Food allergies affect 7.5 percent of Canadians, finds nationwide study

22-Sep-2010 - Last updated on 23-Sep-2010 at 11:30 GMT

One in 13 Canadians suffers from a food allergy, according to researchers who claim to have conducted the first nationwide study to determine the prevalence of severe food allergies in Canada.

The study, published in the Journal of Allergy and Immunology, found that many Canadians are not properly diagnosed and experience repeat exposure to allergens, putting them at increased risk of anaphylaxis.

“Our study found that a significant gap exists between healthcare providers’ and patients’ perceptions about proper diagnosis and management of food allergy,” said Dr. Ann Clarke, allergist at the McGill University Health Centre and co-author of the study.

The researchers collected data on 9,667 individuals across Canada by telephone interview about allergies to peanut, tree nut, fish, shellfish and sesame – the allergens “largely responsible for the majority of severe/fatal anaphylactic reactions”, according to the authors. They used a version of a questionnaire developed for a 2002 study that aimed to determine food allergy prevalence in the United States, modified to include sesame.

“There have been a few population-based studies estimating the prevalence of peanut, tree nut, fish, and shellfish allergies in the United States, but no such studies have been conducted in Canada,” they wrote.

The researchers found that prevalence of probable allergy to peanut, tree nut, fish, shellfish, or sesame – a small portion of all potential food allergens – in the Canadian population was 3.2 percent. Individual probable prevalence results were: peanut allergy, 0.93 percent; tree nut, 1.14 percent; fish, 0.48 percent; shellfish, 1.42 percent; and sesame, 0.09 percent.

Clarke said: “Many people self report having food allergy; however, they have not had the allergy confirmed by their healthcare provider. This finding underscores the importance of proper diagnosis and management of food allergy by a health professional, as many of the study participants with food allergy had experienced at least one repeat reaction and very few had been managed properly.”

The researchers said that hospitalizations because of food-induced anaphylaxis are reported to have increased by 350 percent over the past decade, and further research is needed to explore the role of environmental factors in the development of food allergies.

Source: Journal of Allergy and Clinical Immunology

doi:10.1016/j.jaci.2010.03.015

“A population-based study on peanut, tree nut, fish, shellfish, and sesame allergy prevalence in Canada”

Authors: Moshe Ben-Shoshan, Daniel W. Harrington, Lianne Soller, Joseph Fragapane, Lawrence Joseph, Yvan St Pierre, Samuel B. Godefroy, Susan J. Elliot, and Ann E. Clarke.