Prevalence and clinical features of adverse food reactions in Portuguese adolescents

Abstract

Background & aimsThe objective of the present study was to determine, for the first time, the prevalence and clinical features of food allergy in Portuguese adolescents. MethodsCross-sectional study performed in various secondary schools in central Portugal. Randomly selected adolescents replied to a validated food allergy questionnaire. Those who reported an adverse food reaction were seen at participating hospitals, where clinical history was taken, skin prick (SPT) and prick-prick skin (SPPT) tests were performed, and food allergen-specific IgE levels (sIgE) were determined. An open oral challenge was performed in selected cases. Cases of positive clinical history of immediate (up to 2 h after ingestion) reaction in association with positive food sIgE levels and/or SPT were classified as IgE-associated probable food allergy and as confirmed IgE-mediated food allergy if food challenges were positive. Cases of positive clinical history of delayed (more than 2 h after ingestion) and negative food sIgE levels independently of positive SPT or SPPT results, were classified as non-IgE associated probable food allergy. ResultsThe prevalence of probable food allergy in Portuguese adolescents was 1.41% (95% CI: 0.90–2.03%), with fresh fruits, shellfish, nuts, and peanut as the most frequently implicated foods. IgE-mediated probable food allergy occurred in 1.23% (95% CI: 0.67–1.72%) of cases, with fresh fruits, shellfish, and nuts mainly involved. Cutaneous symptoms were most frequently reported. ConclusionsThe prevalence of probable food allergies in Portuguese adolescents is low, is mostly related to fresh fruits, shellfish, nuts, and peanut, and most frequently involves cutaneous symptoms.