Two new studies suggest that drinking coffee may extend your life. But you’d have to drink at least a cup a day—preferably three—and be OK with not knowing why coffee is correlated with longevity.
The health benefits were also the same regardless of whether the participants drank decaffeinated or regular coffee, suggesting that the benefit comes from coffee itself, not caffeine.
The studies, both published today in the Annals of Internal Medicine, surveyed hundreds of thousands of adults aged 35 and up across a range of different ethnic groups in the United States and Europe.
One study tracked the habits of 521,330 people across ten European countries, and concluded that coffee drinking was associated with a decreased risk of mortality overall. It didn’t matter which disease they may have died from—or even if they were killed in an accident—coffee drinkers tended to die at a lower rate.
The second study looked at 185,855 U.S. participants aged 45 to 75 and found that consuming two to three cups of coffee per day was associated with a reduced risk of heart disease, cancer, stroke, diabetes and respiratory, and kidney disease. The U.S. study included African American, Japanese American, Native Hawaiian, Latino and white participants, and found the effects to be similar across all groups except Native Hawaiians.
The average follow-up period for both studies was 16 years, and researchers adjusted for factors such as age, sex, physical activity, education, and pre-existing disease.
George Dvorsky, reporting for Gizmodo:
The researchers weren’t able to identify a causal relationship, nor were they able to explain why coffee appears to confer these health benefits. And importantly, some experts are challenging the conclusions reached in these two studies, saying the results were misleading, and that blanket statements about coffee consumption ignore the fact that, for some, caffeine is dangerous.
Other critics have pointed out that the studies didn’t account for different types of coffee, nor the concentration of coffee consumed, two factors that could alter the compounds found in the beverage.
In short, coffee might not be bad, as some reports have claimed, and it may even be good for you. Still, there are myriad variables in studies like this—far too many to control to the level scientists would need to make a definitive statement. So for now, drink coffee if you like, skip it if you don’t, and wait for the next study to be published.