= Full article availableA major new American Cancer Society study serves up another reason to watch your consumption of red meat: Too much red meat significantly raises your risk of colorectal cancer.
The study of nearly 150,000 Americans, the largest and most comprehensive to date, was published in the Journal of the American Medical Association. The findings also linked colorectal cancer risk and prolonged high consumption of processed meat.
“More than two dozen studies have already examined the relationship between consumption of red or processed meat and increased risk of colorectal cancer, with most showing greater risk in people with higher consumption,” says Michael J. Thun, MD, the society’s chief of epidemiology and a co-author of the study. “Those studies along with this new one make it clear there is credible evidence that high meat consumption increases the risk of colon cancer.”
Prolonged high consumption of red meat was described as at least three ounces daily for men—about the amount in one large fast-food hamburger—and two ounces daily for women over a period of 10 years. For processed meat, it meant at least one ounce per day—equivalent to a piece of bologna or four slices of cooked bacon—five to six days per week for men and two to three days per week for women.
For the study, 148,610 adults ages 50 to 74 reported on their meat consumption at 10-year intervals while enrolled in the society’s Cancer Prevention Study II (CPS II) Nutrition Cohort. Meat consumption ranged widely, with a 10-fold difference between the lowest and highest quintiles of red meat consumption in men and a 17-fold difference in women. On average, men consumed more red and processed meat than women—2.1 ounces a day of red meat and 0.5 of processed meat for men compared to 1.4 ounces of red meat per day and 0.2 of processed meat for women.
The study found the biggest meat eaters in both questionnaires, 10 years apart, were 30 percent more likely to develop lower colon cancer than those who ate little or no red meat. Those who ate the most processed meat were 50 percent more likely to develop lower colon cancer. That increased colorectal cancer risk is similar to or somewhat smaller than the risks associated with other lifestyle factors, such as physical inactivity and obesity.
Researchers didn’t attempt to address how red and processed meat might promote cancer. Previous studies have pointed to possible culprits including iron in red meat, carcinogens produced by cooking at high temperatures, fat in meat and/or salt or nitrates/nitrites in processed meat.
If you switch more of your meals from red and processed meat to poultry and fish, the study found a potential double benefit: Besides reducing one risk factor, researchers also found a “marginally significant” link between lower risk of colorectal cancer and long-term consumption of poultry and fish.
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