Colonic diverticular disease causes a substantial healthcare burden, which is likely to increase as the elderly population grows.1 Little is known about who is affected by the disease, how often it occurs, and what the consequences are for patients. Nevertheless, the causes of diverticulosis, and the role of dietary fibre and a vegetarian diet, have been the focus of some small epidemiological studies.2 For example, in a study of 264 patients from the general population compared with 56 vegetarians, the vegetarians were less likely than the non-vegetarians to have radiologically confirmed diverticulosis (12% v 33%).3

For example, in a cross sectional study of 264 patients with confirmed diverticulosis, those with a vegetarian diet were less likely to have diverticulosis than non-vegetarians (12% v 33%).2 A cohort study of American healthcare professionals found that the insoluble component of fibre was associated with a decreased risk (relative risk 0.63, 95% confidence interval 0.36 to 0.75) of diverticular disease.4

The linked study by Crowe and colleagues (doi:10.1136/bmj.d4131) used data from the Oxford cohort of the …