Some who have been told to steer clear of caffeine might get a green light now thanks to this "game changing" research.
For those with cardiovascular conditions, conventional wisdom has long been to limit coffee intake. The caffeine present in coffee acts as a stimulant in our bodies, and it can increase heart rate and blood pressure as well as produce extra heartbeats, according to the American Medical Association. But a new study is challenging that notion for a particular set of patients.
The study—cleverly named the DECAF (Does Eliminating Coffee Avoid Fibrillation) trial—was conducted by a team of heart health experts from the University of California, San Francisco (UCSF) and Australia’s University of Adelaide. The results, published in the Journal of the American Medical Association Network in November 2025, found that drinking one cup of coffee a day actually lowered the risk of atrial fibrillation (also known as AFib) by 39%.
Researchers conducted a randomized trial of 200 participants who were both regular coffee drinkers and had persistent AFib or a related condition known as atrial flutter, another type of irregular heart rhythm that’s too fast, along with a history of AFib. All of the trial participants were scheduled to undergo electrical cardioversion, a procedure that uses a controlled electrical shock to help regulate heart rhythm. Half of the participants were assigned to drink at least one cup of caffeinated coffee or an espresso shot a day, while the other group was directed to avoid all coffee and other caffeinated drinks for at least six months.
The coffee drinkers saw a 39% lower risk of AFib recurrence at the end of the study, which greatly surprised the researchers—though there is a possible explanation, said senior author Gregory Marcus, MD, MAS in a University of Adelaide news release. “Coffee increases physical activity which is known to reduce [atrial fibrillation]. Caffeine is also a diuretic which could potentially reduce blood pressure and in turn lessen [atrial fibrillation] risk,” said Dr. Marcus, who is also a associate chief of cardiology for research UCSF Health.
AFib is an irregular heart rhythm that starts in the heart’s upper chambers, or atria. It’s caused when there is an interruption in the heart’s normal electrical signals that tell the atria to contract and therefore pump blood to the heart’s lower chambers, the ventricles. Unusual electrical signals from the atria can interrupt this process, according to the National Heart, Lung, and Blood Institute, which can cause the atria to contract irregularly, making it difficult for the upper and lower chambers of the heart to work together to effectively pump blood throughout the body.
Common symptoms of AFib include:
- Rapid or irregular heartbeat
- Fluttering or thumping in the chest
- Dizziness
- Shortness of breath or anxiety
- Fatigue
- Sweating
- Chest pain or pressure
- Faintness or confusion
But the study offers a new sense of excitement—for both researchers and heart patients. “The results were astounding,” said first author and cardiologist Christopher X. Wong, MBBS, MPH, PhD. “Doctors have always recommended that patients with problematic AFib minimize their coffee intake, but this trial suggests that coffee is not only safe but likely to be protective.”
The researchers also theorized that, in addition to coffee’s potential anti-inflammatory properties, the coffee-drinking trial participants may have swapped less healthy drinks like sugary soda for coffee.
For daily wellness updates, subscribe to The Healthy newsletter and follow The Healthy on Facebook and Instagram. Keep reading:
- New Study: Walking Like This Cut Rates of Heart Attacks, Stroke, and Death by More Than 60%
- New Study: Just This Much Exercise Could Lower Risk of Death from AFib
- 5 Surprising AFib Triggers, from a Cardiologist
- Skipping Exercise for This Long Could Have a Major Impact on Your Heart Health, Says New Study
