An American study linking high amounts of red and processed meat to increased cancer risks has been praised by some and doubted by others.
Heather Chappell of the Canadian Cancer Society praised the epidemiological work that examines cancer risks to humans and their long-term health progress.
“This is a great study because it was done on such a large number of individuals and followed them for a long enough period of time to really study the impact of meat intake and cancer,” she said.
“This is truly reflecting the relationship between red meat intake and cancer deaths,” she said.
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Mary Ann Binnie, nutrition manager with the Canadian Pork Council, pointed out those who participated and eventually developed cancer had a myriad of health risks by being overweight, smoking and not eating enough fruits and vegetables.
“These are known risk factors for chronic disease,” she said.
“There is more here at play and I think this is what is concerning – looking at a high, steady consumption of meat twice what Canadians are currently consuming and then making these blanket statements without realizing it is a whole lifestyle that you have to look at.”
The study from the U.S. National Cancer Institute surveyed 545,000 people from six states from a list compiled from the American Association of Retired Persons aged 50 to 71 from 1995 to 2005.
Overall, red and processed meat intake was associated with modest increases in total deaths from cancer and cardiovascular disease.
The study found that people in the group that consumed the most red meat, about 4.5 ounces per day or about a quarter pound, had a greater risk of dying than those in the group that ate the least amount, about .11 ounces per day.
Men in the highest red meat intake group had a 31 percent higher risk of dying compared to the lowest intake group. Women had a 50 percent greater risk.
The study’s senior investigator, Rashmi Sinha, told WebMD Health News that 11 percent of all male deaths and 16 percent of female deaths in the study could have been prevented if participants consumed red meat at the same level eaten by people in the lowest intake group.
Deaths due to cancer, cardiovascular disease, injuries, sudden deaths and other diseases were correlated. There were 47,976 male deaths and 23,276 female deaths during 10 years of follow up.
The study asked people to estimate their usual consumption of various foods. Red meat included all types of beef and pork, as well as processed products like bacon, cold cuts, ham, wieners, sausages and meats in pizza, chili or lasagna. White meat included chicken, turkey, tuna and processed poultry products.
People were divided into five groups rating their red and white meat intakes along with other factors like age, family cancer history, alcohol intake, physical activity, smoking, marital status, education, race, body mass index, fruit and vegetable consumption and use of hormone replacement therapy among women.
Comparative information was compiled from vegetarian populations like the Seventh Day Adventists whose main protein sources ares nuts, legumes and grains.
Men and women considered at risk by eating more red and processed meats tended to be married, white, smoked and were overweight. They tended to eat more saturated fat and fewer fruits and vegetables or vitamin supplements and had lower levels of physical activity. The study’s results corrected for those factors.
For white meat, statistics showed an overall decrease in sudden death as well as cancer and cardiovascular death among the top consumption group.
They usually ate more fibre, fruit, and vegetables, did not smoke and managed their weight.
These findings correlate with the American Institute for Cancer Research and World Cancer Research Fund, which recommended lowering red meat intake to minimize the risk of disease, especially colorectal cancer.
“We have known for some time red meat and processed meat increase the risks of developing colorectal cancer,” said Chappell.
Colorectal cancer is the second leading cause of cancer death among Canadians. In 2008, there were about 21,500 cases of colorectal cancer and 8,900 died.
The study should be seen as evidence for moderation by restricting average weekly consumption to three servings of about three ounces each. This is a serving the size of a deck of cards.
“No one is saying eliminate red meat. The more red meat that you eat the more at risk you are but there are certainly nutritional benefits,” Chappell said.
Processed meat is a greater risk than red meat because of high levels of nitrates, nitrites, fat and salt.
“With regards to the processed meat, there is no safe amount to eat so the Canadian Cancer Society recommends people limit such meats to special occasions or very occasionally.”.
Chappell said diet, exercise, smoking and alcohol intake play a greater role in determining health risk factors for most Canadians.
“It is difficult to always put a study result into context, so that is probably where the public would want to rely on a trusted source of information. The Canadian Cancer Society is one example and other health-related organizations like that for other types of disease, who can put that into context what impact that would really have on their health,” said Chappell.
Meanwhile, the American cancer institute released a study at the end of November reporting declines in cancer incidence and death rates among men and women of all racial groups in the United States.
Cancer rates in Canada appear stable but a decline is expected, Chappell said.
As well, an EPIC-Oxford nutrition study published March 11 examined cancer rates among vegetarians and meat eaters. It found no real difference in the incidence of colorectal cancer between the two groups.
It pooled 63,550 people aged 20 to 80 from the national health system in the United Kingdom and followed an assessment program where participants were asked about their diet. Smoking, alcohol consumption, family history and weight were also correlated in the study.
It concluded more research is needed.
“The 2007 report from the World Cancer Research Fund, American Institute for Cancer Research, concluded that the evidence that high intakes of red and processed meat cause colorectal cancer is convincing, but that there was no convincing evidence that high intakes of red or processed meat were causally associated with any other type of cancer.”
