One Small Cup of Coffee for Man, One Giant Pot for Mankind?

Volume 25, Issue 4

Coffee is one of the most ubiquitously consumed drinks across the world. Indeed, yours truly is an ardent consumer of all things caffeine, including a couple cups of my favorite morning brew each day.

In addition to being a stimulant, coffee is full of antioxidants and may possess anti-inflammatory properties that confer various health benefits. Population-based studies have demonstrated consistently that coffee drinkers have reduced mortality rates, and epidemiologic studies show coffee drinkers have a lower risk of diabetes than persons who avoid coffee. 

Despite these benefits, there are concerns that coffee consumption can trigger mild arrhythmias like premature atrial contractions, which are linked to a greater lifetime risk of developing more serious arrhythmias like atrial fibrillation. Robust evidence on the pro-arrhythmic effects of coffee does not exist. 

In this week’s issue of Talking Therapeutics, we look at a study published in The New England Journal of Medicine this week which investigates the short-term effects of coffee consumption in healthy, ambulatory adults. 

Point 1: Coffee Has Myriad Short-term Physiologic Effects

In this new paper, ambulatory adults were fitted with remote electrophysiologic monitoring and randomized to either abstain or consume coffee via daily text message alerts. The participants were tracked on their phones to ensure they were visiting coffee shops on the days randomized to consume caffeine. 

Short-term coffee consumption did not significantly increase the number of premature atrial contractions that study participants experienced (rate ratio, 1.09; 95% confidence interval [CI], 0.98 to 1.20; P = .10), but did slightly increase the number of premature ventricular contractions (rate ratio, 1.51; 95% CI, 1.18 to 1.94). Compared to coffee avoiders, coffee consumers took about 1000 more steps per day (95% CI, 441 to 1675) but slept about 30 fewer minutes per night (95% CI, 25 to 47). Continuous glucose monitoring did not reveal any significant differences between the days in which coffee was consumed vs avoided (mean difference, -0.41; 95% CI, -5.42 to 4.60).

Point 2: Health Benefits of Coffee Remained Undefined

These results are reassuring in the sense that there was no signal for increased pro-arrhythmia with acute coffee consumption. While the increase in number of steps taken may help to explain the lower mortality seen in population-based studies, there are too many factors that influence overall mortality to draw firm conclusions. The benefits of increasing step count must be weighed against the loss of sleep, which can have negative health implications. 

Given the similar blood glucose levels seen in both coffee drinkers and non-coffee drinkers, the lower rates of diabetes observed in coffee drinkers remains unexplained.