The proposed study aims to assess the efficacy and tolerability of adapting the CDED to the Mediterranean diet pattern, without compromising its key principles, namely the exclusion of ultra-processed foods with potential pro-inflammatory effects on the intestines. The decision to modify the CDED according to the characteristics of the Mediterranean diet pattern and to evaluate the potential of this modified version of the exclusion diet for Crohn's disease in terms of efficacy and tolerability are the main objectives of this study.

These objectives are driven not only by scientific evidence regarding the anti-inflammatory potential and protective role against chronic-degenerative diseases demonstrated by the Mediterranean diet but also to allow for greater adherence to Italian dietary traditions and improve compliance with the dietary regimen.

Furthermore, to date, there are no comprehensive multi-omic investigations integrating dietary data with microbiome, metabolome, and transcriptome profiles that can demonstrate the effect of the CDED at "omic" levels. A very recent study on pediatric patients shows interesting results regarding differential profiles of fecal metabolites after administration of CDE or NEE in different weeks of therapy.

Inclusion Criteria:

• Patients with a stable diagnosis of Crohn's disease according to the criteria of the ECCO/ESPGHAN guidelines.
• Patients with a new diagnosis of the disease or with a disease diagnosed no more than three years ago, receiving stable pharmacological therapy for at least 2 months with immunomodulators (thiopurines, methotrexate, azathioprine) or biologic drugs who have experienced a disease relapse and require reinduction of remission.
• Mild to moderate disease activity assessed by the wPCDAI score between 12.5-57.5 in the pediatric population and a Harvey-Bradshaw Index ranging from 5 to 16 for the adult population.
• Biochemical evidence of active intestinal inflammation at enrollment, assessed by inflammatory markers such as C-reactive protein (CRP) levels ≥ 0.5 mg/dl or fecal calprotectin ≥ 150 mg/g.
• Ability to provide biological samples (stool and blood samples).

Exclusion Criteria:

• Monogenic disease;
• Disease with fibrostenotic or penetrating phenotype;
• Complex perianal fistulizing disease not completely in remission;
• Patients with ileostomy or who have undergone intestinal resection or colectomy;
• Patients currently undergoing other nutritional therapy (e.g., exclusive enteral nutrition) or who have undergone it in the last month;
• Patients not on stable therapy with immunomodulators or biologic drugs or who started therapy with thiopurines less than 4 weeks before enrollment, or methotrexate less than 8 weeks before enrollment;
• Patients with recent use of systemic steroids in the four weeks before enrollment or recent initiation or dose adjustment phase of therapy with immunomodulators (e.g., azathioprine, 6-mercaptopurine, or methotrexate) or biologic drugs;
• Pregnancy;
• Vegan or vegetarian patients;
• Celiac disease.