Green Tea in Crohn's Disease

Inclusion Criteria: * Women and men ≥ 18 years with signed informed consent, * Patients with proven Crohn's disease, * Chronic-active course ≥ 3 months, * Current CDAI ≥ 150 and ≤ 350, * All medications for Crohn's disease have to be on a constant dosage for at least 4 weeks prior to study entry (i.e. 5-ASA, steroids), * Ability of the participant to understand character and individual consequences of the study. Exclusion Criteria: * Pregnancy or the wish to become pregnant, breastfeeding, * Concomitant treatment with methotrexate, azathioprine or 6-mercaptopurine for \< 3 months, * Treatment with TNF-alpha-antagonists, cyclosporine or tacrolimus \< 4 weeks prior to study entry, * Participation in another study within the last 4 weeks, * Ulcerative colitis or indeterminate colitis, * Infectious colitis, including cytomegalovirus or Clostridium difficile induced colitis, * Colitis for other reasons like known diverticulitis, radiation colitis, ischemic colitis or microscopic colitis, * Malabsorption syndromes, lactose intolerance, celiac disease, exocrine pancreas insufficiency, * Bleeding hemorrhoids, * Other inflammatory or bleeding disorders of the colon and intestine, or diseases that may cause diarrhea or gastrointestinal bleeding, * Intolerance / aversion to tea and/or coffee, * Current treatment with antibiotics.