In Canada, the average person eats 200 grams of meat a day, or the equivalent of two quarter-pound hamburgers. (CBC)

People over 50 who eat large amounts of red and processed meats face a higher risk of death from heart disease and cancer than those who eat the smallest amounts of hamburgers and hot dogs, a study of more than 500,000 Americans reports.

In Monday's issue of the Archives of Internal Medicine, Rashmi Sinha and colleagues at the National Cancer Institute in Rockville, Md., looked at the link over 10 years between meat intake and risk of death among people aged 50 to 71.

Those in the top fifth for eating red meat — at a median of 62.5 grams per 1,000 calories per day or a quarter-pound hamburger daily — had a higher risk of death overall, death from heart disease and death from cancer than those in the bottom fifth.

Those in the lowest group ate a median of 9.8 grams per 1,000 calories per day or the equivalent of a hamburger per week.

During the 10-year follow-up period, 47,976 men and 23,276 women died.

"For overall mortality, 11 per cent of deaths in men and 16 per cent of deaths in women could be prevented if people decreased their red meat consumption to the level of intake" in the lowest quintile or one-fifth, the study's authors wrote.

"The impact on cardiovascular disease mortality was an 11 per cent decrease in men and a 21 per cent decrease in women if the red meat consumption was decreased to the amount consumed by individuals in the first quintile."

Limit intake

The increased risk was deemed modest by the researchers, but they said the findings support the advice given by several health groups to limit intake of red and processed meat to decrease cancer incidence.

The increased risk from eating the most processed meat was slightly lower overall than for red meat.

And people who ate more white meat such as chicken and fish had a slightly lower risk for death over the course of the study compared with those in the bottom one-fifth for white meat consumption.

The researchers proposed several possibilities for why red meat may be associated with death:

• Cancer-causing compounds are formed during high-temperature cooking of meat.
• Meat is a major source of saturated fat that has been linked with breast and colorectal cancer.
• Lower meat intake has been linked to a reduction in heart disease risk factors, including lower blood pressure and cholesterol levels.

Participants were drawn from a group of people over 50 that is healthier on average than similarly aged Americans, so the findings may not apply to other groups, the researchers cautioned.

The team took into account risk factors such as smoking, family history of cancer and high body mass index, but relied on people to recall what they ate, which is prone to error.

Dietary shift

Reducing the amount of meat consumed would not only improve health but also the environment, Barry Popkin, director of the Interdisciplinary Obesity Center at the University of North Carolina at Chapel Hill, said in an accompanying editorial.

Livestock increase greenhouse gas emissions, contributing to global climate change, and farm subsidies distort prices to encourage meat-based diets, said Popkin, noting he is not a vegetarian.

Since eating some red and white meats carries health benefits, the consensus is not for a full shift to vegan or vegetarian diets, he argued.

"Rather, the need is for a major reduction in total meat intake, an even larger reduction in processed meat and other highly processed and salted animal source food products and a reduction in total saturated fat," Popkin wrote.

For nutritionist Melissa Putt of Toronto, there's no point demonizing food categories.

"We can't be putting food, or red meat, into a bad food category, because that's just not what it is," said Putt.

"We have to look at food trends and how our food intake is changing. It's certainly not changing on the saturated fat front."

The study also focused on extremes of meat consumption rather than what most Americans eat, said Ceci Snyder, a dietician for the National Pork Board.

The National Cattlemen's Beef Association said lean meat can be part of a balanced diet.

With files from the Associated Press