Medical researchers might need to go back to the drawing board to figure out the causes of diverticulosis, the small pouches that commonly form along the colon wall and are sometimes associated with a painful condition called diverticulitis.
Conventional wisdom has held that low-fiber diets contribute to diverticulosis. That’s partly because the condition began being diagnosed more frequently as American diets began to rely more heavily on processed foods and less on fresh fruits and vegetables. Regions of the world with high-fiber diets seem to have less diverticular disease.
Now medical experts are not so sure about blaming low-fiber diets. A study out of the University of North Carolina concludes that it’s actually high-fiber diets that might contribute to diverticulosis.
The UNC School of Medicine in Chapel Hill gathered data on more than 2,000 people ages 30 to 80 who had undergone an outpatient colonoscopy at UNC Hospitals from 1998 to 2010. Participants were interviewed about their diet, bowel movements and level of physical activity.
The findings:
- A low-fiber diet was not associated with a higher prevalence of asymptomatic diverticulosis.
- Those participants with the lowest fiber intake were 30 percent less likely to develop pouches along the colon than those with the highest fiber intake.
- Those with more than 15 bowel movements per week were 70 percent more likely to develop diverticulosis than those having fewer than seven bowel movements per week.
- No link could be found between diverticulosis and physical inactivity, intake of fat or intake of red meat.
“Despite the significant morbidity and mortality of symptomatic diverticulosis, it looks like we may have been wrong, for decades, about why diverticula actually form,” said Dr. Anne Peery, the study’s lead researcher, a fellow in gastroenterology and hepatology at UNC.
The study appears in the February 2012 issue of the journal Gastroenterology.
“While it is too early to tell patients what to do differently, these results are exciting for researchers,” said Peery in a UNC media release. “Figuring out that we don’t know something gives us the opportunity to look at disease processes in new ways.”
Many Americans have diverticulosis, without necessarily feeling any symptoms. It is characterized by small pouches called diverticula that bulge out through weak spots in the colon.
About 10 percent of Americans older than 40 have diverticulosis, with the number growing to about 50 percent for people older than 60, according to the National Digestive Diseases Information Clearinghouse.
When the diverticula became inflamed or infected, however, that’s diverticulitis, suffered by 10 to 25 percent of those who show diverticulosis, said the NDDIC.
In addition to abdominal pain and tenderness around the left side of the lower abdomen, patients who have developed diverticulitis can exhibit fever, nausea, vomiting, chills, cramping and constipation.
Complications of diverticulitis include perforations in the colon, blockages, abscesses, peritonitis and bleeding.
So over the years, when doctors have prescribed high-fiber diets, they often have had diverticular disease prevention in mind. The prevailing wisdom is that fruits, vegetables and whole grains, consumed with adequate water, help move stool through the colon. If you’re older and frequently constipated, there might be too much pressure on your colon, which could set up conditions for diverticula.
Peery pointed out, however, that the possible link between constipation and diverticula, whether it produces symptoms of diverticular disease or not, has not undergone enough rigorous study over the years.
The UNC media release noted that researchers are considering microorganisms in the gut as playing a role in diverticulosis.
“There are a lot of good reasons to eat a high-fiber diet, and this study doesn’t change that,” Peery told WebMD. “But it may not protect people from developing diverticula.”
Sources:
“Diets high in fiber won’t protect against diverticulosis.” UNC Health Care media release of Jan. 23, 2012. Web. 31 Jan. 2012. http://news.unchealthcare.org/news/2012/january/diets-high-in-fiber-wont-protect-against-diverticulosis
“Diverticulosis and Diverticulitis.” National Digestive Diseases Information Clearinghouse. Web. 31 Jan. 2012. http://digestive.niddk.nih.gov/ddiseases/pubs/diverticulosis/index.aspx
Boyles, Salynn. “Fiber May Not Prevent Diverticular Disease.” WebMD. 31 Jan. 2012. http://www.webmd.com/digestive-disorders/news/20120123/fiber-may-not-prevent-diverticular-disease
Reviewed February 1, 2012
by Michele Blacksberg RN
Edited by Jody Smith