“Doctors have always recommended that patients with problematic AFib minimise their coffee intake, but this trial suggests that coffee is not only safe but likely to be protective,” said first author of a new landmark study, Christopher X. Wong, PhD.
What is atrial fibrillation, and why should cyclists care?
Atrial fibrillation, often shortened to AFib, is the most common sustained heart rhythm disorder. It causes the heart to beat irregularly and often too fast, increasing the risk of stroke and heart failure.
AFib becomes more common with age, but endurance athletes are not immune. Long-term high training loads, structural changes to the heart, and episodes of dehydration can all increase susceptibility. Many experienced cyclists know someone who has had an unexpected AFib diagnosis after years of training healthily.
That is why caffeine has often been treated cautiously in this group.
The study that challenged the advice
The DECAF study, short for Does Eliminating Coffee Avoid Fibrillation, is the first randomised clinical trial to directly test whether caffeinated coffee affects AFib recurrence.
The researchers had 200 regular coffee drinkers with a history of AFib or atrial flutter take part in this clinical trial. All were scheduled for electrical cardioversion, a procedure that restores normal heart rhythm. After that, participants were randomly assigned to one of two groups for 6 months.
- One group drank at least 1 cup of caffeinated coffee or an espresso daily.
- The other group avoided all coffee and caffeinated beverages.
Coffee drinkers did better, not worse
By the end of the study, the coffee-drinking group had a 39% lower risk of AFib recurrence. That result runs directly against decades of conservative advice.
According to senior author Gregory Marcus, caffeine may help in several ways. Coffee consumption is associated with higher daily physical activity, which itself lowers AFib risk. Caffeine also has mild diuretic effects that may help reduce blood pressure. On top of that, coffee contains anti-inflammatory compounds that may positively influence heart tissue.
There is also a simpler explanation. People who drink coffee may replace less healthy drinks, such as sugary sodas, with coffee instead. Whatever the mechanism, the outcome was clear enough for the researchers to call the results astounding.
What this means for cyclists
This study does not mean that more coffee is always better or that caffeine cannot trigger symptoms in some individuals. Sensitivity still varies. But it does strongly suggest that moderate coffee intake is not inherently dangerous for heart rhythm, even in people already diagnosed with AFib. For cyclists, that is reassuring.
- If you enjoy coffee and tolerate caffeine well, there is currently no strong evidence that you need to cut it out purely for AFib prevention.
- If you have been diagnosed with AFib or heart rhythm symptoms, individual advice still matters. Talk to your cardiologist, especially if you notice palpitations linked to caffeine timing.
For healthy cyclists, moderate coffee intake appears compatible with both performance and heart health. And for many of us, that morning cup may be doing more good than harm.
