Diverticulitis is a condition in which abnormal pouches (diverticula) that form in the colon become inflamed. While the causes are currently unproven, many healthcare providers believe it is linked to a low-fiber diet. The condition is common in industrialized countries like the United States, England, and Austrialia (where low-fiber diets are common), but rare in countries of Asia and Africa (where people eat high-fiber vegetable diets).