A new study says that people under the age of 55 who drink four or more cups of coffee a day die younger -- of all causes. The study, from Mayo Clinic Proceedings, followed 44,000 people of both sexes for almost two decades, Forbes reports.
Lifestyle factors like coffee consumption, diet, exercise, smoking and weight were controlled for. A total of 2,500 people died during the study period (87% of them men).
The results of the analysis: People under 55 who drank more than 28 cups of coffee per week were more likely to die of almost any cause than people who drank less. Men were twice as likely to die from any cause and women were 56% more likely.
Before you flush your cup of Joe, there were some drawbacks to the study. One is that no one could explain the coffee-death link. Some came up with some good hypotheses, though: coffee's ability to boost epinephrine (adrenalin) levels in the body; its inhibition of insulin function; and the fact that it may raise blood pressure and homocysteine levels, which are both known to increase heart risk (though since heart disease was not increased in the study, these seem less likely).
Another big hole in the study is the whole age issue: the coffee-death relationship was only true for people under 55, not for older people. That could mean that people who are dying that young were predisposed to fatal health problems to begin with. Study author Chip Lavie points out that heavy coffee drinkers differ in a number of ways from non-coffee freaks, so there may be other things going on that researchers haven't figured out yet. (Maybe they're drinking so much coffee to compensate for some abnormal biological processes?) The authors suggest that since heart disease wasn't increased among heavy coffee drinkers, the big "C" -- cancer -- might be at play in their early demises.
"Certainly, one would think that the main non-CV cause of death would be cancer, but we did not specifically assess this." (Ack, why not?) "And with cancer, one would really want to know cause-specific as opposed to cancer in general -- we will probably try to assess this, although this is not quite as easy as one may think," Lavie told Forbes.
The gist: There could be a lot of other factors at play in the early deaths among big coffee drinkers. "It is impossible to know if this association is causal or just an association," says Lavie, "so one does not want to over-state or over-hype the dangers of drinking more than 28 cups per week, although I personally will make an effort to keep my cups at three or less most of the time."
Three venti cups, right?