A Randomized Controlled Trial of Oral Immunotherapy Versus Allergen Avoidance in Children Under 2 Years With Food Allergy

The goal of this clinical trial is to learn whether oral immunotherapy (OIT) is safe and effective for treating food allergy in children aged 0-2 years with peanut, tree nut, or sesame allergy. The study also aims to identify biological mechanisms and biomarkers associated with natural tolerance development and successful OIT using a systems biology approach. The main questions it aims to answer are: 1. Does oral immunotherapy increase the likelihood of successful desensitization and sustained unresponsiveness compared with allergen avoidance? 2. Can immune, microbiome, metabolomic, genetic, and epigenetic profiles predict treatment response, natural tolerance development, and long-term outcomes? Researchers will compare children receiving oral immunotherapy with children receiving standard care (allergen avoidance) to determine differences in treatment success, sustained unresponsiveness, safety, quality of life, and biological markers. Participants will: * Be randomized to either oral immunotherapy or allergen avoidance for 18-24 months. * Undergo oral food challenges at study visits to assess allergic reactivity and treatment outcomes. * Provide blood, urine, hair, skin swabs, skin tape strips, throat swabs, nasal lining fluid, and stool samples at baseline and at the end of the study for immune, microbiome, metabolomic, gene expression, and epigenetic analyses. * Complete allergy assessments, including skin prick testing and clinical evaluations. * Have allergic symptoms, adverse reactions, and development of other allergic diseases monitored throughout the study. * Have parents complete questionnaires assessing food allergy-related quality of life, anxiety, and coping.

Inclusion Criteria: * Children age 0-2 years * Diagnosed IgE-mediated food allergy to tree-nuts, sesame, and/or peanuts, defined as: Positive oral food challenge (OFC) at inclusion or within 6 months before AND positive SPT (≥ 3 mm) or specific IgE (≥ 0.35 kUA/L) * Both parents provide informed consent Exclusion Criteria: * Already undergoing any form of immunotherapy * Already undergoing any form of biological treatment * Medical conditions precluding OITs: Uncontrolled asthma, atopic dermatitis requiring systemic therapy, eosinophilic esophagitis (EoE) and other GI-diseases, other severe immunological diseases (e.g. inborn errors of immunity )