A new study from Harvard School of Public Health (HSPH) researchers has found that red meat consumption is associated with an increased risk of total, cardiovascular（心血管的） , and cancer mortality. The results also showed that substituting other healthy protein sources, such as fish, poultry（家禽） , nuts, and legumes（豆类，蔬菜） , was associated with a lower risk of mortality. The study will be published online in Archives of Internal Medicine on March 12, 2012.

"Our study adds more evidence to the health risks of eating high amounts of red meat, which has been associated with type 2 diabetes, coronary heart disease, stroke, and certain cancers in other studies," said lead author An Pan, research fellow in the Department of Nutrition at HSPH.

The researchers, including senior author Frank Hu, professor of nutrition and epidemiology at HSPH, and colleagues, prospectively observed 37,698 men from the Health Professionals Follow-up Study for up to 22 years and 83,644 women in the Nurses' Health Study for up to 28 years who were free of cardiovascular disease (CVD) and cancer at baseline. Diets were assessed through questionnaires every four years.

A combined 23,926 deaths were documented in the two studies, of which 5,910 were from CVD and 9,464 from cancer. Regular consumption of red meat, particularly processed red meat, was associated with increased mortality risk. One daily serving of unprocessed red meat (about the size of a deck of cards) was associated with a 13% increased risk of mortality, and one daily serving of processed red meat (one hot dog or two slices of bacon) was associated with a 20% increased risk.

Among specific causes, the corresponding increases in risk were 18% and 21% for cardiovascular mortality, and 10% and 16% for cancer mortality. These analyses took into account chronic disease risk factors such as age, body mass index, physical activity, family history of heart disease, or major cancers.

Red meat, especially processed meat, contains ingredients that have been linked to increased risk of chronic diseases, such as cardiovascular disease and cancer. These include heme iron, saturated fat, sodium, nitrites, and certain carcinogens（致癌物） that are formed during cooking.

Replacing one serving of total red meat with one serving of a healthy protein source was associated with a lower mortality risk: 7% for fish, 14% for poultry, 19% for nuts, 10% for legumes, 10% for low-fat dairy products, and 14% for whole grains. The researchers estimated that 9.3% of deaths in men and 7.6% in women could have been prevented at the end of the follow-up if all the participants had consumed less than 0.5 servings per day of red meat.

"This study provides clear evidence that regular consumption of red meat, especially processed meat, contributes substantially to premature death," said Hu. "On the other hand, choosing more healthful sources of protein in place of red meat can confer significant health benefits by reducing chronic disease morbidity and mortality."

Support for the study was provided by the National Heart, Lung, and Blood Institute and the National Cancer Institute.

Other HSPH authors include Qi Sun, Adam Bernstein, JoAnn Manson, Meir Stampfer, and Walter Willett.