Bacteria & Inflammation in the Gut (BIG) Study

Exclusive Enteral Nutrition (EEN) is the liquid diet given to children with active Crohn's Disease (CD). EEN has previously been shown to induce changes in major bacterial metabolites and dominant bacterial species which are more profound in children that clinically improve. This study aims to determine whether it is possible to maintain these bacterial changes with prolonged supplementary enteral nutrition (SEN) while returning to normal diet and if this can reduce risk of subsequent relapse for children with CD. New technologies will allow measurement of a broad range of bacteria and metabolites, to test if the clinical response to EEN and changes in gut inflammation are associated with bacterial composition and chemical products; and if maintenance of changes using SEN reduces the risk of relapse over a 12 month period. The study will aim to recruit all potential Crohn's disease children coming to a tertiary paediatric centre for colonoscopy. Once consented, an initial blood, urine and faecal sample will be requested along with 8 mucosal biopsies during the routine endoscopy session. If diagnosed with CD, and if the clinician prescribes treatment with EEN, an additional blood sample will be requested at the end of EEN, and 5 faecal and urine samples spread over 12 months; as well as some dietary information. Samples will be collected from up to 42 children with CD and 42 age- and sex-matched healthy volunteers. Initial samples taken from children who were not diagnosed with CD will be compared with CD samples to look for potential metabolic disease markers. Characterisation of faecal bacteria and metabolites in both faeces and urine; as well as measurement of blood inflammatory biomarkers will be performed.