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High-Fiber Diet: It Doesn't Help, May Worsen, Diverticulosis


In a surprising reversal of what doctors have been telling older patients for 40 years, a new study suggests that eating a high-fiber diet to protect against the intestinal disorder diverticulosis doesn't work.

Diverticulosis, a disease that causes pouches on the wall of the colon (see photo, left), affects about half of Americans by age 60, with two-thirds developing the condition by age 85, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Many suffer only mild symptoms, but about 10 to 25 percent go on to develop diverticulitis, a serious, painful condition that occurs when the pouches become inflamed.

A University of North Carolina study suggests that not only does a high-fiber diet offer no protection against diverticulosis, it can actually worsen the condition.

Among the study's surprising findings:

  • Patients in the study who ate the most fiber had the highest prevalence of diverticulosis, about 30 percent higher than people who consumed the least fiber.
  • Constipation didn't increase the risk of having diverticulosis. In fact, people who had fewer than seven bowel movements a week had a lower prevalence of the disease than those who had movements more frequently.
  • Researchers found no association between diverticulosis and lack of exercise or diets high in fat and red meat.

Based on the study's results, the authors wrote that advice to patients about diverticulosis risk factors and diet recommendations  "should be reconsidered."

The researchers, with UNC's School of Medicine, looked at data from 2,104 patients ages 30 to 80 who had colonoscopies from 1998 to 2010. Patients were interviewed about their diet, bowel movements and level of physical activity.

Lead researcher Anne Peery, M.D., said the study makes it clear that doctors don't really understand why diverticula -- the little pouches on the colon wall --  develop. Although a low-fiber diet has long been thought to play a role, she said there is almost no scientific evidence to back up the association.

"There are a lot of good reasons to eat a high-fiber diet, and this study doesn't change that," she told WebMD, "but it may not protect people from developing diverticula."

In other health news:

Have you done a crossword puzzle today? It can help prevent brain plaque. Brain scans of 65 healthy older adults, average age 76, found that those who did cognitively challenging activities, like crossword puzzles, reading and writing, were a lot less likely to develop brain plaques linked to Alzheimer's disease. The University of California, Berkeley, study found that seniors who had exercised their minds this way the longest had brains comparable to healthy subjects who were 50 years younger.

Move over green tea, three cups daily of black tea may lower blood pressure. Longterm, regular consumption of black tea may help lower blood pressure, an Australian study reports. Study participants, ages 35 to 75, saw blood pressure drop after drinking three cups daily for six months compared to a placebo group. Naturally occurring antioxidants in tea may improve blood circulation.

Swimming also helps lower older adults' blood pressure. Swimming is the second most popular exercise with older Americans after walking and now a University of Texas study suggests that swimming a few times a week can lower blood pressure readings. The study looked at 43 adults, average age 60, with high blood pressure who shaved nine points from their systolic (the top number) reading after three months of swimming three or four times a week.

What makes the biggest difference for diabetics? Regular monthly care. New study shows the huge improvement that regular, frequent healthcare visits make for diabetics: Patients who had monthly primary care counseling on how to improve their health needed less than a month to reach their target goals for blood sugar, blood pressure or cholesterol. Those who received care every six months took more than a year to reach their goals.

Photo: Courtesy Anne Peery, M.D.

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