Irritable bowel syndrome: assessment of psychological disturbance and its influence on the response to fibre supplementation.

This study describes the effect of fibre supplementation on the gastrointestinal symptoms and general wellbeing of patients with constipated irritable bowel syndrome. In a single centre, double blind, placebo controlled trial of 3 months duration, a daily supplement of 4.1 g fibre produced no greater change in gastrointestinal symptoms than placebo. Pretreatment constipation was related to baseline fibre intake. Overall outcome was the same in treated and control groups; a considerable placebo response was evident. This level of fibre supplementation is not a useful treatment; improving neither constipation nor other symptoms. At the outset pain severity correlated with depression score on psychometric testing. Those who felt better at the end of the study scored significantly lower for depression at outset than those who felt no better. In irritable bowel syndrome a depressive emotional state profile is a powerful determinant of outcome, shaping the response to treatment, which includes a considerable placebo element.