There’s a trope in science news coverage that plays out again and again and again: the coffee study. Researchers observe a large population, measure their coffee drinking habits with a questionnaire, and crunch the data to see how the ubiquitous beverage affects our health. These studies have demonstrated, generally, that folks who drink a few cups a day seem healthier than those who don’t.
News reporters rehashed a common coffee claim this week that should have made you turn your head: that coffee “reduces the risk of death,” first reported in a press release from the European Society of Cardiology. Science has not, and may never, reduce the risk of death. The risk of death is 100 percent—though others clarify it may reduce the risk of early death.
These headlines hail from a study presented last week at the European Society of Cardiology conference in Barcelona. The study’s results included data from almost 20,000 university students, collected via questionnaires on various factors including their coffee consumption and other lifestyle habits. Of the entire cohort, 335 died during the follow-up years after answering the questionnaire. A quick number crunch revealed that the coffee drinkers had a 65 percent lower chance of being among the dead than those who never drank coffee.
These studies are a popular way to get a feel for a trend or mechanism that might be worth exploring with more detailed research. But notice here: the researchers didn’t feed people coffee in a controlled experiment, or monitor consistent coffee intakes. They don’t say how the 335 people died in the conference abstract (the only data included in the press release) nor do offer a mechanism for how coffee might kill you, or mention the fact that coffee might have different effects on different people.
This is not the last coffee study you will see, and is probably not the last time you’ll here that something reduces the risk of death, either. Just know that all 20,000 of those study participants will eventually die, as will you and the rest of the Earth’s population. The risk of death is 100 percent.