For years, doctors have warned people with heart problems to stay away from coffee, fearing that caffeine could make their condition worse.
But a new study from the University of California, San Francisco (UCSF), and the University of Adelaide suggests the opposite might be true.
According to the research, drinking just one cup of caffeinated coffee a day could actually protect against atrial fibrillation, also known as A-Fib—a common heart rhythm disorder that affects millions of people worldwide.
Atrial fibrillation happens when the heart’s upper chambers beat out of sync with the lower chambers, creating a rapid and irregular rhythm.
This can cause feelings of fluttering or pounding in the chest, shortness of breath, fatigue, and dizziness. If left untreated, A-Fib can lead to serious health problems such as stroke, heart failure, and other heart-related complications.
The condition is becoming more common as the population ages and obesity rates rise. In the United States alone, more than 10 million adults are living with A-Fib, and researchers estimate that one in three people may develop it during their lifetime.
The new study, published in *JAMA*, offers a hopeful message for coffee lovers. The research team found that people who drank at least one cup of caffeinated coffee a day had a 39% lower risk of recurrent A-Fib compared to those who avoided caffeine altogether.
This is the first clinical trial to test whether caffeine might help or harm people with atrial fibrillation. The study, cleverly named DECAF—short for “Does Eliminating Coffee Avoid Fibrillation?”—followed 200 patients who were scheduled to undergo electrical cardioversion, a procedure that uses a brief electric shock to restore the heart’s normal rhythm.
Participants were randomly divided into two groups. One group was told to drink at least one cup of caffeinated coffee or an espresso shot daily for six months, while the other group was instructed to avoid coffee, tea, and other caffeine-containing drinks. At the end of the study, the coffee-drinking group showed significantly fewer A-Fib episodes.
Dr. Gregory Marcus, senior author of the study and a leading expert on atrial fibrillation at UCSF, explained that caffeine might protect the heart in several ways. “Coffee increases physical activity, which is known to lower the risk of A-Fib,” he said.
“It also acts as a mild diuretic, which could help reduce blood pressure. And coffee contains several compounds with anti-inflammatory properties that may benefit the heart.”
Lead researcher Dr. Christopher Wong from UCSF and the University of Adelaide said the results were surprising. “Doctors have traditionally told A-Fib patients to avoid coffee, but our findings suggest that coffee is not only safe but may even help protect against heart rhythm problems,” he noted.
Beyond caffeine, researchers believe coffee may offer other indirect benefits. People who drink coffee often replace less healthy options, such as sugary soft drinks, which could further reduce their risk of heart issues.
Previous studies have also found that moderate coffee consumption is linked to lower risks of diabetes, liver disease, and even certain types of cancer. These combined effects may help explain why coffee seems to support overall cardiovascular health.
However, the scientists cautioned that this doesn’t mean everyone should start drinking large amounts of coffee. Too much caffeine can still cause problems like anxiety, sleep disturbance, and heart palpitations in sensitive individuals.
The key, they emphasized, is moderation. One to two cups of coffee a day appears to be beneficial for most people, especially when part of a balanced diet and healthy lifestyle.
The findings from this study challenge long-held beliefs about caffeine and the heart. For decades, medical advice has leaned toward avoidance, but this research suggests that a morning cup of coffee might actually do more good than harm.
By lowering inflammation, reducing blood pressure, and encouraging physical activity, coffee could become a simple and natural way to support heart rhythm health.
In summary, this study provides encouraging evidence that moderate coffee drinking may help prevent irregular heartbeats in people at risk of atrial fibrillation.
It also opens the door for more research to confirm how caffeine and other compounds in coffee influence the heart over time. For now, coffee drinkers can feel reassured that their daily cup might not just wake them up—it could also help keep their hearts beating steadily.
If you care about heart health, please read studies about top 10 foods for a healthy heart, and how to eat right for heart rhythm disorders.
For more health information, please see recent studies about how to eat your way to cleaner arteries, and salt and heart health: does less really mean more?
The study is published in JAMA.
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