Detection of Metabolite Biomarkers for the Early Diagnosis and Prognosis of Cow's Milk Allergy in Children

In this study, fecal and urine samples will be collected from children diagnosed with : * IgE mediated cow's milk allergy, * suspected of a cow's milk allergy, but with negative diagnosis * IgE mediated food allergy other than cow's milk * healthy brothers and sisters of the first three groups A subset of patients with IgE-mediated cow's milk allergy will be asked to provide a urine and fecal sample yearly for prognostic purposes. The samples will be analyzed using a technique called metabolomics to identify biomarker candidates with diagnostic and/or prognostic potential. Additionally, microbiome analysis will be performed to map the microbiome of all groups.