Colorectal cancer, most commonly referred to as colon cancer, accounts for 639 000 deaths worldwide every year. Colon cancer is the third most common cancer worldwide and the second leading cause of cancer deaths in the United States.

The risk of colon cancer begins to increase after the age of 40 and rises sharply at the ages of 50 to 55; the risk doubles with each succeeding decade and continues to rise exponentially. Colon cancer is one of the two major cancers (the other being stomach cancer), the risk of which is commonly agreed to be modified mainly by food, nutrition and lifestyle habits.

Research is convincing that eating too much red and processed meat increases risk of colon cancer. A large population study now suggests that how you cook your meat, white and red meat, is also important. The European study linked increased risk of pre-cancerous growths in the colon to cancer causing compounds that form when meat is grilled or fried at high temperatures.

This study questioned more than 25,000 adults about details of their diets, including what and how much red meat and poultry they ate and how it was cooked. Based on this, researchers estimated levels of three major heterocyclic amine (HCA) compounds typically consumed. HCAs form when long or intense heat reacts with animal muscle, both red and white meat, as well as fish. These compounds can damage our DNA and begin the development of cancer.

As in past studies, people who ate more red and processed meat were more likely to develop colorectal adenomas (benign tumors that can transform into cancerous ones and are the source of most colon cancer). Consumption of all three of the major HCAs was also higher among those who developed adenomas. Looking only at the left section of the colon that seems most vulnerable to meat-associated risks, those with greatest consumption of the most abundant HCA were 59 percent more likely to develop adenomas than those who consumed the least.

Laboratory and smaller human studies have studied HCAs’ impact on cancer risk for years, but this European study was only the second large population study examining the issue. Previously, a major U.S. study examined more than 14,000 men to see how HCA consumption was linked to adenoma in that left section of the colon most sensitive to meat’s impact.

The U.S. researchers suggested that looking at total HCA consumption may provide an unclear picture because that total figure could include varied proportions of HCAs that are more or less damaging. Besides, colon cancer and adenoma risk may relate not only to HCAs, but also to other damaging compounds formed in cooking. A total cell-damaging score (created by methods from previous research) was more strongly linked to left colon adenoma risk than any individual HCA, though even here the link was not strong. Consumption of processed meat presented the strongest association. Yet consumption of total cell-damaging compounds seemed to be a separate influence, even after accounting for processed meat intake.

Together, these and other studies tell us that although a primary step to lower risk of colon cancer is limiting red and processed meat, the issue of how our meat, poultry and fish is cooked is also important. The HCAs and other cell-damaging compounds that form when meats are cooked with high temperature grilling and frying, especially when well-done or extremely browned, are not carcinogenic on their own. Proteins in our body must activate them and activation depends upon both diet and genetics. The effect we see in studies is likely an average of individuals who are strongly and not strongly affected.

The bottom line for consumers is to watch what you eat and how it’s cooked. Avoid frying and if grilling, reduce the temperature and don’t char food. A mostly plant-based diet plays an important protective role: less meat automatically means less of meat’s cell-damaging compounds and more plant foods mean more of the protective compounds that inactivate the damaging ones.