Introduction Vegetarians and those consuming a high fibre diet are thought to have a lower risk of diverticular disease but there is little evidence from prospective studies to substantiate these associations. The objective was to examine the associations between vegetarianism and dietary fibre intake with the risk of diverticular disease in the EPIC-Oxford study.

Methods This analysis of the EPIC-Oxford cohort included 47 033 men and women living in England or Scotland of whom 15 459 (33%) were vegetarians. Diverticular disease cases were identified through linkage with hospital records. The RR of diverticular disease by vegetarian status and quintiles of dietary fibre intake was estimated using multivariate Cox proportional hazards regression models.

Results After an average follow-up of 11.6 years, there were 812 incident cases of diverticular disease. Vegetarians had a 30% lower risk (RR=0.70; 95% CI 0.56 to 0.87; P_{heterogeneity}=0.001) of developing diverticular disease compared with non-vegetarians. There was also an inverse association with fibre intake; participants in the highest quintile (>25 g/day) of dietary fibre intake had a 41% lower risk (RR=0.59; 95% CI 0.46 to 0.78; P_trend <0.001) compared to those in the lowest quintile (<14 g/day). After mutual adjustment, both a vegetarian diet (P_{heterogeneity}=0.015) and a higher intake of fibre (P_trend =0.001) were significantly associated with a lower risk of diverticular disease.

Conclusion Consuming a vegetarian diet and a high intake of dietary fibre were both associated with a lower risk of diverticular disease.