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Coffee is one of the most popular beverages consumed globally and is certainly the most popular beverage at Coyne Medical. Its health effects have been the subject of numerous observational studies. However, the majority of these studies are prone to confounding by other factors, and there is a lack of randomised controlled trials examining the acute (short-term) effects of coffee consumption. The Coffee and Real-time Atrial and Ventricular Ectopy (CRAVE) trial was designed to address this gap in knowledge.

The CRAVE trial involved 100 adults fitted with wearable monitors, including an electrocardiogram-recording device, an accelerometer, and a continuous glucose monitor. Participants were randomised via daily text messages to either consume all the caffeinated coffee they wanted or avoid all caffeine. Adherence to the randomisation assignment was assessed using various methods, including a real-time participant activation button on the ECG monitor to timestamp every cup of coffee.

The primary outcome of the study was premature atrial contractions (PACs), which are a potent harbinger of atrial fibrillation risk. PACs are premature heartbeats that arise from the atria, the upper chambers of the heart. Atrial fibrillation is an important risk factor for stroke. The study found that consumption of caffeinated coffee was not associated with an increased frequency of PACs. However, days randomised to coffee were associated with 51% more premature ventricular contractions (PVCs), which are associated with an increased risk of subsequent heart failure in older adults. PVCs are premature beats that arise from the lower chambers of the heart. Those who consumed more than two cups of coffee experienced more than a doubling of their PVCs. 

The study also found that on days randomised to coffee, participants took about 1000 more steps but experienced more than a half-hour less sleep. Despite epidemiological evidence that coffee consumers experience a lower risk of developing diabetes, no differences in serum glucose were observed in any of the analyses comparing exposure to coffee with caffeine avoidance.

The study revealed complex acute effects of coffee related to several physiological processes fundamental to overall health, which manifest differently between individuals. The findings suggest that those concerned about PVC frequency and the associated risk of subsequent heart failure might consider reducing or eliminating coffee. These would be people who are known to have these types of abnormal heartbeats and are usually, over 65 years of age. However, those struggling with insomnia should incorporate this study data to motivate at least a trial of strict coffee avoidance to determine if it might benefit their sleep.

The CRAVE trial provides valuable insights into the acute effects of coffee consumption and highlights the importance of personalised lifestyle goals. The multidimensional effects of caffeinated coffee consumption should be taken into consideration when making decisions about coffee consumption, and individuals should consider their own health concerns when determining their coffee intake. Taken overall, the study provides important information that can be used to facilitate improved shared decision-making and promote longevity and healthspan.

Dr Hugh Coyne 

Private GP 

Parsons Green