Women who are pregnant or breast-feeding should consider increasing their vitamin D intake to 2,000 international units a day to reduce the chances their children will develop such ailments as multiple sclerosis, diabetes and cancer later in life, the Canadian Pediatric Society says.
That amount of vitamin D is 10 times higher than what is currently recommended by Health Canada for women in their childbearing years, and the advice is believed to be the first time a medical group has called for healthy people to take such elevated amounts of the sunshine vitamin.
But it is the second time in recent months that a major Canadian public health advocacy group has decided the evidence for taking vitamin D has become so compelling that it is overstepping the government's recommendations.
In June, the Canadian Cancer Society said adults should take 1,000 IU a day. That call coincided with the release of a U.S. study that found taking the vitamin at levels above those deemed adequate by Health Canada reduced cancer risk by an astounding 60 per cent.
The pediatric society, representing doctors who specialize in children's health, is issuing the vitamin D advice in a position statement being released today in its journal, Pediatrics & Child Health. The statement said aboriginal people in particular are at higher risk of deficiencies of the vitamin.
The advice was based on the growing body of evidence that increased exposure to vitamin D during key points of fetal and infant development may offer protection against many dangerous diseases, including asthma, osteoporosis, dental cavities and inflammatory bowel disease, among others.
"New findings suggest that adequate vitamin D status in mothers during pregnancy and in their infants may have lifetime implications," the statement said.
As a precaution against being exposed to too much of the nutrient, the statement also recommended that women periodically have their doctors monitor their blood levels of the vitamin.
The new advice is likely to put additional pressure on Health Canada to undertake a timely review on whether its current advice is out of date.
Health Canada says 2,000 IU is the maximum amount that is safe to take each day, but it says a far lower amount - only 200 IU a day - is adequate for those aged 1 to 50.
Health Canada's advice was developed by a joint U.S.-Canadian expert panel, based on scientific evidence existing before 1997, although the federal agency has a separate recommendation calling for breast-fed children to be given 400 IU a day.
Mary Bush, director of Health Canada's nutrition policy and promotion office, said the government is aware that "significant evidence" has emerged since the late 1990s about the benefits of vitamin D. It is in active discussions with its counterparts at the U.S. Department of Health about the need to review current standards. Canada and the U.S. have a policy of developing common North American standards for nutrients.
"Until there is this comprehensive review on both benefits and safety, we stand by the current recommendations," Ms. Bush said.
Some vitamin D experts are urging the government to move quickly.
Reinhold Vieth, professor in the department of nutritional sciences at the University of Toronto and a leading international authority on vitamin D, says Health Canada's position "does create a loss of credibility" when major public health organizations take actions indicating its advice is outdated.
Vitamin D is called the sunshine vitamin because people make most of their body's supply naturally in naked skin exposed to strong sunlight during spring and summer.
The society's statement said that given the need for vitamin D, children and infants should be exposed to modest amounts of sunlight, which it estimated at less than 15 minutes a day.
Vitamin D is contained in most multivitamins, typically in amounts from 50 IU to 1,000 IU. Some foods, such as milk, are fortified with it, and it is also found in oily, cold water fish, such as salmon.
Complying with the pediatric society's advice would be practically impossible through diet alone because a woman would need to drink 20 cups of milk a day to reach the 2,000 IU level, indicating that those who wish to raise their levels will need supplements.