Supplementary Material for: Comparative Safety of Baked Egg, Egg Yolk, and Egg White in Young Children with Egg Allergy

Introduction: Baked egg (BE) is generally well tolerated by children with egg allergy, and heated egg yolk (EY) is considered less allergenic than egg white (EW). Although these findings suggest that both BE and EY may be safer options for reintroduction, no studies have directly compared their safety with each other or with heated EW. This study aimed to compare the safety of oral food challenge (OFC) for reintroducing BE, EY, and EW in children with egg allergy.
Methods: We retrospectively analyzed data from patients who underwent OFCs with BE, EY, or EW at the Department of Allergy, Kanagawa Children's Medical Center, between 2014 and 2024. Only patients with a history of acute IgE-mediated allergic reactions (within 2 hours of egg ingestion), an egg white-specific IgE level ≥ 0.35 UA/mL, and strict avoidance of egg protein at the time of OFC were eligible for inclusion.
Results: Ninety-seven children under three years of age were enrolled (BE group, n = 47; EY group, n = 23; EW group, n = 27). The OFC positive rate was significantly lower in the BE group (0%) compared to the EY (17.4%) and EW (22.2%) groups (P = 0.0011). Although mild skin or gastrointestinal reactions were observed in the EY group, two patients in the EW group experienced respiratory symptoms. No patient required adrenaline administration.
Conclusion: OFC with a small amount of BE demonstrated a low positivity rate, and could be safely performed even in children with a history of egg-induced reactions.