We've long heard that too much red meat isn't great for our health. Now, a huge new study confirms that diets high in red meat and processed meat appear to increase our risk of premature death.

The study, published in the Archives of Internal Medicine, involved more than 545,000 people -- ages 50 to 71 -- over a period of 10 years. The study concludes that those who eat diets high in red meat and processed meats appear to have a increased risk of death from all causes, as well as from cancer or heart disease.

But in an interesting twist, white meat appeared to have the opposite effect.

The study found that a higher intake of white meats was linked to a slightly decreased risk for premature death and for cancer death. Heather Chappell, senior manager of cancer control policy at the Canadian Cancer Society, said that may pave the way for new studies.

"This is new information that we haven't seen before -- that a diet that's high in white meat actually had a slight protective effect in cancer deaths," she told CTV News. "It's not clear how that happened or what impact that may have, so I definitely think that warrants further research."

Researchers at the National Cancer Institute in the U.S. looked at how meat intake affected more than 500,000 older adults who were part of the National Institutes of Health-AARP Diet and Health Study.

The study participants, who were between 50 and 71 years old when the study began in 1995, were asked to fill out questionnaires to estimate their intake of white, red and processed meats. They were then followed for 10 years through National Death Index databases.

Red meat was defined as all types of beef and pork and processed meats made with red meat such as sausage and bacon. The category also included all foods containing red meat such as chili, lasagna, and stew.

White meat included chicken, turkey, and fish and included processed meats made from poultry, such as turkey sausage.

The researchers found that the one-fifth of men and women who ate the most red meat had a higher risk for overall premature death, death from heart disease and death from cancer compared to the one-fifth of men and women who ate the least red meat.

They made the same finding among those who ate the most processed meat compared to those who ate the least.

Among men, those who ate the most red meat had a 31 per cent increased risk of dying prematurely. Women who ate the most meat saw their risk of dying early jump by 36 per cent.

Men who ate the most meat also had a 22 per cent higher risk of dying of cancer and a 27 per cent higher risk of dying of heart disease. Women in the highest quintile of meat consumption had a 20 per cent higher risk of dying of cancer and a 50 per cent higher risk of dying of heart disease.

Those who ate the most meat ate about 5 oz. of red meat a day -- roughly the equivalent of a small steak or a large hamburger -- every day. Those who ate the least had less than 1 oz. of red meat per day, or approximately three slices of corned beef.

Interestingly, those who ate the most white meat intake had a slightly lower risk for total death, death from cancer and death from causes other than heart disease or cancer. It's a finding that surprised Heather Chappel of the Canadian Cancer Society.

"We have not seen this information before: white meat had a slight protective effect in cancer deaths. It is not clear how that happened or what impacts that may have, so that warrants further research," she said.

Think in grams, not kilograms

The researchers conclude that 11 per cent of deaths in men and 16 per cent of deaths in women could be prevented if people lowered their red meat intake to the level of those in the study who ate the least.

Lead author Rashmi Sinha of the National Cancer Institute called the increased risk modest, but added nevertheless that the findings support the advice of several health groups to limit red and processed meat intake.

The researchers say there are a number of reasons why diets high in red meat are worrisome. Meat is a major source of saturated fat, which has been linked to breast and colorectal cancer. As well, cancer-causing compounds can be formed during high-temperature cooking of meat.

Dietician Rosie Schwartz says the study reinforces the message that we need to eat less meat.

"I think people are already cutting back on meat because of the economy. This will give them another incentive," she told CTV.

Because there are health benefits to eating some unprocessed red and white meats, there is no need to shift to a vegan or vegetarian diet, concludes Dr. Barry M. Popkin, of the University of North Carolina, in an accompanying editorial.

"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," he writes.

The Canadian Cancer Society recommends that adult Canadians limit their weekly intake of red meat to 500 grams (18 ounces) and to portion sizes that are 85 grams (3 ounces) when cooked -- smaller than a deck of cards.

As a rough guide, 500 grams of cooked red meat is the same as 700 to 750 grams of uncooked meat.

It also recommends saving processed meat for special occasions, such as ham for a holiday dinner or a hot dog at a sporting event.