For decades doctors have warned people at risk of developing the painful intestinal condition known as diverticulitis to avoid eating corn, popcorn, nuts and various seeds. But a recent study suggests that these rough foods need not be avoided.

In the Aug. 27 Journal of the American Medical Association, researchers report that men eating these foods regularly are no more likely to develop diverticulitis than men who seldom ate such roughage.

Diverticula are pockets that bubble out from the lining of the colon in about one-third of people over age 60 and in more than two-thirds of those over 85. They are typically painless and go unnoticed unless detected by colonoscopy. But up to 25 percent of these people develop diverticulitis, when the pockets become inflamed and cause sharp pain, cramping, nausea, vomiting and other woes.

People with diverticulitis and those with quiescent diverticula are routinely counseled to get plenty of fiber in their diets. But while nuts, corn, popcorn and seeds are especially fibrous, they are also poorly digested. Many physicians have long assumed that these foods could contribute to the development of diverticulitis by collecting in the pockets and abrading the intestinal walls. In a 1999 survey of doctors, nearly half said people with diverticula and diverticulitis should avoid these foods, says study coauthor Lisa Strate, a gastroenterologist at the University of Washington and Harborview Medical Center in Seattle. Strate did much of the research while at Harvard Medical School and Brigham and Women’s Hospital in Boston.

In the new study, Strate and her colleagues analyzed health data from more than 50,000 men who had filled out questionnaires on their health every two years starting in 1986. None had diverticulitis at the start, but 801 developed it during the 18-year study period. The data showed that men who ate corn, popcorn or nuts at least twice a week were no more likely to develop diverticulitis or intestinal bleeding than men who ate these foods only once a month or less.

The researchers accounted for differences between the groups, such as other dietary differences, age, physical activity, smoking, weight and the use of anti-inflammatory drugs.

While a single study is rarely enough to change clinical practice, these findings raise doubts about avoiding nuts, corn and popcorn, says Strate. “They give evidence to clinicians to reconsider that recommendation” when counseling people who have diverticulitis or even innocuous diverticula, says Strate.

“It was dogma that small seeds and roughage could cause diverticulitis, that they would get into diverticula and plug them,” says gastroenterologist Martin Floch of Yale University. "This paper is terrific [because] it helps to get that out of the common dogma.”

While the precise cause of diverticula formation remains unclear, Floch says, fiber certainly helps to prevent it. "Everybody should be on a high-fiber diet," he says.

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Found in: Body & Brain