Tuesday June 11 3:51 PM EST
By HELEN BRANSWELL
TORONTO (CP) - Canadians need more vitamin D.
And since Canada's climate and latitude doesn't allow most people to get adequate levels of the important nutrient the natural way year round - through exposure to ultra violet rays in sunshine - a more aggressive vitamin D supplementation program ought to be put in place, experts say.
"If we can't make it from sunlight exposure, then we need to be looking at whether we should be supplementing our foods more or advising people to take vitamin D supplementation," said Dr. David Hanley, head of the division of endocrinology and metabolism at the University of Calgary.
Hanley was the supervisor of a study looking at whether a group of Calgarians had adequate levels of vitamin D in their systems year-round.
The study, which was funded by the Health Research Fund of the Alberta Heritage Foundation for Medical Research, was published Tuesday in the Canadian Medical Association Journal. The lead author was Diana Rucker, a medical student at the university.
The researchers took and tested blood samples from 188 randomly selected Calgarians, testing them once per season. The blood samples were tested for several metabolic markers, including vitamin D metabolites and calcium.
Using conservative measures of what would be considered adequate, a third of subjects had insufficient levels of vitamin D during at least one of the seasons, they found.
When the researchers raised the bar and used a higher level now thought to be more indicative of adult vitamin D requirements, a whopping 97 per cent of participants showed a vitamin D deficiency at some point in the year.
The problem may be even more acute elsewhere, Hanley said.
Calgarians probably have the best conditions for natural vitamin D synthesis during winter of any Canadians, because of the city's high altitude and the fact that it has more hours of sunlight than any other city in the country.
An extended vitamin D deficiency causes rickets in children and a similar condition called osteomalacia in adults. Canadians aren't generally at risk of developing those ailments, but the lack of vitamin D may explain high levels of osteoporosis among people living in northern latitudes, Hanley said.
"The general feeling among bone experts and vitamin D experts has been mild vitamin D . . . insufficiency is a probable significant contributor to osteoporotic fracture."
And it's not just bone health people should be concerned about, said Reinhold Vieth, an expert on vitamin D.
In addition to helping in the absorption of calcium - which is crucial to healthy bones - vitamin D helps prevent certain cancers, multiple sclerosis and hypertension. Animal studies show it is important to immune function.
"When you actually look at it, there's like this grand panorama of effects that it does. There's a whole collection of diseases - preventing a variety of cancers for one thing, or preventing diabetes," said Vieth, a clinical biochemist at the University of Toronto and Mount Sinai Hospital.
He echoed the call for a recommendation that adult Canadians supplement their intake of vitamin D in a commentary that accompanied the study.
And Vieth noted even people who take fish oil pills or drink milk (which is fortified with vitamin D in Canada) aren't getting enough of the nutrient to do the trick.
There is no recommended daily allowance of vitamin D. Instead, there is what's known as an "adequate intake," a guideline of 400 units (nanomoles) a day based on the level that appears to prevent rickets in babies. That's what's found in milk, the standard fish oil pill and most multi-vitamins.
"We've thought that the amount of vitamin D that prevents rickets in a baby is all you need. And . . . it does nothing for a grown up," Vieth said.
He believes all adults should be taking 1,000 units of vitamin D a day,
from October to April. As it is hard get that amount of the vitamin through
diet - few foods contain vitamin D - he suggests buying and taking a 1,000-unit
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