Finally: hard evidence that meat consumption shortens life expectancy – at least as far as epidemiological research is capable of providing hard evidence – comes from researchers at Harvard, led by Walter Willett and Frank Hu. Their study in the Archives of Internal Medicine tells those who want to pursue a protein-rich diet what the healthy alternatives are for meat.
Researchers have known for years that a high intake of red meat – a name that covers muscle meat of mammalian origin – increases the risk of cardiovascular disease and reduces life expectancy. [Arch Intern Med. 2009 Mar 23; 169(6): 562-71.] The organic iron in red meat is a bit too much of a good thing for many adults; and substances such as heterocyclic amines - which are created when meat is fried - are pretty unhealthy.
But do you live longer if you replace red meat with other, healthier, protein-rich foods? Until now there was no study that had shown this.
Harvard researchers used data from the Healthy Professionals Follow-up Study and the Nurses Health Study. The first study followed forty thousand men between 1986 and 2008; the second eighty thousand women between 1980 and 2008. When the Harvardians put all the data together they saw that for each time red meat was consumed in a day, the mortality risk rose by 16 percent. Processed meat [Processed red meat] in particular, such as salami, bacon, hot dogs, boosted the risk of mortality.
In 2005, so 11 years later, the researchers worked out which of the participants were still alive. This way they were able to conclude that a high degree of life satisfaction reduced the risk of mortality in men [immediately below] and women [bottom table]. The effect was particularly strong among the women.
In the figures above the upper graph shows the risk of dying for men. The lower graph shows the risk for women.
The relationships the Harvard researchers found were statistically significant, even though the risks they discovered were not big. Alcohol abuse, smoking and overweight are all riskier activities. On the other hand though: if all the participants in the studies ate no more than 42 g red meat per day, then 9.3 percent of the deceased men and 7.6 percent of the deceased women would still have been alive in 2008.
The researchers were able to calculate the effect of substituting nuts, chicken, fish, low-fat dairy and other foods for red meat. As you can see below, nuts are the healthiest meat substitutes. But nuts are not a good source of protein. In second place is chicken. And chicken is a good source of protein.
Arch Intern Med. 2012 Apr 9;172(7):555-63.