Possible mechanism for the link between red meat and bowel cancer
31 January 2006
Researchers at the Medical Research Council (MRC) Dunn Human Nutrition Unit in Cambridge and the Open University Department of Chemistry in Milton Keynes have observed a mechanism which may explain why eating red meat is linked to an increased risk of bowel cancer. The research is published this week in the journal Cancer Research.
Last year a team at the Dunn unit, led by Professor Sheila Bingham, published epidemiological evidence that red and processed meat are associated with increased risk of bowel cancer. They found that the chance of developing the disease is a third higher for people who regularly eat more than two portions per day of this type of meat compared with those who eat less than one portion per week. The risk is also higher for individuals who consume low amounts of fibre.
This latest research, however, looked for a biological correlation or physiological changes which could explain the epidemiological results. According to the lead investigator Sheila Bingham, “It was difficult due to the inaccessibility of the large bowel and the fact that there are no blood-borne risk markers in bowel cancer. So in this study we obtained cells from the lining of the colon in healthy volunteers eating different diets. We looked at whether eating red meat alters the DNA of these cells.”
The researchers found that when a red meat diet was compared with a vegetarian diet, levels of DNA damage increased. The DNA damage was specific to substances, called N-nitrosocompounds, which are formed in the large bowel after eating red meat. Some of these compounds may combine with DNA and alter it so that it is more likely to undergo harmful changes or mutations that increase the likelihood of cancer.
Work carried out in Professor David Shuker’s group at the Open University had previously established that N-nitrosocompound derivatives of common amino acids found in meat lead to these very characteristic changes to the structure of DNA. Professor Shuker added, “These combined discoveries have allowed us to link red meat consumption to an increased risk of bowel cancer and may give us some clues about developing a screening test for very early changes related to the disease”.
The Chief Executive of the Medical Research Council, Professor Colin Blakemore, said “Large bowel cancer is the second most common cancer in western countries and nearly one million cases occur each year worldwide. This latest study, together with the compelling epidemiological evidence published last year, is an important step towards understanding, and potentially preventing this common disease.”
For further information, or to request an interview with Professor Sheila Bingham, please contact the MRC press office on 020 7637 6011
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