How many Canadians have potentially deadly food allergies?

Nobody knows.

The knowledge gap will soon be resolved by a major study by the McMaster-based AllerGen, a national research network dedicated to reducing the impact of allergies and related immune diseases.

Today, there is no baseline information to say what proportion of the population has an allergy to one of the so-called big five foods: peanuts, tree nuts, shellfish, fish and sesame products.

McMaster's Susan Elliott, a medical geographer and co-leader of the study, said the survey of 3,000 Canadian households -- now about one-third complete -- will provide critical information.

"Not only are we looking at asthma and allergies and what causes them, but we're also looking at the impacts on society and what we can do about them," she said.

Health Canada has signed on as a funder of the study to accelerate the work that will show not only who's allergic to what, but also assess the level of understanding of sometimes confusing food labels and perceptions of the risks posed by food allergies in general.

The work could have a significant effect on food-labelling and other government policies.

While the immediate families of allergy sufferers are typically well-informed, often the other people in the lives of allergic children -- aunts and uncles, school officials, friends' parents, for example -- need more and clearer information, Elliott said.

Elliott is working with Montreal allergist Ann Clarke, using an interdisciplinary approach that combines medicine and social sciences.

Researchers are doing in-depth telephone interviews at 3,000 households across Canada.

They expect to finish gathering their data by the end of the year and to have a report ready by late 2009.

whemsworth@thespec.com

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