Clinical Research Directory

Inclusion criteria - CD study group: * Age ≥ 18 * Candidates for a medically-indicated, diagnostic colonoscopy due to suspected new-onset CD. * Naïve to any medical or nutritional intervention. Inclusion criteria - healthy controls: • Age- and gender-matched patients to the CD group, admitted for non-specific GI complaints (such as changes in bowel movements, bloating, abdominal pain) or routine screening for colorectal cancer as part of primary prevention per clinical guidelines. Exclusion Criteria - both groups: * Established diagnosis of inflammatory bowel disease (IBD) with prior treatment. * Chronic gastro-intestinal disorder (e.g. celiac disease, eosinophilic esophagitis, collagenous gastritis, autoimmune gastritis, etc.). * Type 1 or type 2 diabetes mellitus. * Past or present history of malignancy. * BMI \> 30 (kg/m2) * Use of systemic antibiotics or probiotics 2 months prior to enrolment. * Use of steroids 2 months prior to enrolment (not including a short course of topical steroidal therapy). * Any previous major gastric or intestinal surgery. * Suspected or proven extensive involvement of non-ileal small intestine or colon, or significant perianal disease. * Significantly stricturing or penetrating (fistulizing) disease at presentation. * Chronic treatment with any oral/systemic immunosuppressive or anti-inflammatory drugs (e.g. steroids, 5-aminosalicylic acid, immunomodulators, biologics, etc.). Patients receiving these drugs as inhalers/creams/ointments should not be excluded from the study. * Primary immunodeficiency. * Pregnancy or breastfeeding in the last 6 months. * Serious medical conditions that may alter the gut microbiome composition, based on investigators judgement (for example primary immunodeficiency, autoimmune disorder, or rheumatologic disease).