Morning Cup of Coffee Can Affect Heart Rhythms

Your daily cup of joe might be a quick pick-me-up, but it comes with a mixed bag of good and not-so-good effects on your health, a new study reports.

Drinking coffee helps people stay more active, but it also significantly robs some of sleep, researchers say.

And while java doesn’t seem to cause irregular rhythms in the upper chamber of the heart, it can do so in the lower chambers, according to findings presented Sunday at the online annual meeting of the American Heart Association.

“People should understand that this extremely commonly consumed beverage really does have substantive effects on our health, and they’re variable,” the study said. “It’s not that coffee is necessarily all good or all bad. It’s very likely that whether it’s net good or net bad depends on a combination of factors.”

Physicians have long considered caffeine a potential heart health risk, since it is a stimulant that increases heart rate. But prior studies on the subject have produced results that were “all over the place,” the study said.

“A very common question we get almost every week from patients is: Can I drink coffee? Especially in patients with atrial fibrillation,” a heart rhythm disorder that increases risk of stroke and heart attack, the study said.

For this clinical trial, the trial team recruited 100 coffee drinkers and fitted them with several devices to continuously record their health — a Fitbit, a heart monitor and a blood glucose tracker.

Over two weeks, participants were randomly assigned on a daily basis to either drink as much coffee as they liked or to forgo it.

The researchers then tracked the changes within each person and between people that occurred when they were either exposed to coffee or went without.

The study found no evidence that coffee consumption created any irregular rhythms within the atria, the upper chambers of the heart. That’s good news, since one of the major medical concerns about coffee has been whether it might promote atrial fibrillation, a potentially dangerous condition.

But they did find that coffee consumption could cause the ventricles — the lower chambers of the heart — to skip beats.

Coffee also had dramatic effects on two other major factors in your health — physical activity and sleep.

On days they were randomly assigned to drink coffee, participants on average took about 1,000 more steps than they normally would, Marcus said.

On the other hand, coffee tended to rob people of sleep.

Folks who were genetically inclined to metabolize coffee more quickly did not exhibit any significant relationship between their coffee consumption and sleep deprivation.

Participants in this study were relatively young and healthy, with an average age of 38 and an average BMI on the high end of healthy — “not typical of the patient population we see in clinical practice,” who are older and have one or more health problems.