Older adults who drink coffee have a lower risk of death by about 10 percent, according to a large observational study of over 400,000 people published in The New England Journal of Medicine. The study, which followed participants aged 50 to 71 during a 14-year window, examined common causes of death, including heart and respiratory disease, stroke, injuries and accidents, diabetes, and infections. For each life-ending ailment, coffee drinking correlated with lower risk of death in both men and women, with cancer being the only condition that showed no correlation in women and a slight increase in risk of death for men who are heavy coffee drinkers.
However, while it would be easy to draw the conclusion that drinking coffee helps you live longer, the raw data from the study actually shows coffee drinkers die younger. Why? Because a number of bad habits and detriments to longevity are associated with coffee drinking, likely negating any benefits from coffee itself.
The study was conducted by researchers at the National Cancer Institute and funded by the NIH and AARP as part of a diet and health study in older Americans (unfortunately, the full article is behind a paywall, but you can access the abstract here). The data were collected via a baseline questionnaire that gauged demographic and lifestyle characteristics along with diet, then monitored until they died or the study ended.
When the data were first analyzed, coffee consumption was associated with an increase in the mortality of both men and women. To arrive at the result that coffee drinking may lower the risk of death, the researchers accounted for particularly damaging vices that coffee drinkers are more prone to engage in, such as smoking. It was only after accounting for the statistical contribution that smoking adds to increasing the rate of mortality did they arrive at the result that coffee drinkers have increased longevity.
A quote from the study indicates the bad habits that coffee drinkers are guilty of:
As compared with persons who did not drink coffee, coffee drinkers were more likely to smoke cigarettes and consume more than three alcoholic drinks per day, and they consumed more red meat. Coffee drinkers also tended to have a lower level of education; were less likely to engage in vigorous physical activity; and reported lower levels of consumption of fruits, vegetables, and white meat.
With over 170 million Americans drinking coffee and over 1 billion coffee drinkers worldwide (coffee is the second largest commodity in the world, after all), the effects of coffee on health have been researched and disputed for a long time. Previous studies have shown that coffee has multiple benefits that can fight depression, prevent diabetes, protect against liver fibrosis, and even help fight cancer, but the scope of this most recent study helps to take a much broader view of its benefits, even taking into account the known problems with observational studies. Although this study shifts the tug-of-war between the health benefits and risks of coffee back toward the healthy side, the particularly damning observation that the health benefits of coffee are negated by a slew of poor lifestyle choices is a lesson for both coffee and non-coffee drinkers alike.
But ultimately the issue of this study is, if coffee is preventative medicine, drink it up. If it’s poison, everyone should avoid it. Simple, right? Well, not exactly.
The question of whether coffee is good or bad for you is inherently a complex one. The process of roasting coffee produces over 1,000 compounds — some of which are antioxidants, while about 19 are known rodent carcinogens. These compounds create the taste and aromatic richness associated with different roasts. But the fact remains that the vast majority of these compounds have not been tested individually for their health effects and likely won’t be for a long time to come.
Furthermore, the study suffers from another longstanding problem from large-scale statistical analyses, which the authors admitted: correlation does not mean causation. In other words, it is impossible to tell whether coffee itself directly contributed to extending the lifetimes of drinkers or if coffee drinking is part of a lifestyle of people who tend to live longer.
But coffee drinkers in general can help their longevity through some simple lifestyle changes, such as quitting smoking (in case you haven’t heard that before) and joining the 35 percent of coffee drinkers who take it black, which eliminates the milk and sugar both of which are detrimental if you’re drinking 4-5 cups a day.
This study illustrates just how tricky it is to fish out all the lifestyle factors that impact health. But in the end, one thing is clear: coffee’s reputation isn’t as black as previously labeled.