Diverticula are bulging, sac-like pouches in the wall of the colon that protrude outward from the wall of the colon. Diverticula appear most often in individuals over 40 whose diet is low in fiber. In diverticulosis the pouches are present but the individuals do not have any symptoms or discomfort. In diverticulitis, the diverticula are inflamed and often infected when undigested food and bacteria are caught in the diverticula. Patients experience pain, either constipation or increased frequency of defecation, nausea, vomiting, and low-grade fever. In severe cases, surgical removal of the infected area of the colon is necessary. Changing to a high-fiber diet usually relieves the symptoms.