Study Finds High Fiber Diets Don't Protect Against Diverticulosis

Posted on March 15, 2012

University of North Carolina researchers are challenging commonly-held beliefs about the causes of diverticulosis, a disease of the large intestine in which pouches develop in the colon wall. A new study of more than 2,000 people found that consuming a diet high in fiber raised, rather than lowered, the risk of developing diverticulosis. The study appears in the February 2012 issue of the journal Gastroenterology. Previously, scientists and physicians have thought that eating a high-fiber diet lowers a person's risk of diverticulosis.

Anne Peery, MD, a fellow in the gastroenterology and hepatology division at UNC and the study's lead researcher, says, "Despite the significant morbidity and mortality of symptomatic diverticulosis, it looks like we may have been wrong, for decades, about why diverticula actually form. While it is too early to tell patients what to do differently, these results are exciting for researchers. Figuring out that we don't know something gives us the opportunity to look at disease processes in new ways."

Diverticulosis affects about one-third of adults over age 60 in the United States. Most cases are asymptomatic, but complications from diverticulosis can be severe, including infections, bleeding, intestinal perforations and even death. An endoscopic picture of a clean colon (large intestine) with diverticula is pictured above.

The UNC study is based on data from 2,104 patients aged 30-80 years who underwent outpatient colonoscopy at UNC Hospitals from 1998-2010. Participants were interviewed about their diet, bowel movements and level of physical activity. The study found those with the lowest fiber intake were 30% less likely to develop diverticula than those with the highest fiber intake. The study also found constipation was not a risk factor and that having more frequent bowel movements actually increased a person's risk. Compared to those with fewer than seven bowel movements per week, individuals with more than 15 bowel movements per week were 70% more likely to develop diverticulosis. The study also found no association between diverticulosis and physical inactivity, intake of fat, or intake of red meat.

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