Background: Longitudinal data from population-based studies on the development and persistence of food hypersensitivity (FHS) during childhood are almost absent.
Methods: A population-based birth cohort was established, and information on various exposures and symptoms of allergic disease were obtained from questionnaires when the children were 2 months, 1, 2, 4 and 8 years of age. Complete data were available on 3104 children. Children with reported FHS and doctor's diagnosis of food allergy (RDFA) were identified and allocated into transient, intermittent, late-onset and persistent phenotypes. Food allergen-specific IgE-antibodies (abs) to a mix of six common food allergens (fx5) were analysed at 4 and 8 years of age in 1857 children.
Results: The overall prevalence of reported FHS in combination with RDFA should be 3.1% at 1 year to 7.6% at 8 years of age. However, reactions to milk, egg, fish and wheat decreased, whereas an increase was seen for peanuts and tree nuts. Reported reactions to egg, peanuts or tree nuts early in life, as well as IgE-abs to food allergens at the age of 4, increased the risk of FHS at 8 years of age. Furthermore, FHS at young ages increased the risk for asthma, eczema and allergic rhinitis at 8 years of age, even when adjustments were made for children with these symptoms during the first 2 years of life.
Conclusion: The increasing prevalence of FHS up to the age of 8 years probably reflects an increasing prevalence of allergy to birch pollen and pollen-related reactions to foods. Reactions to egg, peanuts and tree nuts early in life increase the risk of FHS at 8 years. Furthermore, reported FHS at young ages, even though transient, seems to increase the risk for other allergic diseases at 8 years of age.