If the thought of that first cup of coffee in the morning sets your heart aflutter, a new report has good news for you. In the largest study of its kind, an investigation by the University of California San Francisco has found no evidence that moderate coffee consumption can cause cardiac arrhythmia.
Heart arrhythmias occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow or irregularly. Heart arrhythmias might feel like a fluttering or racing heart.
In fact, each additional daily cup of coffee consumed among several hundred thousand individuals was associated with a 3% lower risk of any arrhythmia occurring, including atrial fibrillation, premature ventricular contractions or other common heart conditions, the researchers report. The study included a four-year follow up.
“Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias,” said senior and corresponding author Gregory Marcus, MD, professor of medicine in the Division of Cardiology at UCSF.
“But we found no evidence that caffeine consumption leads to a greater risk of arrhythmias,” said Marcus, who specializes in the treatment of arrhythmias. “Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted.”
A February analysis by the American Heart Association of three major studies found drinking one or more cups of black coffee a day lowered the risk of heart failure on a long-term basis. Other studies have found that coffee consumption may have anti-inflammatory benefits and is associated with reduced risks of cancer, diabetes, Parkinson’s and other diseases.
In the new study, UCSF scientists analyzed data on 386,258 coffee drinkers via the community-based UK Biobank, a prospective study of participants in England’s National Health Services. It was an unprecedented sample size for this type of inquiry.
“Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption,” Marcus said. “But our study found no evidence that consuming caffeinated beverages increased the risk of arrhythmia. Coffee’s antioxidant and anti-inflammatory properties may play a role, and some properties of caffeine could be protective against some arrhythmias.”
The full study was published online Monday in JAMA Internal Medicine.
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