Good news for coffee lovers—including those who indulge heavily: Yet another study has found a link between drinking coffee and a longer life.
“This study provides further evidence that coffee drinking can be part of a healthy diet and offers reassurance to coffee drinkers,” wrote the National Cancer Institute (NCI) researchers, who analyzed data from nearly 500,000 people through the U.K. Biobank, a large-scale genomic and health database. The study took place over 10 years and the findings were published in the journal JAMA Internal Medicine.
The results were encouraging for coffee drinkers of all stripes; decaf devotees, instant coffee lovers, those who have variants of the genes associated with metabolizing caffeine, even people who drink up to eight cups of coffee per day—drinking coffee was associated with a lower mortality risk over the study period compared to non-coffee drinkers.
So is all of the glowing research around coffee consumption scientifically sound, or yet another case of over-hyped public health reporting lacking nuance? Let’s take a look at the data.
First things first: Correlation does not imply causation. Simply drinking coffee isn’t necessarily a health panacea. But the existing literature, including meta-analyses aggregating dozens of coffee studies involving millions of people, do show some notable associations between people who report drinking more coffee and protective effects against cardiovascular disease (the number one killer of Americans) like heart disease and stroke. Aaron Carroll, a pediatrician and professor of pediatrics who writes public health-related columns for the New York Times rounds up some of the numbers:
[In 2014], a systematic review and meta-analysis of studies looking at long-term consumption of coffee and the risk of cardiovascular disease was published. The researchers found 36 studies involving more than 1,270,000 participants. The combined data showed that those who consumed a moderate amount of coffee, about three to five cups a day, were at the lowest risk for problems. Those who consumed five or more cups a day had no higher risk than those who consumed none.
Carroll goes on to note that, while individual studies have suggested a possible link between excess coffee consumption and cancer, aggregated analyses don’t necessarily find the same correlation, and coffee may even have a protective effect against certain cancers like liver cancer.
The rub with these studies is that they tend to be observational ones, and those come with limitations. For instance, they rely on self-reported information and may not control for every relevant factor. Randomized control trials pitting study participants head to head in a controlled setting could help provide more definitive answers on precisely how coffee affects your health. Then again, the data that is available overwhelmingly suggests that, at the very least, it’s not bad for the vast majority of people, and it might even be good for many (provided you’re not overloading your drink with milk and sugar).
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