Lucey 1987.

Methods	RCT with Cross‐over design
Participants	44 Patients Gastrointestinal outpatient clinic Manning criteria Mean age 32 years 68% female Mean duration of symptoms 60 months
Interventions	Bulking agent 3 months wheat bran fibre 13g/day
Outcomes	IBS symptom score, continuous
Notes	GI Outpatients No run‐in
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind, methods not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	16 patients dropped out. Reasons for withdrawal not reported
Selective reporting (reporting bias)	Low risk	Expected outcomes reported
Other bias	Low risk	The study appears to be free of other sources of bias