Having up to five cups of coffee a day may be linked to a lower risk of heart disease and stroke, new research suggests — though experts caution that pushing caffeine intake too high could be harmful.
The study, published in the Journal of the American Heart Association, adds to growing evidence that black coffee may offer meaningful benefits for cardiovascular health.
Researchers in the US reported that drinking coffee plain — without sugar, syrups, flavourings or milk — was associated with reduced odds of type 2 diabetes, heart disease, stroke, heart failure and abnormal heart rhythms.
Scientists believe some of coffee’s potential protective power may come from polyphenols, naturally occurring anti-inflammatory compounds found in coffee beans.
These antioxidant-rich substances can help defend the body against environmental damage, support healthier blood vessel function and reduce inflammation — a process tied to serious illnesses, including cancer.
Caffeine itself may also play a role in these health effects, the researchers noted, although its impact can differ widely depending on the individual.
But too much caffeine can put strain on the heart, potentially causing sharp rises in blood pressure, irregular heartbeats and, in rare cases, cardiac arrest even among otherwise healthy adults.
“Caffeine consumed in coffee is a key part of daily life for millions of people,” said Dr Gregory Marcus, chief of cardiology for research at the University of California.
Drinking five cups of coffee a day could significantly slash your risk of heart failure
‘In our review of the most recent research, for most adults, intake of up to 400mg of caffeine a day [around five cups] without added sugars is safe and does not increase cardiovascular risk.
‘However high doses of caffeine, such as those found in energy drinks including energy shots, may have harmful effects on the heart and should be avoided.’
The research marks a major shift by comparing how coffee and synthetic caffeine affect blood pressure, cholesterol, diabetes risk and cardiovascular health.
The researchers found that drinking around five cups of coffee a day seemed to decrease the risk of high blood pressure, a major killer that affects around one in three Britons.
But drinking one to three cups was found to spike blood pressure levels, which can increase the likelihood of heart attack and stroke.
Daily coffee consumption was also linked with a lower risk of atrial fibrillation – a condition that causes heart palpitations, as well as potentially heart failure, blood clots and strokes.
It is a common assumption that consuming caffeinated coffee can trigger an elevated heart rate.
However, a 2025 study found that 200 patients with persistent irregular heartbeats had a significantly lower risk of the condition recurring if they drank coffee.
Drinking five cups of coffee a day was also associated with a 30 per cent lower risk of developing type 2 diabetes.
Another study, using data from the UK biobank, found that those who drink five cups a day are less likely to develop heart disease than non-drinkers.
A similar pattern was found for stroke risk: One study found that those who drink around four cups a day can reduce their risk by up to 21 per cent.
However, the researchers stressed there is ‘no one-size-fits-all strategy for safe caffeine consumption’, with high doses of caffeine posing a serious health risk to otherwise healthy individuals.
Adding sugar, flavoured syrups, milk and/or cream to coffee was also found to reduce its potential health benefits, with coffee’s heart-healthy benefits applying strictly to paper-filtered or instant coffee.
Dr Marcus explained: ‘Although research suggests that caffeine consumption may be associated with certain cardiovascular benefits for some… people can respond very differently to caffeine based on various factors, such as age, medications, underlying health conditions, genetics and how quickly their bodies metabolise it.
‘What may be a reasonable amount for one person could cause unwanted effects, such as heart palpitations, anxiety or sleep disruption, in another.’
Unfiltered options, such as French press, were found to increase levels of so-called bad cholesterol that can build up in the arteries over time, increasing the risk of a clot.
Crucially, these heart-health benefits do not apply to highly concentrated synthetic caffeine products such as energy drinks, the researchers warn.
It comes as children under 16 will be banned from buying high-caffeine energy drinks in England from April next year.
Drinks containing more than 150mg of caffeine per litre will be illegal to sell to children and young teenagers in shops, vending machines and online under the new regulations.
Lower-caffeine soft drinks such as Diet Coke, as well as tea and coffee will not be affected.
However drinks including Red Bull, Monster and Prime will all breach the limit – which has been set to reduce obesity levels in children and mitigate increasing anxiety levels, poor concentration and falling grades.
Around 100,000 children in England are thought to consume energy drinks every day, with some popular brands containing more caffeine than two cups of coffee.
