Assessments will be repeated immediately after ingestion, then at intervals post-ingestion as shown in the schematic. Breath symptoms will be measured every 30 minutes for 2 hours, then hourly. MRIs will be taken immediately post ingestion, then hourly for 6 hours. After 3 hours a meal will be provided, designed to be low in fermentable carbohydrate and fibre. This will stimulate gut motility and movement of small bowel content into the colon. The whole Study Day will last around 8 hours.