Almost half of all Americans over the age of 60 develop diverticulosis: small, bulging pouches (diverticula) in the colon. In most cases, these diverticula do not cause any discomfort. However, in perhaps 15% of people with diverticulosis, diverticula may become inflamed or infected. The result is a condition called diverticulitis. Symptoms of diverticulitis include pain, nausea, and sometimes fever.

It is thought that the main cause of diverticulosis is the relatively low-fiber diet consumed in developed countries. Treatment of diverticulitis includes dietary changes, antibiotics, and, sometimes, surgery.

Fiber supplements have shown promise for both preventing and treating diverticulosis and diverticulitis.

Studies suggest (but do not prove) that diets high in fiber and low in total fat and red meat may help prevent diverticular disease.1

Furthermore, high fiber consumption may help prevent diverticulitis from developing in people with diverticulosis.2 However, this has not been proven, and the results of the scant published controlled trialson the topic have been inconsistent.3,4

Common fiber supplements include psyllium, glucomannan, and methylcellulose.

Note: Use of fiber supplements during an active bout of diverticulitis is not advisable, because the colon needs to rest.

Contrary to some reports, there is no evidence that obesity or consumption of caffeine or alcohol increases risk of diverticular disease.5 However, high levels of physical activity may reduce the risk of developing the condition.