A major study has found fresh evidence linking eating red and processed meat and bowel cancer, scientists say.
There are health concerns over red meat
The European Prospective Investigation into Cancer and Nutrition (EPIC) looked at the dietary habits of over 500,000 people across Europe over 10 years.
Bowel cancer risk was a third higher for those who regularly ate over two 80g portions of red or processed meat a day, compared to less than one a week.
EPIC's study is reported in the Journal of the National Cancer Institute.
BOWEL CANCER RISK
There are 17 cases per 10,000 50-year-olds a year among the group eating more than two portions of red meat a day
There are 12 cases per 10,000 50-year-olds a year among the group eating less than one portion of red meat a week
On average, people eat 95g of red meat a day
A sausage for breakfast, a ham sandwich for lunch and a steak in the evening would add up to 205g of meat
Since it began, 1,330 people have developed bowel cancer.
The study also found a low fibre diet increased the risk of bowel cancer.
Eating poultry had no impact but the risk for people who ate one portion or more of fish every other day was nearly a third lower than those who ate fish less than once a week.
Lead researcher Professor Sheila Bingham, of the MRC Dunn Human Nutrition Unit in Cambridge, said: "People have suspected for some time that high levels of red and processed meat increase risk of bowel cancer, but this is one of the largest studies worldwide and the first from Europe of this type to show a strong relationship."
Professor Bingham said there were several theories about why red meat should increase the risk of bowel cancer.
In England and Wales the lifetime risk of being diagnosed with bowel cancer is 1 in 18 for men and 1 in 20 for women
18,500 cases in men and over 16,000 cases in women are newly diagnosed each year
If the cancer is caught at an early stage, eight out of 10 cases can be treated
She believes the most likely explanation is that compounds called haemoglobin and myoglobin, which are found in red meat, trigger a process called nitrosation in the gut, which leads to the formation of carcinogenic compounds.
Alternatively, the problem might be caused by compounds called heterocyclic amines, carcinogenic compounds created in the cooking process.
However, these compounds are also found in poultry, which has not been linked to an increased cancer risk.
Professor Tim Key, of the charity Cancer Research UK, said: "This study strengthens evidence that bowel cancer risk can be cut by increasing fibre in the diet and reducing consumption of red and processed meat."
The researchers defined red meat as beef, lamb, pork and veal.
Processed meat was mostly pork and beef that were preserved by methods other than freezing. They include ham, bacon, sausages, liver pate, salami, tinned meat, luncheon meat and corned beef.
The Meat and Livestock Commission (MLC) said people in Britain ate well below the 160g per day consumption levels that were used to class high intake in the study.
Mike Attenborough, MLC technical director, said: "Once again this points towards the need for moderation and balance in what we eat."
The study was funded by the Medical Research Council, Cancer Research UK and the International Agency for Research on Cancer.
Red meat is a mainstay of my diet and this study won't change my eating habits. There are plenty of other cancers that people can develop and plenty of other ways to die that don't include red meat! The thing that worries me most about this study is the huge amounts of money that went into producing it when it could have been put to better use in the search for cancer cures. It is commonsense that everything in moderation is a good thing!
Steven Buick, Coatbridge, Scotland
Confused more than worried. I eat red meat every day, approximately 70g a day, but I also eat fish several times a week and have a very high fibre diet. So where does that leave me? These findings are generally too black and white.
Ronnie, Stoke, UK
Your report is a bit misleading as when the food constituents were assessed, high intakes of sulphur and sulphate were associated with relapse, which could explain the link with red meat and alcohol, say the authors. The main sources of dietary sulphur are the sulphur amino acids, found in high protein foods, such as red meat, cheese, milk, nuts and eggs, and sulphate. Sulphate is found in brassica vegetables, such as broccoli, and is used as a preservative in processed foods, especially bread, beer, sausages, and dried fruit. Many alcoholic drinks also contain sulphate. So could it be better to cut down on sulphate, not meat per say?
These studies stop short of illuminating causality. In this case, I immediately am led to ask: what's in the meat that increases the risk? Is it the fat per se? Or is it the lipophilic contaminants like dioxins, etc., that concentrate in the fats that underlie the increase in risk - many studies have shown that meats contain higher levels of such toxic compounds. These two different possibilities have profoundly different implications for public policy.
JP Myers, Charlottesville, VA
My father has incurable bowel cancer and my uncle died of it, which puts me in a high risk group. This sort of information should be being distributed by the government, not left for the public to pick out of web sites. Give it a month and the Meat and Livestock Commission will commission a study by its own people who will contradict this. We need to get away from the situation of one body releasing its finding, only to be followed by a vested interest releasing a study which contradicts it. If it weren't for the vested interests lobbying the government, this sort of information would be pinned to everyone's fridges.
Steven Glenister, London, UK
I'm worried about how confusing information relating to health risks is. It seems every morning when I turn on the BBC news I'm hearing about something else I should or shouldn't be eating. Often this is contradictory anyway! Also this new study shows a danger in eating two portions of red meat a day, which to be fair I can't imagine a lot of people do. Perhaps what we should be promoting is a healthy, balanced diet encompassing all the food groups in moderation!
This will make me rethink my children's diet. I never considered the ham in their sandwiches or the sausages and bacon that they eat as likely to be a problem, but over a lifetime it may well be a risk. Its out with the sausages, in with the chicken.
Diane Langford, Farnborough, Hants