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ARCHIVED - Research Related to the Prevalence of Food Allergies and Intolerances

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Canadian allergy prevalence study published in July 2010

Health Canada and AllerGen (Allergy, Genes, and Environment Network of Centres of Excellence) are supporting the SCAAALAR (Surveying Canadians to Assess the prevalence of common food Allergies and Attitudes towards food Labelling and Risk) study, a research initiative led by McGill and McMaster Universities. This large Canadian survey on the prevalence of food allergies was launched in June 2008. This study provide a better estimate of the prevalence of common food allergies in Canada as well as a better understanding of the attitudes and behaviours of those living with these medical conditions.

The first objective of the SCAAALAR study was to determine the prevalence of peanut, tree nut, fish, shellfish, and sesame allergy in Canada. The allergens that the study looked at are largely responsible for the majority of severe/fatal anaphylactic reactions. A random telephone survey was performed in the 10 Canadian provinces. Food allergy was defined as perceived (based on self-report), probable (based on convincing history or self report of physician diagnosis), or confirmed (based on history and evidence of confirmatory tests).

Of 10,596 households surveyed in 2008 and 2009, 3666 responded (34.6% participation rate), of which 3613 completed the entire interview, representing 9667 individuals. The prevalence data of perceived, probable and confirmed allergy are presented in the table (see below). The results indicate disparities between perceived and confirmed food allergy. The prevalence of confirmed allergy is the lower because 1) it is difficult to obtain results if performed and, 2) in many cases, there are no confirmatory tests available. Accordingly, many people self report having food allergy; however, they have not had the allergy confirmed by their healthcare provider. Wider use of confirmatory medical testing could contribute to more accurate diagnosis in those who report they have food allergies. Guidelines regarding increased use of confirmatory tests in general and food challenges in particular should be disseminated and might contribute to a more accurate diagnosis in those with an uncertain history of food allergy.

Prevalence estimates for perceived, probable, and confirmed food allergy

Children (%) (95% CI)
Peanut Tree nut Fish Shellfish Sesame
Perceived 1.77 (1.21-2.33) 1.73 (1.16-2.30) 0.18 (0.00-0.36) 0.55 (0.21-0.88) 0.23 (0.03-0.43)
Probable 1.68 (1.14-2.23) 1.59 (1.04-2.14) 0.18 (0.00-0.36) 0.50 (0.18-0.82) 0.23 (0.03-0.43)
Confirmed 1.03 (0.67-1.39) 0.69 (0.40-0.97) 0 0.06 (0.01-0.10) 0.03 (0.00-0.06)
Adults (%) (95% CI)
Peanut Tree nut Fish Shellfish Sesame
Perceived 0.78 (0.58-0.97) 1.07 (0.84-1.30) 0.60 (0.43-0.78) 1.91 (1.60-2.23) 0.07 (0.01-0.13)
Probable 0.71 (0.52-0.90) 1.00 (0.78-1.23) 0.56 (0.39-0.73) 1.69 (1.39-1.98) 0.05 (0.00-0.11)
Confirmed 0.26 (0.18-0.34) 0.35 (0.27-0.44) 0.12 (0.08-0.16) 0.71 (0.58-0.84) 0.01 (0.00-0.02)
Entire study population (%) (95% CI)
Peanut Tree nut Fish Shellfish Sesame
Perceived 1.00 (0.80-1.20) 1.22 (1.00-1.44) 0.51 (0.37-0.65) 1.60 (1.35-1.86) 0.10 (0.04-0.17)
Probable 0.93 (0.74-1.12) 1.14 (0.92-1.35) 0.48 (0.34-0.61) 1.42 (1.18-1.66) 0.09 (0.03-0.15)
Confirmed 0.61 (0.47-0.74) 0.68 (0.54-0.83) 0.10 (0.07-0.14) 0.73 (0.59-0.86) 0.03 (0.01-0.06)

The second part of SCAAALAR study also looked at the attitudes of the general public towards food allergy and the effectiveness of food labelling that alerts consumers to allergens in products. Once published, these findings will be vital in informing consumer safety around food allergy through improved labelling practices in Canada.

The information gathered from this study will help the government of Canada qualify health and educational resources needed to provide prevention, diagnosis and management of food allergies in Canada. It will also guide stakeholders in developing policies to prevent and manage anaphylaxis and assist food industries in making food labelling more consistent and comprehensible for allergic consumers and their family/social circle.