Colorectal cancer: getting to the bottom of bowel cancer
A large body of evidence suggests a diet high in red and processed meat can increase your risk of developing bowel cancer.
Colorectal (large bowel) cancer is the second most common cancer in England and the third most common cause of cancer death in men after lung and prostate cancer, and lung and breast cancer in women. Between 1971 and 2009, the incidence of colorectal cancer increased by 33 per cent for men and 14 per cent for women. As with breast and prostate cancers, the rates of colorectal cancers vary wildly across the world. For example, rates are high in the UK and USA but almost non-existent in Bangladesh. Migrant studies have shown that as people move from a low-cancer risk area to a high risk area, they develop the same risk of getting colorectal cancer as their host country within two generations. In other words, in most cases this is not an inherited ‘genetic’ disease. It is now well established that causes of colorectal cancer include obesity, alcohol, smoking and poor diet.
Beware meat and dairy
Even the NHS, which is not particularly progressive regarding dietary advice!, says: “A large body of evidence suggests a diet high in red and processed meat can increase your risk of developing bowel cancer.” (NHS, 2014.) In November 2007, The World Cancer Research Fund launched the report Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. It was the most comprehensive report to date published on the link between cancer and lifestyle (WCRF/AICR, 2007). The report warned that eating 150 grams of processed meat a day (the equivalent of two sausages and three rashers of bacon) increases bowel cancer risk by 63 per cent and that 50 grams a day (one sausage) increases the risk by about 20 per cent. Red and processed meat may cause colorectal cancer because the type of iron they contain – haem iron, mainly from the animal’s blood – can cause changes in cells that lead to cancer (Bastide et al, 2011). Other nasties found in red and processed meats are N-nitroso compounds, heterocyclic amines and polycyclic aromatic hydrocarbons, which may directly mutate cells in the large bowel, leading to cancer (Butler, 2014). The iron found in plant foods is non-haem iron, which does not have the same detrimental effects as haem iron. As with breast and prostate cancers, there are mounting concerns that consuming cows’ milk and dairy products raises levels of the growth hormone, IGF-1 in our blood – and we know that higher IGF- 1 levels may cause colorectal cancer. In fact, Professor Campbell states: “insulin-like growth factor-1 is turning out to be a predictor of cancer just as cholesterol is a predictor for heart disease.” In a healthy person, IGF-1 efficiently manages the birth and removal of cells. However, under unhealthy conditions, IGF-1 more vigorously increases the birth and growth of new cells while stopping the removal of old cells, both of which favour the development of cancer (Campbell et al, 2005).