The Role of NIchel and LTPs Sensitization in Functional Gastrointestinal Disorders: the NILT Study

Inclusion Criteria: * Age at least of 4 years * both sexes * history of functional dyspepsia (according to the Rome IV criteria, at least one symptom among the following - duration of symptoms greater than 4 days per month and for more than 2 consecutive months, feeling of post-prandial fullness, early satiety, pain and/or epigastric burning not associated with defecation - in the absence of organic disease) and irritable bowel syndrome (according to the Rome IV criteria, including all of the following criteria for at least 2 months prior to diagnosis - abdominal pain for at least 4 days per month associated with one/more of the following: change in EF, change in stool shape/appearance, if constipation is noticed, pain does not resolve with resolution of constipation - in the absence of organic disease). * written informed consent from the parents of the participants and the participants if over 6 years of age. Exclusion Criteria: * Age \< 4 years * Evidence of gastrointestinal pathology of organic nature (GERD, Helicobacter Pylori infection, eosinophilic diseases, celiac disease, chronic inflammatory bowel disease, chronic pancreatitis, cholelithiasis, neoplasia); motility disorder on a post-infectious basis; food intolerances (e.g. lactose), carbohydrate malabsorption, use of ASAs, NSAIDs; chronic systemic diseases (diabetes, amyloidosis, neuropathy) and autoimmune diseases; neuropsychiatric disorders; pregnancy.