A new study finds that drinking up to three coffee cups (or other caffeinated beverages) can decrease the risk of arrhythmias.

Image credits: Jonathan McIntosh / Wikipedia.

Arrhythmias, or abnormal heart rhythms, is an umbrella term for a group of conditions where the heartbeat is irregular — too slow, too fast, or just uneven. Oftentimes, these arrhythmias are harmless and go unreported — but they significantly increase the risk of sudden cardiac arrest. Doctors typically advise patients suffering from such heart problems to avoid caffeinated drinks, but is that really a good thing? The authors of a new study claim that that perception is based more on anecdote rather than actual scientific evidence.

“There is a public perception, often based on anecdotal experience, that caffeine is a common acute trigger for heart rhythm problems,” said Peter Kistler, MBBS, PhD, director of electrophysiology at Alfred Hospital and Baker Heart and Diabetes Institute, and the review’s lead author. “Our extensive review of the medical literature suggests this is not the case.”

Kistler and colleagues analyzed multiple population-based studies to determine if there is an association between arrhythmias (particularly atrial fibrillation, or AFib), and caffeine intake. They did find a correlation — but it wasn’t what you’d expect. Instead, studies consistently showed that doses up to 500 mg daily (equivalent to six cups of coffee) did not increase the severity or rate of VAs. Caffeine doses up to 250 mg daily were actually correlated with lower rates of AFib. In other words, drinking up to three coffees a day seems to protect your heart from arrhythmias. For instance, one of the studies they analyzed featured 228,465 participants and showed AFib frequency decreasing by 6 percent in regular coffee drinkers. A further analysis of 115,993 patients showed a 13 percent risk reduction.

“Caffeinated beverages such as coffee and tea may have long term anti-arrhythmic properties mediated by antioxidant effects and antagonism of adenosine,” Kistler said. “In numerous population-based studies, patients who regularly consume coffee and tea at moderate levels have a lower lifetime risk of developing heart rhythm problems and possibly improved survival.”

However, authors stress that energy drinks should be avoided by anyone with a pre-existing heart condition. They also point out that there may be significant personal differences between different people.

It’s not exactly clear why this happens, but researchers propose the following mechanism. Caffeine acts as a stimulant to the central nervous system, and once it’s inside our bodies, it blocks the effects of adenosine, a chemical that facilitates AFib.

Coffee remains a controversial topic, with several studies reporting both positive and negative effects. With over 2 billion cups being consumed each day, coffee has become a massive worldwide industry, and even something of a foodie fixation.

Journal Reference: Aleksandr Voskoboinik et al. Caffeine and Arrhythmias : Time to Grind the Data. doi.org/10.1016/j.jacep.2018.01.012