Scientists said they may have found a reason
why eating too much red meat increases the risk of colorectal
cancer.
By studying cells from volunteers eating different diets,
they discovered that red meat raises levels of compounds
in the large bowel, which can alter DNA and increase the
likelihood of cancer.
"It is the first definite link between red meat and the
very first stage in cancer," said Professor Sheila Bingham,
of the Medical Research Council Dunn Nutrition Unit in
Cambridge, England.
In earlier research, Bingham and her team showed there
was a strong correlation between eating red and processed
meat and the risk of colon cancer.
The chance of developing colorectal cancer was a third
higher in people who regularly ate more than two portions
of red or processed meat a day compared to someone who
ate less than one portion a week.
In their latest study, published in the journal Cancer
Research, the scientists studied cells from the lining
of the colon from people who consumed red meat, vegetarian,
high red meat or high fibre diets for 15 days.
"We looked at whether eating red meat alters the DNA
of these cells," Bingham stated.
They found that red meat consumption was linked to increased
levels of substances called N-nitrosocompounds, which
are formed in the large bowel. The compounds may stick
to DNA, making it more likely to undergo mutations that
increase the odds of cancer.
The DNA damage may be repaired naturally in the body,
and fibre in the diet may help the process. But if it
isn't, cancer can develop, Bingham said.
The scientists said the findings could help to develop
a screening test for very early changes related to the
disease.
Colorectal is one of the most common cancers in developed
countries. More than 940,000 cases are diagnosed each
year and about 492,000 people die from the illness, according
to the International Agency for Cancer Research (IARC)
in Lyon, France.
A diet rich in fat, animal protein and refined carbohydrates
and lack of exercise are risk factors for the illness.
Most cases are in people over 60 years old and about 5
percent of them are inherited.
Health experts estimate that about 70 percent of colorectal
cancers could be prevented by changes in diet and nutrition.
Diarrhoea, constipation and rectal bleeding can be symptoms.
