Epidemiology is Much Worse For You Than Red Meat
“Red meat is not bad for you. Now blue-green meat, that’s bad for you!”—Tommy Smothers
I generally try to avoid writing about meaningless studies that should be ignored. First, there are a lot of them. Second, I don’t want to attract more attention to them than they already get in the media. But sometimes a meaningless study seems to perfectly confirm what we already wanted to believe. Then a feedback loop of reader gullibility and media misunderstanding leads inevitably to reaching a conclusion entirely unsupported by the science. Then I feel obligated to shine some light on the confusion.
This week’s expedition into folly was occasioned by a ” target=”_blank”>all red meat is bad for you”.
Observational studies have almost never steered us towards the truth. Remember that observational studies suggested that estrogen prevents strokes and heart attacks. It took a randomized study to show that it doesn’t. That’s because without randomization you never know if the people that are choosing to eat red meat are different from the people who don’t in some important way that increases their mortality but has nothing to do with the meat. For example, in this study the people who ate more meat were less likely to be physically active, more likely to be current smokers, to drink alcohol, and to be overweight than those who ate less meat. The authors of the study used statistical methods to account for these differences, but there were almost certainly other differences that could not be guessed or accounted for.
Also, an observational study can’t tell us in which direction the causal arrow points. Meaning, if sick people craved more meat, then the link between the two would be due to high mortality causing more meat eating, not the other way around.
So this study teaches us absolutely nothing about a putative link between eating meat and death. It should have been completely ignored by the media, and it doesn’t deserve a moment of your attention.
But let’s take the study’s data at face value and see what all the media hullabaloo is about. The study found that an increase of one serving of unprocessed red meat per day was associated with a 13% increase in mortality, and a 20% increase for processed meat. Let’s take the higher number, 20%, that’s terrible right? That must amount to people dropping dead in droves soon after biting into their hot dogs.
The study followed people for a total of 2,960,00 person-years, during which almost 24,000 deaths were counted, for an average of 0.0080 deaths per person-year. 20% of that is 0.0016 deaths per person year, which is one additional death for 619 person-years.
So let’s pretend that the link between red meat and death is real (which is completely unsupported by this study) and let’s imagine two groups of people. The first group is composed of 100 vegetarians. The second group is 100 people who eat one serving of red meat daily, perhaps the delicious burger in the picture above, which happens to be from “Mmmmm… Burger.”—Homer Simpson
” target=”_blank”> Risks: More Red Meat, More Mortality (NY Times Vital Signs)
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