Actually just saw a review in "Inflammatory Bowel Disease" journal. In addition to giving more comfortable stool (symptom help) there may also be a small anti-inflammatory benefit (disease help).
Fiber in the Treatment and Maintenance of Inflammatory Bowel Disease: A Systematic Review of Randomized Controlled Trials said...
Abstract
Background: Dietary fiber may favorably influence fermentation, gastrointestinal inflammation, and disease progression in Crohn's disease, ulcerative colitis (UC), and pouchitis and offer an attractive therapeutic addition to pharmacological treatment. This systematic review appraised data from randomized controlled trials of fiber in the management of inflammatory bowel disease.
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Conclusions: There is limited weak evidence for the efficacy of fiber in improving disease outcomes in UC and pouchitis. The potential antiinflammatory role of fiber is intriguing and merits further investigation in adequately powered clinical trials. Excluding overt gastrointestinal obstruction, there was no evidence that fiber intake should be restricted in patients with inflammatory bowel disease.