Rates of cancer are increasing dramatically as the factors directly related to cancer incidence, including ageing, obesity, and ‘Westernised’ dietary habits, have been increasing during the past several decades. By 2040 the number of new cases of cancer are expected to rise by 63 per cent to 29.5 million. A ‘Western’ lifestyle is often characterised by a diet high in red and processed meat, both of which have been linked to colorectal (bowel) cancer in World Cancer Research Fund’s (WCRF) latest expert report.
Cancer is one of the leading causes of death worldwide – around one in six deaths are due to cancer. Yet around 40 per cent of cancer cases are preventable, equating to nearly 144,000 cases a year in the UK and 694,000 cases in the US. WCRF’s latest expert report, Diet, Nutrition, Physical Activity and Cancer: a Global Perspective, is the result of an ongoing review of decades of evidence by world-renowned, independent experts from across the globe. This report showed strong evidence that eating red or processed meat increases the risk of colorectal cancer.
Meat is a valuable source of nutrients, including protein, iron, zinc and vitamin B12. However, eating meat is not an essential part of a healthy diet as consumption of red meat specifically is not essential to meet adequate nutritional guidelines. Plant sources, such as pulses and grains, can provide sufficient quantities of protein and other key micronutrients. WCRF recommend that if people do eat red meat, they should limit consumption to no more than 350-500 grams of cooked weight per week (that’s about three portions). This amount identifies the level of consumption that is judged to provide a balance between the advantages and the disadvantages of consuming red meat. It is important to note, however, that simply removing meat from a diet without consideration of the overall balance of the diet may compromise its nutritional adequacy, especially in typical ‘Western-type’ diets. Processed meat is any meat that has been smoked, cured or had salt or chemical preservatives added, such as salami and chorizo. Our recommendation is to eat very little, if any, processed meat.
Colorectal cancer is the third most common cancer worldwide with 1.8 million new cases recorded globally in 2018, accounting for ten per cent of all new cases of cancer. Furthermore, it is the fourth most common cause of death from cancer, estimated to be responsible for over 800,000 cancer deaths. Limiting the amount of red and processed meat we eat is important for lowering risk of this common cancer.
A number of mechanisms have been investigated to explain why eating red and processed meat increases the risk of colorectal cancer. Cooking red meats at high temperatures can result in the formation of substances which have been linked to colorectal cancer development in experimental studies. In addition, haem iron, which is present at high levels in red meat, has been shown to promote the development of colorectal tumours. Processed meats are often cooked at high temperatures, which can lead to increased exposure to polycyclic aromatic hydrocarbons which are formed when organic substances like meat are burned, and may also have the potential to be cancer causing.
Overall it is likely that a combination of these mechanisms contributes to the higher risk of colorectal cancer among people consuming high quantities of red or processed meat.
The findings of WCRF’s expert report were used to develop ten Cancer Prevention Recommendations. These recommendations work together as an overall way of living healthily to prevent cancer and are based on evidence that has now proved consistent for decades. Plus, a growing number of independent studies shows that the more closely you follow these recommendations, the lower your risk of developing cancer.
This article was written by Susannah Brown, Acting Head of Research Evidence and Interpretation at WCRF for Eating Better.
Find out more about how to reduce your risk of cancer in WCRF’s Third Expert Report.