Red meat kills, said the headlines.
Over on Understanding Uncertainty David Spiegelhalter did the sums to give a more nuanced explanation of how to interpret the latest figures from an American study widely reported in the media.
Forty-year old Meaty Mike, who eats a quarter-pound burger for lunch Monday to Friday, every week, cuts the length of his days – each & every one – by half an hour compared with his coeval, Standard Sam who, while similar to Mike in his general dietary habits, never eats meat for lunch.
Mike can expect (in the statistical sense) only 39 more years of life compared to Sam’s 40.
Of course nothing is certain in the world of statistics & in this case the uncertainty can be expressed by calculating the odds that Mike will actually be the first of the pair to die – at 0.53 not very different from 50:50.
There is one other big very big iff behind these calculations: that we can apply the results of a long-term observational study of American health workers directly to an English population, who may be different in several crucial dietary & other respects, particularly the average consumption of red meat & the proportion of that which is made up of beef (rather than lamb or pork) from cattle fed on corn rather than grass.
The dietary information – assessed through questionnaires every four years - must be very broad brush. And, with such observational data, an association is not proof of causation – eating a burger for lunch every day, year after year could well stand in for some other problem or disadvantage, such as living in circumstances which limit your choice of options, or being mildly depressed.
Such studies do however reinforce the sound advice to eat a varied diet, one which includes fruit & vegetables (of different colours), & does not regard meat as the only, or even main source of daily protein – cheese, beans, fish & eggs are all delicious too. It does not mean a frantic search for novelty or super foods or a particular meal magic from some other part of the world with a different climate & economy.
Too much of anything can kill you – people have died from drinking too much water, or carrot juice.
And remember, just living is guaranteed to kill you in the end.
