Many people rely on a cup of coffee to set them up for the day, with new research suggesting the morning habit may ward off an irregular heart rhythm.
The health pros and cons of coffee have long been debated. Too many cappuccinos, espressos or mochas has been linked to arrhythmias – a generic term for heart rhythm problems that can raise the risk of cardiovascular complications.
With evidence being "poorly substantiated", scientists from the University of California in San Fransisco analysed the coffee consumption of more than 386,000 people over an average of four years.
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Results reveal every "additional" cup of coffee that the participants drank daily was linked to a 3% lower risk of arrhythmias – a small but statistically significant finding.
Coffee is one of the most popular drinks worldwide, but "has a reputation for causing or exacerbating arrhythmias", the scientists wrote in the journal JAMA Internal Medicine.
"Professional society guidelines" therefore often recommend people limit their intake. According to the California scientists, however, this is based on "assumed mechanisms and a small study from 1980".
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Coffee is said to be high in anti-inflammatory and antioxidant compounds, with studies suggesting the pick-me-up could ward off cancer, diabetes, Parkinson's disease and even premature death.
"When coffee avoidance is recommended, we may withhold a beneficial substance that improves quality of life and longevity," wrote the scientists.
To learn more, the scientists analysed participants – average age 56 – of the UK Biobank study. Over 4.5 years, nearly 17,000 of the participants developed an arrhythmia.
Drinking coffee every day was linked to a reduced risk. This remained the same after the scientists adjusted for other factors that can influence a person's arrhythmia risk, like their age, any pre-existing condition and other lifestyle habits.
Every additional cup of coffee was also found to lower the odds of atrial fibrillation – when the heart beats irregularly and abnormally fast, a common cause of a stroke – and a "flutter" – similar to atrial fibrillation but the rhythm is "less chaotic" – by 3%.
The results applied to all of the participants, not just those with genetic mutations that affect how they process caffeine.
In conclusion, the scientists wrote: "These data suggest common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted."
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More than 2 million people in the UK alone experience an arrhythmia every year.
Most people with an irregular heart beat can live a normal life. Nevertheless, atrial fibrillation raises a person's risk of a stroke by five times.
Certain arrhythmias also kill 100,000 people in the UK every year, deaths that could be avoidable if the condition was diagnosed earlier.
People can reduce their risk by drinking alcohol in moderation and maintaining a healthy weight. Medication, surgery and a pacemaker can also treat arrhythmias.
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