Exploring the Experiences and Expectations of a Structured Low Fermentable Oligo-, Di-, Monosaccharide and Polyol Diet in People with Irritable Bowel Syndrome: A Qualitative Investigation

BACKGROUND: The low-fermentable, oligosaccharide, disaccharide, monosaccharide, and polyol (FODMAP) diet presents significant practical and behavioral challenges for managing irritable bowel syndrome (IBS). OBJECTIVE: To explore people's expectations and experiences across a dietitian-led low-FODMAP diet. DESIGN: Using a qualitative descriptive methodology, semi-structured interviews were conducted with 17 adults (mean age, 39.1 ± 15.1 years) with IBS (Rome IV criteria) who participated in a dietitian-led intervention. Participants completed 1 interview, conducted remotely via video or phone call in Australia (mean duration, 46 minutes), exploring expectations, experiences, and symptoms across all phases. Participants' sociodemographic data were collected. PARTICIPANTS/SETTING: Participants were purposively recruited between 2020 and 2022 from a community-based low-FODMAP diet parent trial exploring psychological predictors of symptom response to dietary management. Eligible participants consented to future research contact from the parent trial, had English proficiency, and provided informed consent. ANALYSIS: Two researchers conducted an inductive thematic analysis, constructing key themes on expectations and experiences of the low-FODMAP diet, identifying barriers and enablers to completion. RESULTS: Four themes were constructed: (1) Past experiences with IBS and health interventions and services underpinned expectations; (2) Diverse expectations and experiences across each FODMAP phase; (3) The low-FODMAP diet required significant planning, effort, and motivation, leading to cognitive and emotional burden; (4) Integrating dietary and health learning into daily life post-trial. CONCLUSIONS: The low-FODMAP diet is complex, with personal expectations, symptom response, and psychological factors influencing adherence and perceived success. These findings underscore the importance of a person-centered approach that considers an individual's contextual factors to support completion.