Each additional daily serving of whole fruits lowered the risk by 5 percent, and women who consumed nearly 10 grams of cereal fiber each day were 10 percent less likely to develop diverticulitis than those who ate the least, about 3 grams. A half-cup of Kellogg’s All-Bran cereal, for example, has a whopping 10 grams of fiber, whereas three-fourths cup of cooked oatmeal has only 3 grams, and a cup of Cheerios, Mr. Valenti’s favorite, also has 3 grams of fiber.
In the Nurses’ Health Study, insoluble fiber, such as that found in bran cereal, was more protective than soluble fiber in foods like black beans. Avocados, sweet potatoes and broccoli are good sources of both kinds of fiber.
In an earlier study among nearly 44,000 male health professionals, fiber from fruit and vegetables, but not cereal, was linked to a reduced risk of diverticular disease.
Mr. Valenti, who admitted that “I don’t eat as much fruit as I should,” said he now knows he must do better if he wants to remain healthy.
Meanwhile, his wife, Linda Brewer, who also hopes to head off yet another attack and who recently learned she had borderline diabetes, has adapted the couple’s at-home menu to include plenty of fiber-rich whole grains and more salads, vegetables and legumes. White rice, white pasta and white bread are no longer served and rarely eaten.
Low-fiber diets reduce the volume and water content of the stool. This predisposes to constipation that in turn increases pressure within the colon that can weaken the muscles of the colonic wall, resulting in a herniation, or diverticular pouch.
An imbalance in the bacterial population of the colon may account for the influence of dietary fiber on the risk of chronic inflammation in the colon even without the development of diverticulitis, researchers at Yale University School of Medicine suggested. They reported in Therapeutic Advances in Gastroenterology in 2013 that a low-fiber diet changes the composition of bacteria in the colon, resulting in a significant increase in anaerobic microorganisms. They suggested that probiotics may help to restore a healthier population of bacteria in the gut.