Coffee: new short-term side effects (both beneficial and harmful) just discovered thanks to smartwatches

Coffee: new short-term side effects (both beneficial and harmful) just discovered thanks to smartwatches

New research has found that coffee can have short-term physiological effects, both positive and negative

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New research carried out with the help of smartwatches has found that coffee can have short-term physiological effects, both positive and negative.

Uno study randomized analysis of coffee consumption among 100 volunteers for two weeks; finding potentially both beneficial and harmful short-term consequences. In fact, drinking coffee appears to have both beneficial and dangerous health effects, such as:

  • increased abnormal heart beat
  • increased physical activity
  • reduction in the duration of sleep.

Coffee is the most consumed beverage in the world, but its health effects remain uncertain. Although most long-term observational studies have suggested multiple benefits of coffee consumption, this is the first randomized study to analyze physiological and real-time consequences on coffee consumption.

A systematic review

The study was based on 100 adult volunteers, who had to wearing continuous recording ECG devices to monitor heart rhythm, devices worn on the wrist to monitor physical activity and sleep; and continuous blood glucose monitoring to check blood sugar levels for two weeks.

Participants had a mean age of 38, 51% were female, and 48% were white. The researchers also obtained DNA saliva samples, to evaluate genetic variants that can affect caffeine metabolism.

All patients were randomly asked to avoid or consume coffee for no more than two consecutive days each for 14 consecutive days. The coffee consumption was recorded in real time via a “timestamp button” on the ECG monitor, and researchers tracked trips to bars with geotracking. Additionally, they all completed daily questionnaires detailing how much coffee they had consumed each morning.

The results

THEanalysis found an important side effect, namely the coffee consumption was associated with a 54% increase in premature ventricular contractions, a type of abnormal heartbeat originating in the lower heart chambers that felt like a skipped heartbeat. 

On the contrary, instead, drinking more coffee was associated with fewer episodes of supraventricular tachycardia, an abnormally rapid heart rhythm arising from the upper heart chambers. But that's not all, as coffee consumption was constantly associated with more physical activity and less sleep. In particular:

  • participants who consumed coffee recorded more than 1.000 additional steps per day compared to the days they did not drink coffee.
  • On days attendees drank coffee, they slept 36 minutes less per night according to their Fitbit smartwatch devices.
  • drinking more than one coffee drink more than doubled the number of irregular heartbeats arising from the lower chambers of the heart.
  • each additional cup of coffee consumed was associated with nearly 600 more steps per day, and 18 fewer minutes of sleep per night.
  • there were no differences in the recorded glucose continuously measured when study participants consumed coffee versus that avoided.

More physical activity, which appears to be stimulated by coffee consumption, has numerous health benefits, such as reduced risk of type 2 diabetes and various cancers, and is associated with increased longevity. On the other hand, however, the sleep reduction is associated with a variety of psychiatric, neurological and cardiovascular problems. In addition, more frequent abnormal heartbeats from the upper heart chambers affect the risk of atrial fibrillation, while more frequent abnormal heartbeats from the lower chambers, or ventricles, increase the risk of heart failure.

Study participants with genetic variants associated with a faster metabolism of caffeine showed more abnormal heartbeats originating from the ventricles, when more coffee was consumed. The slower an individual metabolizes caffeine based on their genetics, the more sleep they lose when drinking caffeine. All these results highlight the complex relationship between coffee and health, and the research aims to understand this relationship in more depth.

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Photos: American Heart Association

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