Constipation and a low-fiber diet are not associated with diverticulosis

Asymptomatic diverticulosis is commonly attributed to constipation caused by a low-fiber diet, although evidence for this mechanism is limited. We examined the associations between constipation and low dietary fiber intake with risk of asymptomatic diverticulosis.

We performed a cross-sectional study that analyzed data from 539 individuals with diverticulosis and 1569 without (controls). Participants underwent colonoscopy and assessment of diet, physical activity, and bowel habits. Our analysis was limited to participants with no knowledge of their diverticular disease to reduce the risk of biased responses.

Constipation was not associated with an increased risk of diverticulosis. Participants with less frequent bowel movements (<7/wk) had reduced odds of diverticulosis compared with those with regular bowel movements (7/wk) (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.40-0.80). Those reporting hard stools also had reduced odds (OR, 0.75; 95% CI, 0.55-1.02). There was no association between diverticulosis and straining (OR, 0.85; 95% CI, 0.59-1.22) or incomplete bowel movement (OR, 0.85; 95% CI, 0.61-1.20). We found no association between dietary fiber intake and diverticulosis (OR, 0.96; 95% CI, 0.71-1.30) in comparing the highest quartile with the lowest (mean intake, 25 vs 8 g/day).

In our cross-sectional, colonoscopy-based study, neither constipation nor a low-fiber diet was associated with an increased risk of diverticulosis.