Obesity raises risks of serious gastrointestinal diseases

The prevalence of obesity and overweight in the United States coupled by the increased risk of gastrointestinal diseases related to obesity raises serious implications for the health of Americans. Several scientific studies in the August issue of The American Journal of Gastroenterology examine the association between obesity and the risk of colorectal cancer and gastroesophageal reflux disease, or GERD.

Dr. Frank K. Friedenberg and colleagues from Temple University School of Medicine in Philadelphia provide an extensive overview of scientific research on the epidemiologic and pathophysiologic associations between obesity and GERD.

Several studies featured in the article highlight the correlation between increasing body mass index (BMI) and the frequency and severity of acid reflux symptoms. One particular study found that accumulation of abdominal fat, as measured by the waist-to-hip ratio, may be the most important risk factor for the development of acid reflux and related complications such as Barrett's esophagus and esophageal adenocarcinoma.

The authors also examined data on the effects of weight loss through diet or surgical methods on acid reflux disease. Several studies suggest weight loss through caloric restriction was beneficial in reducing GERD symptoms. When the authors compared the different surgical approaches for weight loss, a surgical technique called "Roux-en-Y" gastric bypass appeared to be the best method, and was most consistently associated with improvement in the symptoms and findings of GERD. "The mechanism of action through which this surgery is successful at improving GERD may be independent of weight loss and needs further examination," said Dr. Friedenberg.

Researchers at the University of Tokyo and Kameda General Hospital in Japan examined the effect of body weight on the incidence of colorectal adenoma in 7,963 Japanese patients who underwent colonoscopy between 1991 and 2003. Patients who had a family history of colorectal cancer, colorectal polyps, inflammatory bowel disease, colorectal surgery or who took NSAIDS were excluded from the study.

In this cross-sectional study, patients were classified into four groups according to their body mass index (BMI). Researchers found 20.7 percent of patients had at least one colorectal adenoma. Importantly, as the BMI increased, so did the prevalence of colorectal adenomas.

In a separate cohort analysis, 2,568 patients from the initial study underwent a second colonoscopy after one year to compare the effect of body weight changes on the development of new colorectal adenomas. The incidence rates of colorectal adenoma were 9.3 percent in patients who lost 5 percent or more in body weight; 16.2 percent in patients who gained 5 percent or more in body weight; and 17.1 percent in patients who neither gained nor lost weight.

Weight loss was associated with lowered incidence of adenoma, independent of gender, age, initial colonoscopic findings, and initial BMI. Based on their findings, the authors suggest that controlling body weight may decrease the risk of developing colorectal adenomas.

According to ACG President Amy E. Foxx-Orenstein, D.O., FACG, "The magnitude of the obesity epidemic adds a staggering burden to our current health care system. These studies point to the serious potential risks of GI disease for individuals who are overweight or obese."