When most people think of coffee, they focus on caffeine. But coffee beans also have more than 100 biologically active compounds with properties that benefit the heart and cardiovascular system.

A series of three studies presented at the American College of Cardiology 71st Annual Scientific Session suggest that whether or not a person has heart disease, drinking coffee is associated with a lower risk of heart disease and arrhythmias. It also lowers mortality risk.

The findings should reassure coffee lovers that coffee doesn’t cause heart disease or make it worse, senior author Peter Kistler, head of arrhythmia research at the Alfred Hospital and Baker Heart Institute in Melbourne, said in a statement. “Our data suggest that drinking coffee should be included as part of a healthy diet for those with and without heart disease.”

Coffee beans have more than 100 biologically active compounds with properties that benefit the heart and cardiovascular system.

The Australian scientists used data on over 500,000 people who were part of the UK Biobank, a long-term prospective biomedical database and research resource. Participants, who were followed for at least 10 years, reported how many cups of coffee they drank per day — from one to five or more cups.

For the first study, data were analyzed from more than 380, 000 people, who did not have heart disease when they were entered into the database, to see if they developed heart disease or had a stroke during the 10-year follow up period. Those who drank two or three cups of coffee per day got the most benefit: they were 10 to 15 percent less likely to develop arrhythmias, heart failure, coronary heart disease or die from any cause. The risk of stroke or dying from a heart-related condition was lowest among those who drink one cup of coffee per day.

The relationship between coffee consumption and the development of new arrhythmias was U-shaped. Those who drank two or three cups of coffee per day had the greatest decrease in arrhythmia risk, while those who drank more or fewer cups had a smaller decrease in risk.

Coffee even helped people with atrial fibrillation. Those who drank one cup of coffee per day had almost a 20 percent decrease in mortality risk compared to those who did not drink coffee.

The second study analyzed data from more than 34, 000 people who had cardiovascular disease at baseline. Among those with some form of cardiovascular disease, drinking two or three cups of coffee per day reduced the risk of death from any cause.

Coffee even helped people with atrial fibrillation. The second study found that among the more than 24,000 people with arrhythmias at baseline, drinking coffee reduced the risk of death. For example, those with atrial fibrillation who drank one cup of coffee per day had almost a 20 percent decrease in mortality risk compared to those who did not drink coffee.

The findings of the third study further supported coffee’s protective effect. It didn’t matter whether someone drank instant or ground coffee, or caffeinated or decaf. Two to three cups of coffee per day reduced the risk of arrhythmias, heart failure, stroke and atherosclerosis.

There was one exception: compared to caffeinated coffee, decaf had no effect on arrhythmia risk, though it did lower the risk of most cardiovascular diseases, with the exception of heart failure.

More studies are needed to see if these findings are applicable to other populations, the researchers caution, because those enrolled in the UK BioBank are mostly white, and the findings will need to be validated in a randomized clinical trial. That the amount of coffee participants consumed was self-reported is also a limitation of the findings.

Though submitted for publication, the series of studies presented at the ACC annual meeting has not yet been accepted or published in a peer-reviewed journal, Kistler told TheDoctor in an email.