I've recently been bombarded with e-mails regarding a recent study which seemed to conclude that coffee consumption can be linked with longevity. The study was not funded by the coffee industry, and was published in the highly regarded New England Journal of Medicine - so everything seemed to be fine.
However, going for an extra coffee cup because of this study would be a major mistake - and it is exactly this kind of misinterpretation from the newspapers which makes it extremely hard for researchers to deliver their results precisely to the masses. The journal's editor and an outside expert on the matter already explained it wouldn't be a good idea to encourage coffee consumption even further than it is today.
What researchers found is that men who drink coffee (two or more coups a day) had about a 10 percent lower risk of dying over a 13-year period compared with those who drank none.
“It’s important to interpret this finding cautiously,” said study author Neal Freedman, an investigator at the National Cancer Institute. “It may provide reassurance to those drinking coffee that coffee doesn’t increase their risk of death overall. But whether it really reduces death? We can’t say that for certain.”
The thing is, when you do this kind of research, you're almost bound to make a mistake due to all the factors you have to take into consideration. This is also the opinion of the journal's director.
“I’m not a fan in general of epidemiological studies of this type because they can be confounded by variables,” Dr. Jeffrey M. Drazen, editor-in-chief of the New England Journal of Medicine, told me in an interview. While the researchers took into account more than a dozen differences (such as smoking, weight, education) that distinguished heavy coffee drinkers from those that abstained, Drazen said they couldn’t account for everything.
Here's what happens, basically: people are all different. People who drink coffee, on average have a different profile altogether: they smoke more, exercise less, are less educated, etc - so scientists have to insert some parameters to even these things out and eliminate their effect, in order to leave out only the effect of coffee - and this is almost impossible.
“People who drink a lot coffee are very different from those who don’t. They smoke more, have a lower level of education, exercise less, and eat more red meat, according to this study and previous ones. Any time you try to adjust for all these factors, the adjustment is likely to be inaccurate and incomplete — and this one in the study is particularly bad.”, said Dr. Steven Nissen, chair of cardiovascular medicine at the Cleveland Clinic, said the study is apt to be misinterpreted by the public at large.
All in all, this study received oh so much more attention than it deserved, because it was exactly the spark which re-lit and age-old debate. Basically, drinking coffee might help prolong your life; it might shorten it. We just don't know for sure yet.
