Epidemiological studies have linked consumption of red meat with increased risk of bowel or colon cancer. A new study found evidence indicating that red meat intake increases DNA damages in the lining of the bowel cells.

The study, published in the Feb. 1 issue of the journal Cancer Research, found consumption of red meat such as beef, lamb, pork and veal, increases the endogenous formation of N-nitroso compounds (NOC), which react with DNA forming NOC-specific DNA adduct, O6-carboxymethyl guanine (O6CMG).

DNA adducts, if not repaired, could lead to the formation of cancer.

In the study, Sheila A. Bingham and colleagues from Wellcome Trust/Medical Research Counsel, Pollok and Pool Ltd, and the Open University assigned three diets: high (420 grams) red meat, vegetarian, and high red meat, high-fiber diets to volunteers for 15 days in a randomized crossover design while they stayed in a volunteer suite where the diets were controlled and all specimens were collected for analysis.

In 21 volunteers, the analysis of apparent total NOC (ATNC) in feces showed the red meat diet resulted in endogenous formation of more NOC than the vegetarian diet.

In colonic exfoliated cells, higher levels of the NOC-specific DNA adduct, O6CMG was found in those on the high red meat diet.

Intermediate levels were found in 13 volunteers on the high-fiber, high red meat diet, meaning that a high fiber diet may reduce the effect of high red meat intake.

The results showed fecal ATNC was positively related with the percentage of cells staining positive for O6CM, indicating the fecal ATNC may be used for evaluation of colon cancer risk.

In studies of rats, O6CMG was found in the small intestine when the rats were treated with N-nitrosopeptides. Similar results were found in HT-29 cells treated with diazoacetate. This indicates cancer-causing agents can damage DNA in the small intestine.

The study showed fecal NOC resulting from red meat consumption include direct acting diazopeptides or N-nitrosopeptides, which are able to form alkylating DNA adducts in the colon.

"As the O6CMG adducts are not repaired, and if other related adducts are formed and not repaired, this may explain the association of red meat with colorectal cancer," the researchers concluded in their report.

Eating red and processed meat may increase the risk of developing bowel or colon cancer while eating fish may reduce the risk, according to a previous Bingham’s study published in the June 14, 2005 issue of the Journal of the National Cancer Institute.

The study followed 478,040 men/women aged 25 to 70 from ten European countries including Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden and the UK for an average of 4.8 years.

People who ate more than two servings or 160 g per day of red and/or processed meat are 35 percent more likely to develop bowel or colon cancer compared with those who did not eat or eat less than 20 g per day of red and or processed meat.

Poultry had no effect on the bowel or colon cancer risk while eating fish reduced the risk.

In the study, red meat was defined as beef, lamb, pork and veal. Processed meat referred to meat products consisting of mostly pork and beef such as ham, bacon, sausages, liver pate, salami, tinned meat, luncheon meat and corned beef.

Other than red and processed meat, risk factors for colon cancer include obesity and lack of physical activity, smoking, and excess alcohol. These risk factors were taken into account in the study.

Experts believe more than 70 percent of bowel or colon cancer cases can be prevented by using adequate diets.

Cancer Research UK recommends a healthy diet rich in fruit, vegetables and fiber and low in red and processed meat and fats to reduce the risk of developing bowel cancer.

In the U.S., nearly 100,000 new cases of colon cancer are expected each year and nearly 50,000 die from the disease, according to the American Cancer Society. _