EVIDENCE-BASED ANSWER: A high-fiber diet may help; available evidence does not support other interventions. A high-fiber diet is often prescribed after recovery from acute diverticulitis, based on extrapolation from epidemiologic data showing an association between low-fiber diets and diverticulosis. No direct evidence establishes a role for fiber in preventing recurrent diverticulitis, however. No evidence supports the common advice to avoid nuts and seeds to prevent diverticulitis. Eating nuts, corn, and popcorn does not increase the risk; in fact, nuts and popcorn may have a protective effect. There is not enough evidence to recommend the anti-inflammatory drug mesalamine or a polybacterial lysate for immunostimulation. Retrospective data do not support routine prophylactic colectomy after 1 or 2 episodes of acute diverticulitis.