Drinking moderate amounts of coffee was linked to a lower risk of death in a new study, though experts caution there are still important unknowns.
The study published in the journal Annals of Internal Medicine used data from 171,000 people in the United Kingdom over a seven-year period, and found up to a 30 percent reduction in the risk of death.
The association with lower risk of death held for both people who drank unsweetened coffee and those who put sugar in it. The most benefit was found for people who drank moderate amounts, about two to three cups per day.
However, there are still important limitations that mean it is not definitively clear that coffee-drinking is actually causing the lower risk of death.
Christina Wee, an associate professor at Harvard Medical School and a deputy editor of the journal, wrote in an accompanying editorial that the study tried to control for other factors like socioeconomic status.
But she noted that such efforts to isolate the effects of coffee drinking alone are not perfect.
“Nonetheless, the decision whether to consume coffee (and whether to add sugar) is not a random event and is influenced by difficult-to-measure factors, including occupation and work demands and hours, socioeconomic and emotional stressors, the availability of leisure time, and intolerance to coffee from uncaptured health or clinical reasons, to name just a few,” she wrote.
A safer assumption, she wrote, is that coffee-drinkers at least do not need to quit for health reasons.
“Although we cannot definitively conclude that drinking coffee reduces mortality risk, the totality of the evidence does not suggest a need for most coffee drinkers—particularly those who drink it with no or modest amounts of sugar—to eliminate coffee,” she wrote. “So drink up—but it would be prudent to avoid too many caramel macchiatos while more evidence brews.”
The study authors, from Southern Medical University in Guangzhou, China, also wrote that coffee is a “complex mixture,” and it is difficult to isolate what part of it could be having effects on mortality.
“Of note, many of the observed associations (including our findings) between high coffee consumption and morbidity and mortality are present with caffeinated as well as decaffeinated coffee, and thus it seems unlikely that caffeine alone can explain all potential health effects of coffee,” they write.