ABSTRACT
BACKGROUND: Altered motility and threshold for pain have been incriminated in the pathogenesis of the irritable bowel syndrome (IBS). Capsaicin affects visceral sensory perception and chillies, which contain capsaicin, have been shown to accelerate gut transit. AIMS: To evaluate the effect of red chillies on small bowel transit (SBT) and colonic transit (CT) and rectal sensitivity in normal men and men with IBS. METHODS: Twenty-nine men with IBS diagnosed using Manning's criteria, and 21 healthy men, were studied before and after ingestion of 10 g red chilli powder (capsaicin equivalent 14 mg). SBT time was measured as the time taken for 99mTc-sulfur colloid to reach the cecum after leaving the stomach. Total and segmental CT times were assessed using radio-opaque markers. Rectal sensitivity and pain threshold to intrarectal balloon distension were measured. RESULTS: The median (range) bowel frequency in patients and healthy men was 2 (1-6) and 1 (1-3) per day (p=0.03), respectively. After ingestion of chillies, it increased to 3 (1-8) per day and 2 (1-4) per day (p=0.01), respectively. There was no difference in transit times between patients and healthy men; chilli ingestion did not alter SBT time, total or segmental CT time. IBS patients had a lower threshold to balloon distension for both discomfort and pain in the basal state (p<0.01). Chillies increased this threshold in healthy men (p<0.01). CONCLUSIONS: Men with IBS do not have SBT or CT abnormalities, but have a lower rectal balloon sensitivity threshold. Chilli powder does not alter either SBT or CT in men with IBS or healthy men; however, it increases the rectal threshold for pain in the latter.