Review of exclusive enteral therapy in adult Crohn's disease

Background Exclusive enteral nutrition (EEN) is a potentially effective but underused therapy for Crohn's disease (CD) in adults. It is first-line induction treatment for paediatric patients but remains a second-line or third-line therapy in adults. Objective To analyse the evidence for EEN in adult patients with CD, and summarise this in a narrative review. Methods In April/May 2020 and July 2021, a literature search was performed using the Medical Subject Headings (MeSH) terms: 'Crohn's disease', 'CD', ' inflammatory bowel disease', ' IBD', ' exclusive enteral nutrition', ' enteral nutrition', ' EEN', in PubMed, Scopus, Cochrane. Additional studies were obtained from references of search result articles as well as general reading. Studies with adult patients with CD treated with EEN were selected. 79 articles of relevance were found. Where data in adults were lacking, data from paediatric studies as extrapolated with care. Results EEN in adult patients been shown to improve clinical, biomarker, endoscopic and radiologic measures of disease activity. EEN avoids the potential adverse effects of recurrent corticosteroids for induction such as metabolic derangements and opportunistic infections. EEN has also demonstrated benefits among adult patients with fistulising and stricturing CD. It may avoid surgery in such patients. Preoperative EEN has also been shown to reduce postoperative complications and recurrence. There appears to be benefits in combing EEN with antitumour necrosis factor agents, however, benefits of combination therapy with other biologics are less clear. A major drawback of EEN therapy in adults has been poor compliance. More palatable polymeric formulations improved patient education and dietitian support may overcome this. Evidence in adults is limited to small studies, often with suboptimal control arms and lack of blinding. Larger scale studies with improved study design are needed to confirm these beneficial effects. Conclusion Despite limitations in evidence EEN should be considered in treating adults with CD.