This study will evaluate a novel diet for adult crohn's disease patients (The Crohn's Disease Exclusion Diet - CDED). Half of the patients in this study will receive the CDED alone while the other half will receive the CDED and a liquid diet formula, for 24 weeks.

Environmental factors, the microbiome (bacteria in our gut) and innate immunity all play a role in the pathogenesis of Crohn's disease .Exclusive enteral nutrition (EEN) was found to be effective for inducing remission in active pediatric Crohn's disease, while Partial Enteral Nutrition (PEN) with free diet was not; suggesting that the mechanism of EEN depends on exclusion of dietary components. Dietary factors may play a role in the pathogenesis of the disease, and maybe an important under-investigated therapeutic target.

"The Crohn's Disease Exclusion Diet" (CDED) is a palatable diet excluding components suspected to interfere with the bacteria in our gut or impair immune mechanisms. Our group previously evaluated 47 patients using the Crohn's disease Exclusion Diet + 50% Polymeric formula for 6 weeks, and demonstrated a 78% response rate and 70% disease remission rate using stringent criteria. This was accompanied by a highly significant reduction in markers for inflammation (C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR)), and normalization of CRP in 70% of those entering remission. Among these patients were 13 adults aged 19-32, the remission rate in these 13 patients was 69%, similar to the pediatric data. Importantly, 6/7 patients in this study who refused to drink formula and just used the diet achieved remission, suggesting that the exclusion and not partial enteral nutrition are responsible for the high remission rate. Our former study did not evaluate mucosal healing as an end point, since performing colonoscopies after 6- 12 weeks of therapy is neither ethical nor feasible in children.

At present, data about nutritional therapy and this new dietary approach have been generated primarily in children, and this new diet has not been evaluated for early mucosal healing. The objectives of this pilot study are to generate data in adults, evaluate the diet over a longer period of time (24 weeks) and evaluate mucosal healing. The study is a prospective open label randomized controlled pilot trial in adults, with mild to moderate Crohn's disease who will receive the Crohn's Disease Exclusion Diet (CDED) for 24 weeks.

If effective, this could enable use of a feasible, safe intervention for induction and maintenance of remission as a new therapy or as an adjunctive therapy with medical therapy.

Inclusion Criteria

1. Informed consent
2. Established Crohn's disease
3. Aged 18-55
4. Duration of disease up to 5 years
5. Harvey Bradshaw Index 5 ≤( HBI) ≤15
6. Patients with uncomplicated disease involving the terminal ileum and or cecum
7. Patients who performed colonoscopy (or MR/CTEnterography with elevated calprotectin>200) demonstrating active disease in the previous 8 weeks

Exclusion Criteria

1. Patients with severe Disease (HBI > 15) or HBI<5
2. Pregnancy,
3. Patients with active extraintestinal disease, current B2 (Fixed non inflammatory stricture1 or small bowel obstruction) or B3 disease,
4. Patients who used immunomodulator <8 weeks, or had dose changed in past 8 weeks,
5. Patients with current or past use of biologics, or use of systemic steroids2,
6. Patients with deep ulcers involving the colon distal to the splenic flexure on most recent colonoscopy
7. Any proven current infection such as positive stool cultures or positive tests for parasites or C. difficile. Stool tests are mandatory only if diarrhea is present.
8. Active Perianal disease ( clarification-fistula with discharge or abscess)
9. Patients who have undergone an intestinal resection
10. Patients with systemic disease including: type 2 diabetes, kidney failure, liver failure, neurological disease, active heart disease and patients with active autoimmune condition requiring medication3
11. Patients unwilling to consume any animal source protein (eggs, chicken or fish).

Comments:

1. Patients with ileo-cecal valve narrowing maybe included

2. Patients active despite budesonide may enter the trial if they are on 3 mg, and stop budesonide within 14 days of commencement of the trial.

3. Patients with Celiac disease or Hashimoto Thyroiditis can be enrolled

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