Coffee’s physiological effects are mixed, randomized trial shows

Reuters Health - 17/11/2021 - Drinking caffeinated coffee appears to have both beneficial and harmful acute effects in healthy adults, according to the first randomized trial to assess the real-time physiologic consequences of coffee consumption.

On coffee drinking days, participants were more physically active, yet slept less and had more premature ventricular contractions (PVCs) but no increase in atrial arrhythmias.

Results of the CRAVE study show that "the acute yet everyday physiologic effects of coffee are complex," principal investigator Dr. Gregory Marcus of the University of California, San Francisco, said at a press briefing at the American Heart Association scientific sessions, where he presented the findings.

In the CRAVE study, 100 adult volunteers (mean age, 38; 51% women) wore a continuous recording electrocardiography (ECG) device to track heart rhythm, a wrist-worn device to track physical activity and sleep, and a continuous glucose monitor to track blood sugar levels for two weeks. DNA saliva samples were obtained to assess genetic variants that may affect caffeine metabolism.

Participants were then randomly assigned to either avoid or consume coffee for no more than two consecutive days each for 14 consecutive days. Compliance was assessed "in multiple ways, each of which demonstrated excellent adherence to the randomization assignment," Dr. Marcus told the briefing.

"We found no increase in any atrial arrhythmias, and in fact, in per protocol analysis, there was less supraventricular tachycardia with more coffee consumption," he reported.

In contrast, coffee drinking was associated with a 54% increase in PVCs whether for randomized assignment or per protocol, and those who metabolized caffeine more quickly actually experienced a heightened response to PVCs with coffee exposure, Dr. Marcus noted.

Adults were more physically active on days randomly assigned to coffee drinking, but got less sleep on the nights following these days, he said.

Adults expected to metabolize caffeine more slowly demonstrated a more potent effect on sleep deprivation. There were no relationships with serum glucose.

"These data add to the growing evidence that those with supraventricular tachycardias or atrial contractions or at risk for those diseases should not necessarily avoid coffee. However, those prone to PVCs or ventricular arrhythmias may benefit from coffee abstinence, but genetic differences influence risks," Dr. Marcus said.

"Coffee may enhance overall physical activity, but this must be weighed against the risks associated with reduced sleep. And finally, those who metabolize caffeine more slowly are at greater risk of coffee-induced reductions in sleep," he added.

Offering perspective on the study and topic at the briefing, Dr. Sana Al-Khatib of Duke University Medical Center, in Durham, North Carolina, said, "I don't think I need to tell anyone about the need for more data on coffee consumption and cardiovascular health outcomes. This is a question that we receive quite frequently in clinical practice. There have been some studies published but the data are conflicting and it's not clear what to really tell patients at this time, so I commend Dr. Marcus and his team on taking on this important task."

Dr. Al-Khatib said CRAVE is a "well-conducted and informative trial" but it's important to look at the characteristics of the patients enrolled, which were mostly relatively young, healthy volunteers with no prior history of arrhythmias or cardiovascular disease, "so they're really not representative of the average patient that we see in clinical practice."

However, the trial is small and it will be "critically important" to see the results replicated by other groups, in other populations of patients and to look at hard outcomes during longer follow-up, she said.

The study had no commercial funding.

SOURCE: https://bit.ly/3kE1RL7 American Heart Association Scientific Sessions 2021, presented November 13, 2021.

By Megan Brooks



Posted on 17 November 20217 December 2021