Effects of Exclusive Enteral Nutrition on Bone Mass, Linear Growth and Body Composition in Children with Crohn’s Disease Francisco A. Sylvester Exclusive enteral nutrition (EEN) consists of substituting all food for a defined, commercially available formula for 6–8 weeks to induce remission in Crohn’s disease. The efficacy of EEN to induce remission in Crohn’s disease is similar to that of oral glucocorticoids, and EEN has a much better safety profile than pharmacological therapies for Crohn’s disease. For these reasons, EEN is first-line therapy for most children newly diagnosed with Crohn’s disease in Australia and Europe, but is infrequently used in North America. Barriers to the use of EEN in the United States include physician and patient attitudes, the monotony of the diet and the need to insert a feeding tube for its administration in most patients. Polymeric formulas which are more palatable and economical than elemental or semi-elemental formulas can be used in EEN and are therapeutically equivalent. Continuous overnight administration and intermittent boluses have similar efficacy to treat Crohn’s disease. Cyclical EEN may be used for maintenance therapy. The mechanisms of action of EEN are not known. They are thought to include nutritional reconstitution, modification of the microbiome, provision of nutrients to the intestinal epithelium and a decrease in the array of protein antigens offered to the intestinal mucosa. In children with Crohn’s disease, EEN induces rapid weight gain. EEN corrects deficits in lean body mass, stimulates bone modeling and remodeling (improving bone mass and bone geometry), and may promote linear growth. However, these effects appear to be limited to the period when EEN is administered. Maintenance regimens that include enteral nutrition (EN), even when not exclusive, may sustain these benefits. EN may also be an adjuvant to treatment with infliximab. Studies in adults with Crohn’s disease show that, above a certain threshold of nutritional supplementation (at least 30–40% of daily calories), response to maintenance infliximab is more sustained than if infliximab is used alone. 22 In summary, EEN is an effective therapy to induce and maintain remission in Crohn’s disease, but is currently underutilized in the United States. EEN has many nutritional benefits and improves bone mass, bone architecture and body composition, at least short term. However, sustaining these benefits may require using EN as adjuvant therapy for Crohn’s disease on an ongoing basis. 23