The Adequacy of Habitual Dietary Fiber Intake in Individuals With Inflammatory Bowel Disease: A Systematic Review.

BACKGROUND:Dietary fiber may influence disease course in individuals with inflammatory bowel disease (IBD), yet there is a paucity of understanding of habitual fiber intakes. OBJECTIVES:To identify studies measuring fiber intakes of individuals with IBD, compare the adequacy of fiber intakes with that of control groups or respective national dietary guidelines, and examine factors associated with fiber consumption. METHODS:Five electronic databases-MEDLINE, CINAHL, SCOPUS, PROQUEST, and COCHRANE LIBRARY-were systematically searched, using search terms inflammatory bowel disease, Crohn's disease, ulcerative colitis, dietary intake, and fiber, until December 2019, with hand searching of reference lists. Primary studies were included if fiber intakes were measured in participants 18 years of age or older, with confirmed IBD, with or without comparison to a control. RESULTS:A total of 2105 publications were identified, and 26 met inclusion criteria. Total fiber intake of 4164 participants with IBD ranged broadly (9.9 ± 7.8 g/day to 21.0 ± 10.5 g/day). Most (18/26) used cross-sectional study design, with a large degree of heterogeneity in tools measuring fiber intake. Sixty-six percent of studies comparing participants with IBD with control groups found that participants with IBD consumed significantly less fiber than control subjects. Four studies reported that less than 10% to 21% of IBD participants met their national fiber recommendations. Data conflicted regarding an association between disease type, disease activity, or rate of relapse and fiber intake. CONCLUSIONS:Individuals with IBD consume less fiber than healthy populations. Fiber intakes are inadequate compared with respective national fiber guidelines. Interpretation of factors associated with fiber intakes were limited by data quality and conflicting results. Future research is required into factors associated with fiber intake and whether increasing fiber intakes can influence disease course and behavior.