Caffeine appears to do the opposite of what you might think when it comes to the heart. Scientists have found that a cup of coffee a day actually protects the heart from atrial fibrillation – a condition that can lead to stroke and heart failure.
University of Adelaide and University of California, San Francisco (UCSF) researchers have led a randomized clinical trial of 200 adults from Australia, the US and Canada with AF to test coffee's impact on this irregular heartbeat condition. Over six months, 100 of the participants consumed at least one cup of coffee or an espresso shot each day, while the other 100 abstained from all types of coffee and caffeine. They were constantly monitored and had any AF events confirmed by electrocadiograms and clinicians.
And what they found surprised even the medical professionals involved in the world-first trial.
“The results were astounding," said first author Professor Christopher X. Wong from the University of Adelaide and Royal Adelaide Hospital. "In contrast to conventional wisdom, we found the coffee drinkers experienced a significant reduction in AF compared to those who avoided coffee and caffeine.
“This is surprising as it goes against the common assumption by doctors and patients that coffee worsens heart rhythm disorders such as AF," he added. "Doctors have always recommended patients with problematic AF minimize their coffee intake, but this trial suggests that coffee is not only safe but likely to be protective.”
AF is an irregular heart rhythm that begins in the heart's upper chambers (atria), preventing blood from pumping around the body normally. It can cause dizziness, fatigue and palpitations, but can become more serious and lead to heart failure, stroke and even death. More than 10 million US adults have the condition long-term, putting them at greater risk of high blood pressure, obesity and other heart diseases. And caffeine is a constant on lists of things that experts recommend to avoid.
In the DECAF (Does Eliminating Coffee Avoid Fibrillation) trial, the researchers found that caffeine resulted in a 39% lower risk of recurrent AF events, compared to those who abstained – and they have a few theories as to why this might be the case.
“Coffee increases physical activity which is known to reduce AF," said senior author Professor Gregory Marcus from the Division of Cardiology at UCSF. "Caffeine is also a diuretic which could potentially reduce blood pressure and in turn lessen AF risk. Several other ingredients in coffee also have anti-inflammatory properties that could have positive effects."
According to the US National Coffee Association, around two-thirds of adults drink at least one cup a day, and scientists have long been curious about its potential benefits (and harms). In recent years, studies have been conducted to see if coffee can help the brain and cognitive functioning, healthy aging and, of course, the heart.
“The number of people with AF is rising and the risk of developing the condition increases with age," said Marcus. "As a result, there’s certainly a lot of interest in ways to reduce the burden of the condition. Our study provides more clarity on the effect of caffeinated coffee on AF patients and should change the medical advice we give to patients."
As mentioned, coffee is implicated as a trigger for AF – which may need to be revised based on the results of this large trial. However, the condition is still predominantly thought to be caused by lifestyle choices including diet, but can also be the result of obesity, sleep apnea, diabetes and a family history of AF.
While the researchers note that coffee isn't a cure-all for AF, it could actually provide some benefits – and at the very least shouldn't be blacklisted or be thought to trigger the condition.
“Based on these results, coffee-drinking patients with AF can safely continue to enjoy their coffee," said Wong. "Furthermore, it may be worth investigating whether AF patients who don’t drink coffee should actually consider starting."
The research was published in The Journal of the American Medical Association. (Eds: Link Monday off embargo)
Source: The University of Adelaide via Scimex
