hot dog with mustard

If you're looking to prevent heart disease and live a longer life, it makes sense to keep red and processed meat to a minimum, according a new study from Northwestern Medicine and Cornell University published today in JAMA Internal Medicine.  

Researchers looked at what nearly 30,000 adults from six long-running studies ate over approximately 19 years (some were followed for as long as three decades) and their rates of heart disease and death. They found that eating even small amounts of meat and poultry increased the risks.

People who ate two servings of processed meat—such as bacon and bologna—each week had a 7 percent higher risk of heart disease than those who ate none. And those who had two weekly servings of red meat had a 3 percent higher risk of heart disease. Eating two weekly servings of both red and processed meat raised the risk of early death from all causes by 3 percent. Two slices of bacon or a hot dog counted as a serving of processed meat and 4 ounces was a serving of red meat or poultry. 

Poultry intake was also linked to a higher risk for heart disease, but the implications of that finding aren't clear. The study researchers didn't have information on how food was prepared, and fried chicken and wings aren't the same as grilled chicken on a salad. "We need further research to make recommendations on how much poultry people should consume," says study author Norrina Allen, Ph.D., associate professor of epidemiology at the Northwestern University Feinberg School of Medicine in Chicago.

Strength in Numbers

While a 3 to 7 percent increase in risk may sound small, the study's authors believe those numbers may carry a lot of weight. "We had a large group of individuals and very detailed information about their diet," Allen says. "With so many people, we could really understand the effects of meat on both mortality and cardiovascular disease."

More On Healthy Eating

The findings were significant for other reasons as well. "This is a study of considerable size and careful methods," says David Katz, M.D., M.P.H., founding director of Yale University's Yale-Griffin Prevention Research Center in Derby, Conn. "The associations between meat intake, especially processed meat, and adverse health effects are consistent with virtually all prior research on the topic."

The study also showed that as consumption increased, so did the risks. And, Katz says, even small shifts in risk for individuals can add up to huge differences when it comes to public health. "At the level of the entire U.S population, a 3 percent increase in annual mortality would be 9 million excess deaths per year," he says.

Eat Meat—or Not?

This study is a counterpoint to a controversial study published in the Annals of Internal Medicine last fall that dismissed the connection between eating meat and negative health effects. "The study contradicted most of the prior work on this subject, and contradicts this [current] study as well," Allen says.

The researchers of the Annals study based their conclusions on what they described as the weakness of methods used to conduct nutrition research compared with drug studies, for example, where one group of people gets the drug and the other gets a placebo. Most diet studies, including this new one, are observational, looking at people's habits and some health outcomes over time. "As with all dietary research based on observational studies, not gold-standard randomized controlled trials, the detection of cause and effect relationships is not exact," says Lydia A. Bazzano, M.D., Ph.D., M.P.H., professor of nutrition at the Tulane University School of Public Health and Tropical Medicine in New Orleans.  

According to Bazzano, the findings of this study and other research suggest eating too much meat isn't good for you. "Given the consistency of most studies on red and processed meats, there is likely a small but cumulatively important effect on health outcomes like heart disease and all-cause death," she says. And there have been randomized controlled trials, such as the PREDIMED, OmniHEART, and DASH studies, that found that a high intake of fruits, vegetables, legumes, whole grains, nuts, monounsaturated fats like olive oil, and fish are linked with better health, she says.

"Each of us is going to have to make a decision about how we're going to balance our diets, and lean toward the healthier option when we can," Allen says. "We'd suggest that people think carefully about red meat and processed meat, and try to consider other sources of protein, like beans and nuts, that we know have positive benefits."