People who eat the most red meat and the most processed meat have the highest overall risk of death from all causes, including heart disease and cancer.
The National Cancer Institute study is one of the largest to look at the highly controversial and emotive issue of whether eating meat is indeed bad for health.
Rashmi Sinha and colleagues looked at the records of more than 500,000 people aged 50 to 71 who filled out questionnaires on their diet and other health habits.
Even when other factors were accounted for -- eating fresh fruits and vegetables, smoking, exercise, obesity -- the heaviest meat-eaters were more likely to die over the next 10 years than the people who ate the least amount of meat.
"Red and processed meat intakes were associated with modest increases in total mortality, cancer mortality, and cardiovascular disease mortality," Sinha and colleagues wrote in the Archives of Internal Medicine.
They divided the volunteers into five groups, called quintiles. Between 1995 and 2005, 47,976 men and 23,276 women died.
The quintile who ate the most red meat had a higher risk for overall death, death from heart disease and cancer than the men and women who ate the least red meat.
The researchers said thousands of deaths could be prevented if people simply ate less meat. "For overall mortality, 11 percent of deaths in men and 16 percent of deaths in women could be prevented if people decreased their red meat consumption to the level of intake in the first quintile," Sinha's team wrote.
HELPING THE ENVIRONMENT
Many studies have shown that people who eat less meat are healthier in many ways, and Sinha's team noted that meat contains several cancer-causing chemicals, as well as the unhealthiest forms of fat.The U.S. government now recommends a "plant-based diet" that stresses fruits, vegetables and whole grains.
Barry Popkin, an expert in nutrition and economics at the University of North Carolina, said the study was unusually thorough and careful.
Eating less meat has other benefits, he said, and governments should start promoting this. For instance, farming animals for meat causes greenhouse gas emissions that warm the atmosphere and uses fresh water in excess, he said.
"I was pretty surprised when I checked back and went through the data on emissions from animal food and livestock," Popkin said in a telephone interview."I didn't expect it to be more than cars."
Cancer experts said the study fit in with what is known from other research. "This large study provides further evidence to support the recommendations by groups such as the World Cancer Research Fund in demonstrating an association between a high consumption of red and processed meats and a increase risk of death from cancer," said Ian Olver, Chief Executive Officer of Cancer Council Australia.
