Live longer by reducing red meat intake: Study
By Sharon Kirkey, Canwest News Service
Eating large amounts of red or processed meat increases the risk of dying, new research involving more than half a million people shows.
The sheer size and quality of the study has led the Canadian Cancer Society to say it will be lowering its recommended limit on the amount of red and processed meats people should consume.
The group now recommends limiting red meat to 500 grams, or 18 ounces per week, to reduce the risk of cancer.
The new study found men and women who eat about four ounces of red meat per day — the equivalent of a small steak or quarter-pound of meat — had a higher risk for overall death, and dying from heart disease or cancer than those who ate less than one ounce of red meat daily.
"Less than an ounce would be around threes slices of ham," says lead author Rashma Sinha, of the U.S. National Cancer Institute.
High intakes of red meat had already been linked to a greater likelihood of developing colorectal cancer, the second leading cause of cancer death in Canada.
"This takes it that next step and actually looks at the impact that has on cancer deaths," says Heather Chappell, senior manager of cancer control policy at the Canadian Cancer Society.
"This really is a significant addition to our body of knowledge in this area."
The study, published this week in the Archives of Internal Medicine, involved 322,263 men and 223,390 women, aged 50 to 71, recruited from eight American states and cities between 1995 and 2005. Volunteers filled out questionnaires that asked about their usual consumption of food and drinks, including a full range of meats.
Red meat included bacon, beef, cold cuts, ham, hamburger, hot dogs, liver, pork, sausage, steak and meats in foods such as pizza, chili lasagna and stew.
White meat included chicken, turkey and fish, as well as poultry cold cuts, canned tuna and low-fat sausages and hot dogs made from poultry.
Processed meat included bacon, red meat sausage, cold cuts, ham and regular hot dogs.
Next, people were grouped into five categories, based on their meat intake. Researchers compared the highest with the lowest meat eaters.
About 48,000 men, and 23,000 women died during the follow-up period.
Overall, "we found that the consumption of red and processed meat was associated with a modest increase in total mortality, cancer mortality and cardiovascular mortality in both men and women," Sinha says.
In contrast, those with the highest white meat intake had a slightly lower risk for death from any cause, and death from cancer.
A typical serving of meat is three to four ounces. Heavy red meat eaters consumed about 8 1/2 servings of meat per week, compared to low-end meat eaters who consumed just over one serving per week.
Men who ate the most red meat had a 31 per cent increased risk of overall death during the study compared to the one-fifth of males who ate the least amount. For women, heavy red meat eaters had a 36 per cent higher risk of dying. The findings held after researchers took family history, smoking, body mass and other risk factors into account.
"For overall mortality, 11 per cent of deaths in men and 16 per cent of deaths in women could be prevented" if people had consumed red meat at the lowest level of intake, the researchers write.
Among men, heavy red meat eaters had a 22 per cent increased risk of dying from cancer, and a 27 per cent higher risk of death from cardiovascular disease over the study period. For women, the risk of dying from cancer increased 20 per cent, and about 50 per cent for death from heart disease.
Other studies have looked at meat and mortality, but they were done mainly on Seventh-day Adventists in the U.S. and other vegetarian populations in Europe.
"They combined their results, so it was a bit more ambiguous. This is a big study. That's what's interesting," Sinha says.
She cautioned the risk has to be put into perspective. Smoking, for example, remains the No. 1 preventable cause of cancer.
"This is not a definitive study on whether or not Americans should eat red meat," says Sinha, senior investigator in the Nutritional Epidemiology Branch of the Division of Cancer Epidemiology and Genetics.
But the study comes amid rising rates of obesity, heart disease and cancer, and a "rapid shift" toward more consumption of all animal source foods, Barry Popkin, of the University of North Carolina, Chapel Hill, says in an accompanying editorial.
It's not clear what it is about red meat that may increase the risk of death. It could be the compounds produced during high-temperature cooking, or the preservatives in meat. Saturated fat in meats can raise cholesterol and blood pressure, and the more meat people eat, the less they may consume of other foods such as grains, fruits or vegetables.
But the biggest meat eaters in the study were also more likely to be "out of shape and overweight," says Toronto cardiologist Dr. Beth Abramson, a spokesperson for the Heart and Stroke Foundation.
It's hard to tease out if it's the actual food, or the lifestyle it's associated with, she says. Still, she says, "there is a scientific rational to be eating lower fat in general."
The Heart and Stroke Foundation recommends selecting lean meat and alternatives, trimming visible fat from meats, removing skin from poultry and using cooking methods such as roasting, baking or poaching that require little or no added fat.