Vitamin D status of Canadians – from the Canadian Health Measures Survey

A Statistics Canada Report released in 2010 indicated that while 90% of Canadians 6- to 79-years old have enough Vitamin D in their blood for bone health, 10% (or roughly 3 million people) have concentrations considered to be inadequate and 1.1 million Canadians (or 4% of the population) is actually Vitamin D deficient; levels low enough to cause rickets in children and osteoporosis in adults. The highest prevalence of deficiency is in men aged 20 to 39 years old, with about 7% considered Vitamin D deficient.

A Statistics Canada Report released in 2010 indicated that while 90% of Canadians 6- to 79-years old have enough Vitamin D in their blood for bone health, 10% (or roughly 3 million people) have concentrations considered to be inadequate and 1.1 million Canadians (or 4% of the population) is actually Vitamin D deficient; levels low enough to cause rickets in children and osteoporosis in adults.  The highest prevalence of deficiency is in men aged 20 to 39, with about 7% considered Vitamin D deficient.

WHAT IS VITAMIN D?

Vitamin D is a fat-soluble vitamin that is naturally present in very few foods and is added to others (especially dairy products). Vitamin D is also produced in the body when ultraviolet rays from the sun makes contact with exposed skin and triggers vitamin D synthesis.

WHAT DOES VITAMIN D DO?

Vitamin D is essential for bone growth and bone remodeling but without sufficient vitamin D, bones can become thin, brittle, or misshaped. Together with calcium, vitamin D helps protect older adults from osteoporosis and children against rickets. Vitamin D is also known to be associated with a lower risk of breast and colon cancer, some cardiovascular disease and other diseases like multiple sclerosis.

HOW MUCH IS ENOUGH?

Vitamin D is measured in nanomoles per litre (nmol/L).

  • Levels below 27.5 nmol/L is are considered to indicate deficiency.
  • Levels below 37.5 nmol/L are considered inadequate for bone health
  • It is suggested that 75 nmol/L is optimal for overall health.
THE STUDY

“Vitamin D status of Canadians as measured in the 2007 to 2009 Canadian Health Measures Survey” was based on data from the Canadian Health Measures Survey (CHMS) which collected physical measures of health and wellness from a nationally representative sample of Canadians aged 6 to 79 years, including blood and urine samples.

Data

Data are from 5,306 individuals aged 6 to 79 years from all regions of Canada, representing all ages, both genders and all racial backgrounds. Measurement of Vitamin D as 25-hydroxyvitamin D [25(OH)D] concentrations were determined from blood tests, and factors known to affect vitamin D status were also assessed.

Findings

Ten percent of Canadians (or roughly 3 million people) have concentrations considered to be inadequate and 1.1 million Canadians (or 4% of the population) is actually vitamin D deficient; levels low enough to cause rickets in children and osteoporosis in adults.  The highest prevalence of deficiency is in men aged 20 to 39; with about 7% considered vitamin D deficient.

An estimated 4% of the population (5% of men and 3% of women) had levels indicating vitamin D deficiency.  The highest prevalence of deficiency (7%) was among men aged 20 to 39 years of age.

The report states that much higher concentrations (> 75 nmol/L) are needed for overall health and disease prevention and according to this report only 1/3 of people in Canada are above this level. 

Frequent milk consumption was related to better vitamin D levels in people of all ages; with those that drank milk more than once a day averaging 75 nmol/L.  Even with drinking milk more than once a day, vitamin D levels were still considered inadequate for overall health and disease prevention.   Those  that drank milk less than once a day had Vitamin D levels of 63 nmol/L

The average difference between people whose racial background was white (Caucasian) and people of other racial backgrounds was approximately 19 nmol/L, with whites having higher levels of Vitamin D.

SOURCES OF VITAMIN D

Vitamin D comes from foods and supplements, and from sun exposure.

Food Sources

There are only small amounts of vitamin D naturally occurring in foods such as oily cold-water fish (85 gm of light canned tuna contains 200 IU) and only a small amount of vitamin D is found in fortified foods such as milk (1 cup of milk contains 100 IU of vitamin D).

Sun Exposure

Vitamin D can be made by the body when the skin is exposed to sunlight. During the spring and summer months in Canada, daily sun exposure (if not wearing sunscreen or clothes that cover much of the body) may produce sufficient amounts of vitamin D, however many people avoid this due to the increased risk of skin cancer.

Even in sunny parts of Canada, Vitamin D production from the sun from late October to early March is insufficient and Vitamin D supplements are recommended.

As well, the skin’s ability to produce vitamin D drops with age, putting people older than 50 years of age, at risk.

Additional factors such as the time of day, amount of cloud cover, smog and the natural colour of one’s skin (melanin content) all affect the amount of vitamin D synthesis available.

VITAMIN D FROM THE SUN versus USE OF VITAMIN D SUPPLEMENTS

In northern climates, such as Canada which is above the 49th parallel, there are insufficient UV rays for 6 months of the year or more for adequate vitamin D synthesis.

The Canadian Cancer Society recommends that adults living in Canada should consider taking Vitamin D supplementation of 1,000 international units (IU) a day during the fall and winter months or year round if they are older (>50 years of age), have dark skin, don’t go outside often or if they do, wear sunscreen or clothing that covers most of their skin.

HOW DO I MAKE SURE TO GET ENOUGH VITAMIN D?

If you are an adult under the age of 50 years of age living in Canada, it is recommended that you supplement your diet with 1000 IU Vitamin D / day, more so if you are living in the Lower Mainland where there is often inadequate sunshine, even in the summer months.

Our Registered Dietitian can assess your diet and make recommendations to ensure you are getting sufficient micro-nutrients (vitamins and minerals), including Vitamin D.

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