The role of exclusive enteral nutrition (EEN) in the induction of remission in pediatric patients with Crohn's disease had been well documented. But the role of EEN in children with Ulcerative Colitis (UC) was not clear. In this study, EEN will be combined with corticosteroids or infliximab in the induction of remission in pediatric UC patients with moderate to severe disease activity. The mucosal healing rate at week12 will be compared between the two groups (combine with EEN group VS non-combine group).

The role of exclusive enteral nutrition (EEN) in the induction of remission in pediatric patients with Crohn's disease(CD) had been well documented. Several randomized controlled trial studies found that the overall induction of remission was equipotent with EEN compared to corticosteroids for pediatric CD. However, in promoting mucosal healing and improving the nutritional status, EEN was much better than corticosteroids. But the role of EEN in children with Ulcerative Colitis (UC) was not clear. In this study, EEN will be combined with corticosteroids or infliximab in the induction of remission in pediatric UC patients with moderate to severe disease activity. The mucosal healing rate at week 12 will be compared between the two groups (combine with EEN group VS non-combine group).The sustained corticosteroid-free clinical remission rate and treatment modification rate during the first year will also be evaluated.

Inclusion Criteria:

1. Newly diagnosed UC
2. Years 6 to 18
3. Moderate to severe disease activity at diagnosis

Exclusion Criteria:

1. With mild disease activity at diagnosis
2. Had been treated with corticosteroids or biologics