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Vitamin D sits on a shelf in a Dartmouth, N.S. drug store. A McGill University Health Centre report has revealed that over half of their study subjects were vitamin D deficient. ((Andrew Vaughan/Canadian Press))

A deficiency of vitamin D in study subjects has surprised doctors at the McGill University Health Centre.

A study, released Thursday, found that 59 per cent of study subjects had too little vitamin D in their blood and nearly a quarter of the group had serious deficiencies.

"Vitamin D insufficiency is a risk factor for other diseases," said Dr. Richard Kremer, the principal investigator of the study at the research institute.

"Because it is linked to increased body fat, it may affect many different parts of the body. Abnormal levels of vitamin D are associated with a whole spectrum of diseases, including cancer, osteoporosis, and diabetes, as well as cardiovascular and autoimmune disorders," he said.

How much vitamin D do I need?

The Canadian Cancer Society recommends Canadians take in 1,000 IU of vitamin D every day. During the spring and summer, that can be accomplished through normal daily exposure to the sun. In the fall and winter months, a vitamin D supplement may be necessary.

Deficiencies in the so-called "sunshine" vitamin have been linked to increased visceral fat, decreased muscle strength and overall health problems.

The new study, which is to be published in the March 2010 Journal of Clinical Endocrinology and Metabolism, is the first to show a clear link between vitamin D levels and accumulation of fat in muscle tissue.

"The lower the levels of vitamin D, the more fat in subjects," said Kremer.

Though the study shows a clear link, there is still no clear evidence that vitamin D supplementation could result in less fat in muscles or increased muscle strength.

"We need more research before we can recommend interventions," said Kremer.

Health Canada recommends adults 19 to 50-years-old need 200 international units (IU) of vitamin D per day. That includes pregnant and lactating women. Everyone over the age of 50 is advised to take a daily supplement of 400 IU of vitamin D.

The Canadian Cancer Society recommends taking 1000 IU of vitamin D a day in the fall and winter months.