A glass of wine a day may be worse for your heart than binge drinking, research suggests.
Scientists from Korea University looked at the drinking habits of more than nine million people over eight years.
They found those who drank every day were 41% more likely to develop atrial fibrillation (AF).
AF occurs when abnormal electrical impulses cause the heart to beat irregularly and unusually fast. The common condition can lead to blood clots and raises the risk of stroke by four-to-five times.
Perhaps surprisingly, no link was found between binge drinking and AF, the results show.
Alcohol is known to affect sleep, with a lack of shut eye being associated with AF. The scientists warn drinking every day may cause the damaging effects of beer, wine and spirits to build up over time.
“Our study suggests drinking less often may be important to protect against AF,” study author Dr Jong-Il Choi said.
“AF is a disease with multiple dreadful complications and significantly impaired quality of life. Preventing AF itself, rather than its complications, should be our first priority.
“Alcohol consumption is probably the most easily modifiable risk factor. To prevent new-onset AF, both the frequency and weekly amount of alcohol consumption should be reduced.”
AF is a common condition, with 1.2 million people being affected in the UK, Stroke Association statistics show.
In the US, up to 6.1 million are thought to have the condition, according to the Centers for Disease Control and Prevention.
AF occurs when the electrical impulses that ‘tell’ the heart to contract get out of sync, triggering palpitations.
Excessive alcohol consumption is a recognised risk factor, according to the British Heart Foundation.
Past research found the risk of AF increases by 8% for every drink consumed over a week. However, it was unclear whether the total amount of alcohol consumed or the number of drinking sessions was to blame.
To learn more, the Korean scientists looked at 9.7 million healthy adults. The participants took part in a nationwide health check-up in 2009, which included a questionnaire on their alcohol consumption.
In 2017, they were called back to check for signs of AF.
Results - published in the journal EP Europace - show those who drank every day were more likely to develop an irregular heart beat than those who only consumed alcohol twice over a week. No link was found between binge drinking and AF.
For every gram of alcohol drunk a week, the participants’ risk of “heart flutter” rose by 2%.
Compared to mild drinkers, those who consumed high amounts of wine, beer or spirits were 21.5% more at risk, the results show. Moderate consumption rose the odds by 7.7%. It is unclear how high or moderate drinking was defined.
In better news, the findings also show those who drank just once a week were 7% less likely to have AF than mild drinkers.
But mild drinkers were 8.6% less at risk than those who abstained from alcohol completely.
The protective effects of alcohol are controversial. When drunk in moderation, antioxidants in red wine have been shown to boost ‘good’ cholesterol. Too much, however, can weaken the heart’s muscle, preventing it from pumping effectively.
The results remained true even after the scientists accounted for the participants’ sex and age. AF becomes more common in old age, with most sufferers being over 65. Men are more likely to be affected than women, according to the NHS.
It is unclear exactly why this occurs, however, insomnia may be to blame.
“Repeated episodes of AF triggered by alcohol may lead to overt disease,” Dr Choi said. “In addition, drinking can provoke sleep disturbance which is a known risk factor for AF.”