Is that extra bite of red meat really going to kill you? If it's your fourth ounce in a day, it might.

People who eat the most red meat daily (about four ounces) are about a third more likely to die over a given decade than those who eat the least (about 19 grams), according to new research set to be published tomorrow in the Archives of Internal Medicine. Conversely, those who eat the most white meat have an 8 percent lower risk of dying compared with people who eat the least.

The findings are based on the eating habits of half a million men and women who were followed for 10 years by scientists at the National Cancer Institute (NCI). The researchers did not calculate the absolute risk of dying based on a red-meat vs. white-meat diet, co-author Rashmi Sinha, a senior investigator there, tells ScientificAmerican.com. But she writes that if everyone lowered  his or her red meat intake to 19 grams a day or less, 11 percent fewer men and 16 percent fewer women would die.

It's unknown why white meat may protect against death, and the relationship between red meat and dying isn’t entirely clear, Sinha says. But she notes that cooking red meat at high temperatures forms carcinogens including heterocyclic amines (chemicals that form when amino acids and creatine, a compound important to muscle energy, react) and polycyclic aromatic hydrocarbons (chemicals formed during grilling). In addition, Sinha says, iron in the meat may increase cell damage and the creation of N-nitroso compounds, which form from reactions with other chemicals and may be associated with cancer. Red meat also contains saturated fat, which has been linked to an increased risk of heart disease and cancer of the breast and colon.

Updated at 9:55 a.m. March 24 to clarify that increased risk of death is over a 10-year period.

Image of steak © iStockphoto/David Smith