Prevalence and Risk Factors for Walnut and Cashew Nut Sensitization in Preschool Children with Food Allergies in Japan.

Introduction: The incidence of tree nut allergies, including walnut and cashew nut allergies, has increased significantly globally. In Japan, these allergies rank third after egg and milk allergies and are associated with high rates of anaphylaxis. Jug r 1 and Ana o 3 are effective biomarkers for diagnosing walnut and cashew nut allergies. However, sensitization rates and risk factors among preschool children remain underexplored. This study aimed to investigate the prevalence of Jug r 1-sIgE and Ana o 3-sIgE sensitization, as well as their associated risk factors, in this population.

Methods: This retrospective study was conducted at four hospitals in Chiba Prefecture and included preschool children under 7 years diagnosed with food allergies and without prior tree nut consumption. Sensitization was defined as a specific IgE level of ≥0.35 IU/mL. Clinical data, including allergic conditions, were analyzed, and logistic regression was used to identify the risk factors for sensitization.

Results: Among 248 children, Jug r 1-sIgE and Ana o 3-sIgE levels were measured in 198 and 215, respectively. Jug r 1 sensitization peaked at 34.0% in the 3-4-year group, while Ana o 3 sensitization peaked at 12.2% in the 5-6-year group. Cashew, peanut, and wheat allergies were identified as major risk factors for Jug r 1 sensitization, whereas peanut, walnut, and wheat allergies were associated with Ana o 3 sensitization.

Conclusion: Jug r 1-sIgE and Ana o 3-sIgE sensitization are prevalent in high-risk preschool children in Japan. Early screening and personalized management strategies are essential for managing tree nut allergies.