If you have diverticulosis, which foods should you eat … and which foods should you avoid? Johns Hopkins experts answer these common questions and offer bottom-line advice.

As we age, most of us develop small pouches (diverticula) that bulge outward through weak points in the wall of the large intestine -- a condition called diverticulosis. The condition is present in about half of Americans ages 60-80 and in virtually everyone older than age 80. A disorder called diverticulitis, an infection or inflammation of diverticula, develops in about 10–25% of people with diverticulosis.

It was once thought that people with diverticulosis should avoid seeds and nuts because they can become lodged in diverticula, the pea-sized pouches in the intestinal wall that characterize this condition, and may often lead to more serious inflammation and infection known as diverticulitis. But it’s now understood that some of the very foods that were once thought inappropriate for diverticulosis may actually be beneficial.

Diverticulosis is strongly associated with a low-fiber diet. Stool formed from refined grains and fatty foods moves slowly through the intestine and leads to constipation. The increased pressure required to keep stool moving can prompt the formation of diverticula. Fiber bulks up the stool, encourages it to move through the intestine, and helps prevent constipation. Therefore, adequate fiber intake of 20-30 g a day may prevent diverticula from developing as well as existing pouches from worsening or progressing from diverticulosis to diverticulitis.

Fruits and vegetables, including ones with small seeds like tomatoes, strawberries, and raspberries, pose no problems for people with diverticulosis and are good sources of fiber, as are whole grains. Be sure to chew foods well. If you need to increase your fiber intake, do so gradually -- a quick increase can cause gas and bloating. You can also use a psyllium-containing bulk-forming laxative (such as Metamucil and others). And be sure to drink about 64 oz of fluid a day.