Professor Christopher X Wong.

A cup of coffee a day could protect against a common heart condition that is a cause of heart failure, stroke and premature death.

Atrial fibrillation (AF)– an irregular heartbeat – affects one in three people at some point in their lifetime. Now in game changing research led by University of Adelaide and University of California, San Francisco (UCSF) researchers have discovered a surprising heart health ally in coffee.

A randomised clinical trial was carried out on 200 AF patients from Australia, the United States and Canada. Half of the participants were required to consume at least one cup of coffee or espresso shot each day, while the other group had to abstain from coffee and caffeinated products all together. Patients were then monitored regularly over six months, with any episodes of AF verified by physicians through electrocardiograms and similar devices.

“The results were astounding. In contrast to conventional wisdom, we found the coffee drinkers experienced a significant reduction in AF compared to those who avoided coffee and caffeine,” said first author Professor Christopher X. Wong from the University of Adelaide and Royal Adelaide Hospital.

“This is surprising as it goes against the common assumption by doctors and patients that coffee worsens heart rhythm disorders such as AF. Doctors have always recommended patients with problematic AF minimise their coffee intake, but this trial suggests that coffee is not only safe but likely to be protective.”

The DECAF (Does Eliminating Coffee Avoid Fibrillation) trial is the first randomised clinical trial looking at the link between coffee and AF.

Researchers found a 39 per cent reduction in the risk of a recurrent AF episodes in the coffee consumption group compared to those who avoided coffee and caffeine, and believe there are several possible explanations for this positive result.

“Coffee increases physical activity which is known to reduce AF. Caffeine is also a diuretic which could potentially reduce blood pressure and in turn lessen AF risk. Several other ingredients in coffee also have anti-inflammatory properties that could have positive effects,” said senior author Professor Gregory Marcus from the Division of Cardiology at UCSF.

AF is a condition which prevents the heart from pumping blood properly, increasing the risk of blood clots and stroke. Around half a million Australians and more than 10 million Americans have the long-term condition, which is linked to high blood pressure, obesity and other heart diseases.

“The number of people with AF is rising and the risk of developing the condition increases with age. As a result, there’s certainly a lot of interest in ways to reduce the burden of the condition. Our study provides more clarity on the effect of caffeinated coffee on AF patients and should change the medical advice we give to patients,” said Professor Marcus.

Coffee is the most popular caffeinated beverage in Australia, with a recent survey revealing 75% of Australians drink coffee each day.

“Based on these results, coffee-drinking patients with AF can safely continue to enjoy their coffee. Furthermore, it may be worth investigating whether AF patients who don’t drink coffee should actually consider starting,” said Professor Wong.

The research has been published in The Journal of the American Medical Association and has been supported by the National Health and Medical Research Council, the Hospital Research Foundation, and The Heart Foundation.

The University of Adelaide and the University of South Australia are joining forces to become Australia’s new major university – Adelaide University. Building on the strengths, legacies and resources of two leading universities, Adelaide University will deliver globally relevant research at scale, innovative, industry-informed teaching and an outstanding student experience. Adelaide University will open its doors in January 2026. Find out more on the Adelaide University website.

* Case study available for interviews on request. A pre-recorded interview with Professor Wong and B-roll footage is also available for media outlets.

**Jessica Stanley, **Media Officer, University of Adelaide. Phone: +61 0422 406 351, Email: jessica.stanley@adelaide.edu.au