Inclusion Criteria:  Adult patients (18-80 years) active inflammation of terminal ileum and/or colon with a Simple Endoscopic Score for Crohn's Disease (SES-CD) greater than 5 (or greater than 3 for patients with isolated ileitis), patient reported outcome 2 (PRO2 - 7 day average daily stool frequency x 2 + 7 day average daily abdominal pain score x 5) > 8, faecal calprotectin above 250 µg/g.  Exclusion Criteria:  Abcess, Bowel resection within 6 months before enrolment, Ostomy, Short-bowel syndrome, Clinically significant stricture that could require surgery, Pregnant, Lactating woman or desire to become pregnant during the study, Unwilling or unable to follow the study diet.