Assessment of Allergy to Milk, Egg, Cod, and Wheat in Swedish Schoolchildren: A Population Based Cohort Study

Abstract

ObjectivesKnowledge about the prevalence of allergies to foods in childhood and adolescence is incomplete. The purpose of this study was to investigate the prevalence of allergies to milk, egg, cod, and wheat using reported data, clinical examinations, and double-blind placebo-controlled food challenges, and to describe the phenotypes of reported food hypersensitivity in a cohort of Swedish schoolchildren.MethodsIn a population-based cohort of 12-year-old children, the parents of 2612 (96% of invited) completed a questionnaire. Specific IgE antibodies to foods were analyzed in a random sample (n=695). Children reporting complete avoidance of milk, egg, cod, or wheat due to perceived hypersensitivity and without physician-diagnosed celiac disease were invited to undergo clinical examination that included specific IgE testing, a celiac screening test, and categorization into phenotypes of food hypersensitivity according to preset criteria. Children with possible food allergy were further evaluated with double-blind challenges.ResultsIn this cohort, the prevalence of reported food allergy to milk, egg, cod, or wheat was 4.8%. Food allergy was diagnosed in 1.4% of the children after clinical evaluation and in 0.6% following double-blind placebo-controlled food challenge. After clinical examination, children who completely avoided one or more essential foods due to perceived food hypersensitivity were categorized with the following phenotypes: allergy (29%), outgrown allergy (19%), lactose intolerance (40%), and unclear (12%).ConclusionsThere was a high discrepancy in the prevalence of allergy to milk, egg, cod and wheat as assessed by reported data, clinical evaluation, and double-blind food challenges. Food hypersensitivity phenotyping according to preset criteria was helpful for identifying children with food allergy.

Milk allergy is a minor cause of milk avoidance due to perceived hypersensitivity among schoolchildren in Northern Sweden

“…The prevalence of challenge‐proven milk allergy was likely to be even lower. In a previous study of this cohort, about half of the children categorised as having a current allergy to milk, egg, cod or wheat had a positive double‐blind food challenge .…”

Special diets are common among preschool children aged one to five years in south‐east Sweden according to a population‐based cross‐sectional survey

“…However, considering the previously shown large discrepancies between parent-reported and diagnosed food allergies (2,(4)(5)(6)(7)(8)(9)16,17), and the fact that many children on special medical diets lack medical certificates, some children may have been subjected to unnecessarily restricted diets. A potential way to avoid this may be the requirement for mandatory medical certificates for special diets for medical reasons, preferably with an appropriate time limit, for example for cows' milk and hens' egg allergies.…”

“…There are large discrepancies between parent-reported and physician-diagnosed food hypersensitivity, which might lead to unnecessary diet restrictions with potential negative effects on nutrition during an important period of growth and development (2,(4)(5)(6)(7)(8)(9)(16)(17)(18)(19). Unnecessary special diets can also result in additional costs and efforts for families and the preschools and schools their children attend (20).…”

Introduction of Complementary Foods to Infants

“…Most reports are based on self-reported food allergy, however, and it has been repeatedly shown that self-reported data will overestimate the prevalence as compared with evaluation by an oral food challenge [2][3][4] . It is estimated that IgE-mediated food allergy affects approximately 6-8% of children in developed countries [1,3,4] , thereby posing a significant burden on the afflicted children, their families, and the healthcare system.…”