Should we treat uncomplicated symptomatic diverticular disease with fibre?
Diverticular disease is a common gastrointestinal condition in older age groups. The prevalence is increasing with the ageing of our population, and diverticular disease in younger age groups also seems to be increasing.1 Among those affected, 10-25% will develop symptoms.2 Although diverticular disease and irritable bowel syndrome share the symptoms of pain and variable bowel habit, the proportion of cases of diverticular disease that meet strict criteria for irritable bowel syndrome varies from 14% to 51%,3 4 the lower figure being no different from the incidence in those with no diverticulosis. NHS patient information websites and leaflets and the standards committee of the American Society of Colon and Rectal Surgeons recommend fibre for recurrent, short lived, non-inflammatory abdominal pain and for preventing diverticulitis; the standards committee estimates the success of fibre in preventing recurrence of diverticulitis as >70%. 

However, although low intake of fibre is associated epidemiologically with an increased risk of developing diverticulosis, the recommendations for fibre as a treatment are based on weak evidence that is old, largely observational, and uncontrolled.2 5 Although Painter’s case series of 70 patients with diverticular disease who took two teaspoons of bran three times a day showed excellent resolution of symptoms, it lacked any control and so is unconvincing.6 There is also no good evidence for the amount or type of dietary fibre needed, and clinical experience suggests that bran fibre and green vegetables may worsen symptoms in some patients. This fits with data from randomised controlled trials in irritable bowel syndrome showing that bran increases flatulence7 and may well do the same in diverticular disease. Another randomised controlled …