust calculators and has been used to create the following chart:

vitaminD (2)

Canada’s location creates a vitamin D ‘Feast-or-Famine’ environment.

When exposed to the summer sun the body is a vitamin D-making machine, creating upwards of 20,000 IU in less than 30 minutes.

Yet, with Canada’s northern latitude and proximity to the sun, Canadians aren’t able to generate vitamin D in the winter months (late October through early March). The angle of the sun in the winter months means not matter how many sunny days there are the vitamin D-soaked UVB rays aren’t powerful enough for people to make vitamin D from the sun’s rays.

“Within 10 to 20 minutes, without wearing sunscreen, people make between 10,000 and 20,000 IU (of vitamin D). But because of widespread sunscreen use, total sun avoidance, and our increasingly indoor lifestyles, our vitamin D levels have fallen drastically.” – Dr. John Cannell, founder of the Vitamin D Council

Getting Vitamin D From Food

Vitamin D does not naturally occur in most common foods. Some foods, like milk and cereal, have been fortified with vitamin D to help people get this important nutrient.

Food sources, with the level of vitamin D per serving.*

  • fortified milk (1 cup = 120 IU)
  • fortified cereal ( 1 cup = 40 IU)
  • salmon (3 oz = 794 IU)
  • sardines (100 grams = 193 IU)
  • egg yolk (1 = 37 IU)
  • ricotta cheese (1 cup = 25 IU)

(*approximate levels)


Getting Vitamin D From a Supplement

To get the amount of vitamin D required by the body many people take a supplement. While there are a number of online tools that can provide a recommended range of IU per day, a blood test is the best and only way to determine an individuals’ exact daily supplement amount needed to reach and maintain an optimal vitamin D level.


“I had never heard of taking Vitamin D before – I didn’t know the importance of that. The vitamins … are very good. I really like the program, it’s excellent.”

Elva Pena, Alberta
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