Diverticulitis occurs when diverticula in the colon become inflamed or infected, according to WedMD. Diverticula are most common in the lower part of the large intestine, known as the sigmoid colon. These weakened spots in the intestinal wall, ranging from pea-size to larger, form as a result of increased pressure in the colon.
Diverticulosis, as opposed to diverticulitis, is the formation of multiple diverticula and is extremely common, occurring in approximately 10 percent of people past the age of 40. In those over the age of 60, the occurrence rate rises to 50 percent, according to WebMD. Though most people never suffer any ill effects, complications such as diverticulitis do occasionally occur.
Researchers and doctors have not identified a specific cause of diverticulitis but have formed a few theories, according to EverydayHealth.com. One of the most widely accepted theories is that increased pressure in the colon leading to the formation of diverticula may be caused by constipation or other digestive problems. When bacteria and fecal matter present in the colon become lodged in the diverticulum, the result is diverticulitis. For this reason, doctors often advise those with diverticulosis against eating seeds, popcorn or nuts, which could potentially lead to the blockage of diverticula and cause a flare-up of diverticulitis.