Diet therapy (The 8×5 Diet) for adults living with bile acid diarrhoea: protocol for a feasibility randomised controlled trial.

introductionA national research priority for people living with bile acid diarrhoea (BAD) is effective treatment options to improve their quality of life. This study aims to evaluate the feasibility of conducting a randomised controlled trial (RCT) of a novel healthy dietary pattern (The 8×5 Diet) to inform a future, larger trial. METHODS AND ANALYSIS: We plan to enrol 76 UK adults living with BAD and ongoing diarrhoea using self-selection sampling and digital technologies. Eligible participants will be assigned to groups using permuted block randomisation using 1:1 allocation to receive either 8 weeks of usual care or The 8×5 Diet using one-to-one, dietitian counselling via a video-conferencing platform and developed digital resources. Randomisation, consent, recruitment, retention and acceptability will be evaluated using data from the RCT and post-trial interviews conducted with those in the intervention group. Secondary outcome exploratory assessment will include health-related quality of life, symptom relief, diarrhoea, diet quality, nutrient intakes and diet satisfaction. ETHICS AND DISSEMINATION: Ethical approval was granted by the University of Manchester Research Ethics Committee (2024-19094-33261; V1.7, last updated: 24/02/2025).Findings will be disseminated through peer-reviewed publication, conference presentation and social media. TRIAL REGISTRATION NUMBER: NCT06259396.