According to the researchers, the patterns they found between heart health and coffee drinking are not causal—meaning coffee is not directly responsible for improved heart health, and more studies are needed to make sense of the correlation.
“There is not yet enough clear evidence to recommend increasing coffee consumption to decrease the risk of heart disease with the same strength and certainty as stopping smoking, losing weight, or exercising,” senior author of the study David Kao, M.D., said in a news release.
That said, the connections they found were interesting and do support the idea that coffee can be part of a heart-healthy diet.
Here’s what they observed: Two of the studies (published in Framingham Heart and Cardiovascular Health) saw a 5 to 12% decrease in heart failure per coffee cup per day, compared with no coffee consumption, over the course of three decades.
Other studies made arguments for having two cups per day, like the Atherosclerosis Risk in Communities Study, which showed a 30% lower risk of heart failure in people who drank at least two cups of coffee, compared to those who drank one or less.
The most consistent finding, seen in all three studies, revealed that people who drank one or more cups of caffeinated coffee per day lowered their risk of long-term heart failure. When analyzing the data further, the researchers concluded that caffeine was at least partially related to the heart-health benefits of drinking coffee.
“The association between caffeine and heart failure risk reduction was surprising. Coffee and caffeine are often considered by the general population to be ‘bad’ for the heart because people associate them with palpitations, high blood pressure, etc.,” Kao says. “The consistent relationship between increasing caffeine consumption and decreasing heart failure risk turns that assumption on its head.”