http://www.cnn.com/2012/03/12/health/red-meat-shorten-lifespan/index.html
From the web page:
Using data from two long-running studies of health professionals, researchers tracked the diets of more than 121,000 middle-aged men and women for up to 28 years. Roughly 20% of the participants died during that period.
On average, each additional serving of red meat the participants ate per day was associated with a 13% higher risk of dying during the study. Processed red meat products -- such as hot dogs, bacon, and salami -- appeared to be even more dangerous: Each additional daily serving was associated with a 20% higher risk of dying.
Based on these findings, the researchers estimate that substituting one daily serving of red meat with fish, poultry, nuts, legumes, whole grains, or low-fat dairy products would reduce the risk of dying in this stage of life by 7% to 19%. If everyone in the study had slashed their average red-meat intake to less than half a serving per day, the researchers say, 9% of deaths among men and 8% of deaths among women could have been prevented.