Blinded, placebo-controlled trials that compared probiotics with placebo in adults with irritable bowel syndrome were eligible for inclusion. Studies in children were excluded. The review assessed global symptoms, abdominal pain and distension, flatulence, colonic transit time, bowel habits and bacterial counts.
The included studies evaluated a variety of different probiotics (details were reported). Where reported, patients included people with Rome I and II criteria, Manning criteria, diarrhoea-predominant irritable bowel syndrome and constipation-predominant irritable bowel syndrome. Most patients in most studies were female (range 60 to 100per cent). In most studies the mean age ranged from 40 to 49 years; in one study patients were aged 25 to 70 years. Studies used different methods to assess outcomes; symptom scores were measured subjectively by patients or clinicians. In most studies, the duration of treatment was eight weeks or less.
The authors stated neither how papers were selected for the review nor how many reviewers performed the selection.