Evaluation of the Efficacy and Tolerability of an Exclusion Diet in Patients With Juvenile Idiopathic Arthritis

Inclusion Criteria: * Confirmed diagnosis of juvenile idiopathic arthritis (JIA) in the forms of enthesitis-related arthritis and oligoarticular forms according to the ILAR 2001 criteria (https://medicalcriteria.com/web/reujia/); * Age between 6 and 18 years (not yet 18); * Active disease of mild to moderate severity, assessed through the Juvenile - Arthritis Disease Activity Score (JADAS10) tool (Trincianti C. et al., American College Rheumatology, 2021); * For study groups 2 and 3: failure of ongoing pharmacological therapy at the time of screening, defined as a failure to achieve at least a 20% reduction in JADAS10 values after 3 months of initiating DMARD therapy or biologic medication, or if the disease is inactive on such therapy, a 20% increase in those values; * Signed informed consent. Exclusion Criteria: * Patients requiring systemic immunosuppressive therapy for active uveitis; * Patients undergoing therapy with systemic corticosteroids (defined as prednisone equivalent \>0.5 mg/kg for \>7 days) or intra-articular corticosteroids in the 3 months prior to enrollment; * Patients with fecal calprotectin values \> 250 mcg/g at the time of screening; * Use of antibiotics in the month prior to enrollment.