Vitamin D, influenza link to be studied

~ March 4, 2008

By Tom Blackwell
National Post
www.nationalpost.com
Tuesday, March 04, 2008

It has already been touted as a simple protection against certain cancers. Now the Public Health Agency of Canada wants to study whether vitamin Dcould fight influenza, too.

The department has commissioned a novel study into the possible link between the nutrient and flu in senior citizens, suggesting a shortage of vitamin-producing sunlight may make Canadians more susceptible to the virus.

The agency has expedited contracting out of the research, saying in documents that it is "vital" to get working on it this flu season, since the results could lead to public-health recommendations on Vitamin D intake.

Although the possible connection is still very much in question, a recently published U.S. study suggested that taking large doses of the substance might be a dramatically effective shield against influenza.

"It think it's an important question to answer and really valuable," Dr. Alison McGeer, a flu expert at Toronto's Mount Sinai Hospital, said about the public health agency project.

"It could turn out to be nothing, it could turn out to be really complicated or it could turn out to be this lovely, simple answer. It's certainly worth doing."

The agency has contracted scientists at McMaster University in Hamilton, Ont., and Sunnybrook Health Sciences Centre in Toronto to conduct a pilot study of 200 senior citizens this flu season, leading to a larger project later.

It will look both at whether a deficiency in Vitamin D levels makes seniors more susceptible to the flu, and whether patients' genetic makeup affects the seriousness of flu infections.

Scientists have long wondered why influenza is so much more common during winter months, with theories ranging from the effects of colder temperatures, to the close proximity of people as they spend more time indoors.

Another hypothesis points to the fact that vitamin D levels are lower in winter, when bodies absorb less of the sunlight that helps generate the nutrient. It is believed that the vitamin plays an important role in "innate" immunity, the body's generic, hard-wired defences against infection.

The Canadian Cancer Society created a stir last June when it recommended adult Canadians take 1,000 IU of Vitamin D a day-- five times the current, government-recommended dose -- after an American study indicated it could cut the risk of breast, lung and colon cancer.

As for influenza, researchers at Winthrop University Hospital in New York recently reported intriguing results from a trial that was mainly focused on Vitamin D and bone loss in post-menopausalblack women. The researchers inadvertently discovered that women taking a placebo were more than three times as likely to get the flu or colds as those on vitamin D, though the number of subjects was relatively small. The difference was by far the most pronounced in winter, Winthrop's Dr. John Aloia wrote last October in the Journal of Epidomiology and Infection.

The Public Health Agency's study, already underway at Mc-Master University, will track 100 patients with severe cases of influenza, and 100 with relatively mild infections. The goal is to try to see what distinguishes the two groups, said Dr.Mark Loeb, a professor of pathology and molecular medicine who is helping lead the project.

Dr. Loeb's focus is the possible genetic reasons for why some people are more vulnerable to the virus, but he said the Vitamin D issue "is appealing from a public health point of view."

Despite the vitamin's early promise, Dr. McGeer said it is unlikely it will prove to be a magic bullet that banishes all cases of flu. At best, however, it could provide some extra protection against an even more feared health threat: a future pandemic flu strain with the potential to take a heavy death toll, she said.

Despite the growing attention on Vitamin D's potential health benefits and the cancer society's recommendation, there does not appear to have been a run on the stuff. Shoppers Drug Mart has seen a "small increase" in sales in recent months, a spokesman said yesterday.