Obesity, inactivity tied to common colon disease

NEW YORK (Reuters Health) - Women who don't exercise or who are overweight are slightly more likely to be hospitalized for a common disorder of the large intestine called diverticular disease.

The findings, reported by a Swedish research group, come from the largest study yet to look at the relationship between lifestyle, weight and the intestinal abnormality, in which bulging pouches form in the lining of the colon.

"Since the early seventies, the only risk factor for diverticular disease that has been discussed is (the lack of) dietary fiber, but now we have understood that there are other significant contributors to the development of disease," Dr. Fredrik Hjern, the lead author of the study, wrote in an email to Reuters Health.

Hjern and his colleagues at the Karolinska Institute in Stockholm gathered data from nearly 40,000 women who participated in a health survey in 1997.

The questions asked about exercise, diet, smoking, time spent watching TV and reading, and other lifestyle and health history details. Researchers also measured the body mass index (BMI) of each woman, a measure of weight relative to height.

Through 2009, the researchers tracked which women were hospitalized for diverticular disease.

Though more than half of people over age 60 have some form of diverticular disease, not all people have symptoms, which can range from mild discomfort to bleeding, tears and extreme pain.

Among the 40,000 women in the Swedish study, 628 were admitted to the hospital because of diverticular disease, and 98 of them had a perforation or pus-filled mass in the colon.

Compared to women who had a normal BMI, which is considered 20 to 25, overweight women with a BMI of 25 to 30 were 29 percent more likely to be hospitalized for diverticular disease.

Obese women, whose BMI was over 30, were 33 percent more likely to be hospitalized.

Similarly, exercising less than 30 minutes a day was tied to an increased risk of going to the hospital compared to women who worked out frequently.

But even with those extra risk factors, hospitalizations for diverticular disease remain rare -- amounting to only 2.2 percent of the obese women, for instance.

The authors estimated that each year, 140 out of 100,000 women are admitted to the hospital because of a flare-up. A 30-percent increase would mean that 182 out of 100,000 women would go to the hospital.

The new study, in the American Journal of Gastroenterology, does not prove that being heavy or inactive causes diverticular disease. And Hjern said he doesn't know how to account for the link.

One possibility is that being overweight could stimulate inflammation and damage the large intestine. Another speculation is that the beneficial bacteria in the gut might be different between obese and normal weight women.

As for the link between exercise and a lower risk of diverticular hospitalizations, that too is unknown, but could perhaps have something to do with pressure on the colon or hormonal changes among those who exercise, Hjern said.

For many cases, diverticular disease is managed by increasing fiber in patients' diets. In the most extreme flare-ups, patients can undergo surgery to remove the damaged part of the colon.

According to Hjern, patients could also lose weight and exercise to try and prevent symptoms.

SOURCE: bit.ly/vtzxTe, The American Journal of Gastroenterology, online October 18, 2011.