I know Harvard researchers are smart, I really do. Yet I have to question the latest study reporting that eating red meat is associated with premature death. Published in the Archives of Internal Medicine, the paper analyzed the relationship between mortality and red meat consumption in a total of 121,342 healthcare professionals and concluded that:
Greater consumption of unprocessed and processed red meats is associated with higher mortality risk… replacement of red meat with alternative healthy dietary components may lower the mortality risk.
As a researcher, I know full well that it’s almost impossible to prove a cause-effect relationship. This is particularly difficult in human studies where other dietary and lifestyle factors have to be accounted for. After all, if you have ketchup on your steak, does the lycopene prevent against prostate cancer? “Associated with” is therefore absolutely the correct terminology for the paper’s authors to use. Alas, in the minds of so many, “associated with” translates to “causes” (especially when it’s a bad news story), and everybody panics accordingly.
The results of this report need to be put into context with our other lifestyle choices. If, as reported, eating unprocessed or processed red meat increases the relative risk of mortality by 13% and 20% respectively, how does that compare to all our other daily activities – driving a car, drinking a glass of wine or eating a candy bar? How do we weigh the risk of consuming a steak or slice of pepperoni pizza against the bottle of Mountain Dew or unwashed raw carrot? After all, during the BSE crisis in the UK, data suggested that the risk of dying from falling out of bed and suffering a fatal head injury was far greater than that from contracting vCJD, yet there was immense consumer concern relating to the perceived dangers of beef consumption.
Relative risk is not a measure that many people understand. Within this study, the absolute mortality risks (i.e. the probability of any one person dying) paint a rather different picture. Out of every 100 men, 1.23 men consuming three servings of unprocessed meat (the equivalent of one 9-oz steak) per week were likely to die, versus 1.30 men eating 6 oz of processed meat (bacon, sausage etc) per day (42 oz per week). Given the small difference in those mortality risks (which were similar for women) yet the huge difference (9 oz vs. 42 oz) in weekly meat consumption, we would be better served by focusing more on other factors (bodyweight, exercise, genetic propensity to specific diseases) that contribute the vast majority of our absolute mortality risk rather than assuming that we can live forever if we only replace a hamburger with a vegetarian meatloaf.
Since this study hit the headlines my Facebook newsfeed predictably been over-run by anecdotes about grandparents who lived to the ripe of age of 101 years while eating bacon and eggs for breakfast, corned-beef hash for lunch and three pork chops (with extra heavy cream in the whipped potatoes) for dinner. Without wishing to be flippant, the one certainty in this life is that we’ll all die at some point – if I restricted my meat intake to the suggested 3 oz per day (or less) I have a sneaking feeling that I might not live forever, but it’d sure feel like it.