To reduce the risk of bowel cancer, WCRF recommends eating no more than moderate amounts of red meat, and little, if any, processed meat.
What is red meat?
Red meat includes beef, pork, lamb and goat – foods like hamburgers, minced beef, pork chops and roast lamb. We don’t have enough evidence yet about other red-coloured meats, like duck and venison.
What is processed meat?
Processed meat is meat that has been preserved by smoking, curing or salting, or by the addition of preservatives. Examples include ham, bacon and prosciutto, as well as hot dogs and some sausages such at bratwurst and salami. Sausages only count as processed meat if they contain meat that has been preserved with salt or chemical additives.
The evidence for bowel cancer
There is strong evidence that eating red meat or processed meat increases the risk of bowel cancer.1 The analysis of eight cohort studies showed a 17 per cent increased risk per 100g red meat per day. The analysis of nine cohort studies found strong evidence that eating processed meat increases the risk of bowel cancer by 18 per cent per 50g processed meat per day. For both analyses the results of the individual studies were generally consistent – adding strength to the association.
There are several potential reasons to explain how red and processed meat may cause bowel cancer. Red meat contains a compound, haem, which gives it its red colour, and which promotes the formation of potentially carcinogenic N-nitroso compounds in the gut. In addition, when red meat is cooked at high temperatures, this results in the production of compounds (heterocyclic amines and polycyclic aromatic hydrocarbons) that can cause bowel cancer in people with a genetic predisposition. Furthermore, processed red meat has nitrites and nitrates added as preservatives, and these lead to the formations of compounds in the gut that have potential to cause cancer. Processing also changes the nature of the meat, which may play a role in its link to cancer.
What is World Cancer Research Fund’s advice?
Aim to eat no more than about three portions of red meat a week, which is around 350–500g cooked weight (or 525–750g raw weight) a week. Red meat is a good source of valuable nutrients, such as protein, iron, zinc and vitamin B12, so it can contribute to a healthy, balanced diet.
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1WCRF/AICR. Meat, fish & dairy. Meat, fish and dairy products and the risk of cancer. 2018.