Meats differ in effect on colon cancer risk

People who eat a lot of processed meats may have a higher risk of developing pre-cancerous growths - polyps - in the colon, while the opposite may be true for fans of chicken, a new study suggests.

Researchers found that among 1,520 adults with a history of colon polyps, those who ate a diet heavy in processed meats had a higher risk of polyp recurrence than those with the lowest intake. On the other hand, patients who favored chicken had a lesser risk of new polyps than those who ate the least.

Colon polyps are growths that, while usually benign, can become cancerous. Patients in the current study had all had polyps removed and were then followed for 4 years to detect any recurrences.

Overall, the one-quarter of patients with the highest intake of processed meat were 75 percent more likely to develop an advanced polyp compared with the one-quarter of patients who ate the least processed meat, the researchers found.

In contrast, those with the highest chicken intake were 39 percent less likely than those who ate the least to develop an advanced polyp.

"Our data indicate that intake of specific meats may have different effects on risk," the study authors state in the American Journal of Gastroenterology.

Dr. Douglas J. Robertson of the VA Medical Center in White River Junction, Vermont, led the study.

A number of studies have linked heavy consumption of red or processed meats to a higher risk of colon cancer, while diets high in fiber from fruits, vegetables and whole grains have been tied to a lower risk of the disease.

But not all studies have found these relationships. And in the current study, high fiber intake was not clearly tied to the overall risk of polyp recurrence.

Patients who ate the most fruit, vegetables and whole grains were, however, less likely to develop polyps in the upper part of the colon. Red meat, meanwhile, was not linked to polyp risk.

Despite that latter finding, the overall results are in line with advice to eat red and processed meats sparingly, Robertson and his colleagues write.

In theory, they note, processed meats could contribute to the development of colon cancer because processing may increase levels of potentially cancer-promoting substances called N-nitroso compounds.

SOURCE: American Journal of Gastroenterology, December 2005.