September 29, 2011

Red meat cooked at high heat may boost risk of colon polyps

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Vanderbilt researchers are studying the link between colon polyps and a diet heavy in meat cooked at high temperatures.

Red meat cooked at high heat may boost risk of colon polyps

Scientists have already established an association between a diet high in red meat and the risk of colorectal cancer.

Now cancer investigators from Vanderbilt-Ingram Cancer Center and the Veterans Affairs Medical Center (Tennessee Valley Health System in Nashville) have found that eating a steady diet of red or processed meat, especially meat that has been cooked at high temperatures, may increase the risk of developing colon polyps.

Polyps are small growths on the lining of the intestinal tract that may develop into cancer.

The study, led by Wei Zheng, M.D., Ph.D., chief of the Division of Epidemiology and director of the Vanderbilt Epidemiology Center, was published in the journal Cancer Prevention Research.

Patients who were evaluated are enrolled in the Tennessee Colorectal Polyp Study, a colonoscopy-based study group in Nashville. A total of 6,307 participants, ages 40-75, were included in the research, making this the largest study of its kind to date.
Participants had colonoscopies performed at Vanderbilt University Medical Center or the Veterans Affairs Medical Center between February 2003 and March 2010.

All of the patients were interviewed shortly after the colonoscopy and completed a food frequency questionnaire to determine their typical diets, including the amount of red or processed meat they eat on a regular basis. Meats listed on the survey included fast food or home-cooked hamburgers or cheeseburgers, beef steaks, pork chops, ham steaks, bacon, sausage, hot dogs, chicken, fish, gravy from meat drippings, short ribs or spareribs.

Study participants also looked at color photographs depicting how the meat is usually cooked – ranging from rare to extremely well done.

Zhenming (David) Fu, M.D., Ph.D.

Zhenming (David) Fu, M.D., Ph.D.

“We know that well-done meat contains mutagens, such as heterocyclic amines, that have been shown to induce tumors in experimental animals.”

The investigators also evaluated other cancer risk factors among the participants, including tobacco use.

“Overall, current smokers who also were exposed to a high level of red meat or meat-derived mutagens had the highest risk for colorectal polyps,” said Zheng, the study’s senior author.

Previous studies of meat exposure and colon polyps conducted in various parts of the world had produced conflicting results, perhaps because they did not have adequate information about how the meat in the diet was cooked, and thus, these studies were unable to accurately measure meat-derived mutagens, according to Fu.

“The average U.S. diet includes a large amount of red meat, especially meat that is cooked at high temperatures, which may help explain the strong correlation we found between meat intake and risk of colon polyps,” said Fu.

The study was conducted as part of the Specialized Program of Research Excellence (SPORE) in GI cancer, supported by research funds from the National Cancer Institute.

Other contributors to the study included Martha Shrubsole, Ph.D., assistant professor of Medicine, Zhi Chen, M.D., Ph.D., Walter Smalley, M.D., associate professor of Medicine, Preventive Medicine and Surgery, Reid Ness, M.D., assistant professor of Medicine, Yu Shyr, Ph.D., director Vanderbilt Center for Quantitative Sciences, and Huiyun Wu, Ph.D., associate in Biostatistics.