The condition of having diverticula is called diverticulosis. About half of all Americans age 60 to 80, and almost everyone over age 80, have diverticulosis. When the pouches become infected or inflamed, the condition is called diverticulitis. This happens in 10 to 25 percent of people with diverticulosis. Diverticulosis and diverticulitis are also called diverticular disease .
Doctors believe a low-fiber diet is the main cause of diverticular disease.
The disease was first noticed in the United States in the early 1900's. At about the same time, processed foods were introduced to the American diet. Many processed foods contain refined, low-fiber flour. Unlike whole-wheat flour, refined flour has no wheat bran. The disease is rare in countries of Asia and Africa, where people eat high-fiber vegetable diets.