Coffee Study Challenges Long-Held Medical Advice on Heart Condition
New clinical evidence suggests coffee may protect against atrial fibrillation, overturning decades of cautionary advice
Dubai – Qahwa World
For years, patients diagnosed with irregular heart rhythms have heard the same warning from doctors: avoid coffee. The reasoning seemed simple — caffeine increases heart rate and alertness, so it must worsen conditions such as atrial fibrillation.
Now, a groundbreaking international study published in JAMA on November 9, 2025, has challenged that long-standing belief. The DECAF trial — short for Does Eliminating Coffee Avoid Fibrillation? — found that moderate coffee consumption actually lowered the risk of atrial fibrillation recurrence by 39 percent compared with total abstinence.Coffee Study Challenges Long-Held Medical Advice on Heart Condition
New clinical evidence suggests coffee may protect against atrial fibrillation, overturning decades of cautionary advice
For years, patients diagnosed with irregular heart rhythms have heard the same warning from doctors: avoid coffee. The reasoning seemed simple — caffeine increases heart rate and alertness, so it must worsen conditions such as atrial fibrillation.
Now, a groundbreaking international study published in JAMA on November 9, 2025, has challenged that long-standing belief. The DECAF trial — short for Does Eliminating Coffee Avoid Fibrillation? — found that moderate coffee consumption actually lowered the risk of atrial fibrillation recurrence by 39 percent compared with total abstinence.
The finding could reshape global medical advice for millions living with the world’s most common heart rhythm disorder and reignite conversations about coffee’s misunderstood role in cardiovascular health.
From Myth to Medicine
Atrial fibrillation (AF) affects more than 60 million people worldwide and is linked to serious complications including stroke, heart failure, and early mortality. Because caffeine is known to stimulate the nervous system, many clinicians have historically told AF patients to stay away from coffee altogether.
But coffee is not a simple stimulant. It is a complex natural beverage containing hundreds of bioactive compounds — antioxidants, polyphenols, and natural anti-inflammatory agents — that may benefit the cardiovascular system.
To investigate whether this complexity might hold a hidden benefit, a team of researchers led by Dr. Christopher Wong of the University of Adelaide and Dr. Gregory Marcus of the University of California, San Francisco, designed the first randomized clinical trial to directly test coffee’s effect on atrial fibrillation recurrence.
Inside the DECAF Trial
Between 2021 and 2024, 200 men and women with persistent atrial fibrillation were recruited from five major hospitals in the United States, Canada, and Australia. All participants were habitual or recent coffee drinkers who were scheduled to undergo electrical cardioversion, a procedure used to reset an irregular heartbeat to normal rhythm.
After successful cardioversion, the participants were divided into two groups:
The coffee group, encouraged to drink at least one cup of caffeinated coffee daily for six months.
The abstinence group, instructed to avoid all forms of coffee and caffeine, including decaffeinated varieties.
Both groups began with similar average coffee intake — about seven cups per week — before the experiment began. Over six months, researchers tracked all recurrences of atrial fibrillation or atrial flutter lasting 30 seconds or longer, using clinical electrocardiograms, wearable heart monitors, and implantable devices.
At the end of the study, the results were striking:
Only 47 percent of coffee drinkers experienced a recurrence of atrial fibrillation.
In contrast, 64 percent of those who abstained suffered another episode.
That difference translates to a hazard ratio of 0.61, meaning the coffee drinkers had a 39 percent lower risk of recurrence.
Just as significant, the coffee group did not show higher rates of hospitalization, stroke, or heart failure. No serious side effects were observed, suggesting that moderate coffee consumption is not only safe but potentially beneficial for patients recovering from AF.
“Astounding” Results Defy Conventional Wisdom
“In contrast to conventional wisdom, we found that coffee drinkers experienced a significant reduction in AF compared to those who avoided caffeine,”
— Dr. Christopher Wong, University of Adelaide
The study’s senior author, Dr. Gregory Marcus, added that the results provide a foundation for a more flexible approach to dietary guidance: “It is reasonable for health-care professionals to let their patients with AF consider experimenting with naturally caffeinated substances they enjoy, such as tea and coffee. However, some individuals may still find that caffeine worsens their symptoms.”
This nuance matters. The researchers emphasize that their trial involved typical coffee consumption — around one cup daily — not energy drinks or high-dose caffeine supplements. The potential benefits appear tied to natural coffee’s balanced composition, not extreme stimulation.
How Coffee Might Help the Heart
The DECAF investigators explored several physiological explanations for their unexpected finding.
Adenosine Receptor Blockade
Caffeine blocks A1 and A2A adenosine receptors, which play a role in triggering AF episodes. By preventing adenosine from shortening the heart’s electrical recovery time, caffeine may act as a mild anti-arrhythmic agent.
Anti-Inflammatory Effects
Coffee’s chlorogenic acid and polyphenols reduce systemic inflammation — an established risk factor for atrial fibrillation and many other heart diseases.
Improved Circulation and Fluid Balance
Coffee’s gentle diuretic effect can help lower blood pressure and decrease cardiac strain, indirectly reducing AF risk.
Behavioral Factors
In previous studies, habitual coffee drinkers were found to take more daily steps and maintain higher levels of physical activity, both protective against AF recurrence.
The team also noted that coffee drinkers in the trial did not replace coffee with sugary sodas or high-calorie beverages, which might have otherwise increased cardiovascular risk.
Taken together, these effects may explain why moderate coffee consumption — far from being dangerous — may actually stabilize the heart’s rhythm.
A Trial That May Rewrite Clinical Advice
The implications of this work extend beyond cardiology. Coffee is the most widely consumed caffeinated beverage on Earth, and medical advice around it influences millions of daily routines.
For decades, doctors issued cautionary statements largely based on anecdotal observations and small, uncontrolled studies. The DECAF trial provides the first causal evidence — through randomized assignment — that regular caffeinated coffee consumption is unlikely to provoke atrial fibrillation and may even reduce its recurrence.
“Among patients with atrial fibrillation, consuming about one cup of caffeinated coffee per day was linked to fewer recurrences — not more. It’s time we rethink the old advice that coffee should be avoided,” said Dr. Wong.
While the study’s participants were already accustomed to coffee, researchers believe similar results might hold for moderate new drinkers, though further trials are needed.
Limitations and Cautions
As with any clinical study, the authors acknowledge several limitations.
The trial was open-label, meaning participants knew which group they were in.
It lasted only six months and involved a modest 200 participants.
Only 69 percent of abstainers fully adhered to caffeine avoidance, possibly diluting the true benefit of coffee.
Because the cohort consisted of previous coffee drinkers, results may not apply to lifelong abstainers or to people with caffeine sensitivity.
Nevertheless, the findings remained statistically robust even after adjustments for age, medication use, and co-existing conditions. No evidence suggested harm from coffee, and adverse events were comparable between groups.
A New Understanding of Coffee and the Heart
The DECAF trial arrives amid a growing body of evidence that moderate coffee drinking supports overall heart health. Previous large-scale studies have already linked coffee to lower risks of stroke, diabetes, and all-cause mortality.
What makes DECAF unique is its focus on arrhythmia, an area long clouded by uncertainty and fear. The message emerging from this work is one of moderation and balance rather than prohibition.
A single, freshly brewed cup — perhaps the ritual that begins each morning for billions — might not just awaken the senses but gently protect the heart as well.
About the Study
The DECAF trial was conducted by the University of Adelaide, the University of Toronto, and the University of California, San Francisco, with support from the National Heart Foundation of Australia and the U.S. National Institutes of Health. Results were presented at the American Heart Association Scientific Sessions 2025 in New Orleans.
For Coffee Drinkers and Clinicians Alike
As global coffee culture continues to evolve — from third-wave cafés to specialty roasters and home-brewing enthusiasts — science is gradually catching up with what coffee lovers have long sensed: this beverage, when enjoyed responsibly, can be part of a healthy lifestyle.
The DECAF study doesn’t suggest that everyone should drink more coffee. But it does invite a thoughtful reevaluation of how we understand it — not as a vice to be limited, but as a natural, potentially protective companion to heart health.
Source: Caffeinated Coffee Consumption or Abstinence to Reduce Atrial Fibrillation: The DECAF Randomized Clinical Trial, JAMA (2025), DOI 10.1001/jama.2025.21056.
