Table 1.

PICOS criteria for inclusion of studies

Parameter	Criterion
Participants	Patients with disease type: “Inflammatory bowel disease” OR “Crohn’s disease” OR “Ulcerative colitis”
Intervention	Fiber under study: {(“β-glucan” [Title/Abstract]) OR (“β -glucans” [Title/Abstract])} OR {(“Fructan” [Title/Abstract]) OR (“Fructans” [Title/Abstract])} OR (“Psyllium” [Title/Abstract]) OR (“Wheat bran” [Title/Abstract]) OR (“Oat bran” [Title/Abstract]) OR (“Germinated barley” [Title/Abstract]) OR {(“Non-digestible oligosaccharides” [Title/Abstract]) OR (“Resistant oligosaccharides” [Title/Abstract])} OR (“Non-starch polysaccharides” [Title/Abstract]) OR (“Cellulose” [Title/Abstract]) OR (“Hemicellulose” [Title/Abstract]) OR {(“Arabinoxylan” [Title/Abstract]) OR (“Arabinoxylans” [Title/Abstract])} OR {(“Arabinogalactan” [Title/Abstract]) OR (“Arabinogalactans” [Title/Abstract])} OR {(“Polyfructose” [Title/Abstract]) OR (“Polyfructoses” [Title/Abstract])} OR (“Inulin” [Title/Abstract]) OR {(“Oligofructan” [Title/Abstract]) OR (“Fructo-oligosaccharide” [Title/Abstract]) OR (“Fructo-oligosaccharides” [Title/Abstract])} OR {(“Galactooligosaccharide” [Title/Abstract]) OR (“Galactooligosaccharides” [Title/Abstract]) OR (“Galacto-oligosaccharide” [Title/Abstract]) OR (“Galacto-oligosaccharides” [Title/Abstract])} OR {(“Gum” [Title/Abstract]) OR (“Gums” [Title/Abstract])} OR {(“Mucilage” [Title/Abstract]) OR (“Mucilages” [Title/Abstract])} OR {(“Pectin” [Title/Abstract]) OR (“Pectins” [Title/Abstract])} OR (“Analogous carbohydrates” [Title/Abstract]) OR {(“Indigestible dextrin” [Title/Abstract]) OR (“Indigestible dextrins” [Title/Abstract])} OR {(“Resistant maltodextrin” [Title/Abstract]) OR (“Resistant maltodextrins” [Title/Abstract])} OR {(“Resistant potato dextrin” [Title/Abstract]) OR (“Resistant potato dextrins” [Title/Abstract])} OR {(“Synthesized carbohydrate compounds” [Title/Abstract]) OR (“Synthesised carbohydrate compounds” [Title/Abstract])} OR (“Polydextrose” [Title/Abstract]) OR (“Methyl cellulose” [Title/Abstract]) OR (“Hydroxypropylmethyl Cellulose” [Title/Abstract]) OR {(“Indigestible starch” [Title/Abstract]) OR (“Resistant starch” [Title/Abstract])} OR (“Lignin” [Title/Abstract]) OR {(“Wax” [Title/Abstract]) OR (“Waxes” [Title/Abstract])} OR (“Phytate” [Title/Abstract]) OR (“Cutin” [Title/Abstract]) OR {(“Saponin” [Title/Abstract]) OR (“Saponins” [Title/Abstract])} OR (“Suberin” [Title/Abstract]) OR {(“Tannin” [Title/Abstract]) OR (“Tannins” [Title/Abstract])} OR {(“Dietary fiber”) OR (“Dietary fibre”)}
Comparators
Outcomes	Disease status: “Exacerbation” [Title/Abstract] OR “Flare” [Title/Abstract] OR “Flares” [Title/Abstract] OR “Clinical remission” [Title/Abstract] OR “Remission” [Title/Abstract] OR “Clinical outcome” [Title/Abstract] OR “Clinical parameter” [Title/Abstract] OR “Mayo” [Title/Abstract] OR “CDAI” [Title/Abstract] OR “Crohn’s Disease Activity Index” [Title/Abstract] OR “CAI” [Title/Abstract] OR “Colitis Activity Index” [Title/Abstract] OR “SCCAI” [Title/Abstract] OR “Simple Clinical Colitis Activity Index” [Title/Abstract] OR “HBI” [Title/Abstract] OR “Harvey Bradshaw Index” [Title/Abstract] OR “Fecal calprotectin” [Title/Abstract] OR “Faecal calprotectin” [Title/Abstract] OR “Disease activity” [Title/Abstract] OR “CRP” [Title/Abstract] OR “ESR” [Title/Abstract] OR Endoscop* [Title/Abstract] OR Sigmoidoscop* [Title/Abstract] OR Colonoscop* [Title/Abstract]
Study design	Randomized controlled trial and report in English, German, or Dutch language.

The PubMed search terms have been used to describe the inclusion criteria.