How does eating too much meat increase the risk of cancer?

** Many studies have shown that eating lots of red and processed meat can increase the risk of bowel cancer, and possibly stomach and pancreatic cancer.

** Red meat includes all fresh, minced and frozen beef, pork and lamb. Processed meat includes ham, bacon, salami and sausages. White meat, such as chicken, is unlikely to increase the risk of cancer.

** Scientists think there are a number of ways in which red and processed meat can increase the risk of cancer – they involve the chemicals found in these meats. Some chemicals are a natural part of the meat, and others are made when the meat is preserved or cooked at high temperatures.

** Red and processed meat contains a red pigment called haem. Haem could irritate or damage cells in the bowel or fuel the production of harmful chemicals by bacteria in the gut, which could lead to a higher risk of cancer. Almost all red and processed meats contain greater amounts of haem than white meats. This may partly explain why red and processed meats increase cancer risk while white meats don’t.

** Chemicals called nitrates and nitrites are often used to preserve processed meat. In the bowel nitrites can be converted into cancer-causing chemicals called N-nitroso compounds (NOCs). The presence of these chemicals may explain why many studies have found that processed meat increases the risk of cancer to a greater extent than red meat.

** Cooking meat at high temperatures such as grilling or barbecuing can produce cancer-causing chemicals called heterocyclic amines (HCAs) and polycyclic amines (PCAs).

** The presence of these chemicals may explain why some studies find that meat cooked at high temperatures might increase the risk of bowel cancer to a larger extent than meat cooked at lower temperatures, such as boiling or braising.