SOY ALLERGY IN ATOPIC CHILDREN

Background: Although soy is considered a major food allergen (along wi th milk, egg, peanut, fish, and wheat), the prevalence of soy allergy in the pediatric population is not well defined. Objective: To determi ne the prevalence of soy allergy in atopic children attending the Alle rgy Clinic at the Pediatric Department of Milan University. Methods: S even hundred four patients with allergic signs and symptoms, aged 1 mo nth to 18 years, were recruited between December, 1991 and April, 1992 . The subjects with positive skin prick tests to soy were tested using a DBPCFC with powdered soy formula in fruit juice, and rice or corn f lour as placebo. Ln children who refused the liquid challenge, capsule s containing dehydrated soy flour or talcum powder as placebo were adm inistered. An age-matched and sex-matched group of subjects with negat ive skin prick tests to soy were tested using an open challenge with s oy formula. Results: A positive skin prick test to soy was found in 14 8/704 patients (21%); 131 out of 148 children with positive skin prick test (group A) and 131 out of 556 children with negative skin prick t est to soy (group B) were challenged with soy: 8/131 (6%) in group A h ad a positive soy challenge while no clinical reactions were observed in children in group B. A younger median age, a positive past and curr ent personal history of cow milk allergy, and a previous history of so y allergy were found most often in children with positive soy skin pri ck test and positive soy challenge than in children with positive skin prick test and negative soy challenge. The eight soy-allergic childre n reacted to the soy challenge mostly with cutaneous and gastrointesti nal symptoms; symptoms were immediate in six and late in two children. The eliciting dose of soy was very small in the immediate reactions; higher and repeated doses were necessary for the onset of late reactio ns. Conclusion: The prevalence of clinical soy allergy in our children with positive skin prick tests to soy is 6.1% (8/131), while none of 131 children with negative skin prick test to soy reacted to the chall enge.