How much coffee is safe to drink?

Drinking four or more cups of coffee a day could raise the risk of a heart attack or stroke, a new study has warned.

Researchers found that consuming over 400 milligrams of caffeine on most days of the week could increase the susceptibility of otherwise healthy people to cardiovascular disease.

Around one in five participants in the Indian study (19.6%) consumed that much caffeine every day, which translates to around four cups of coffee, 10 cans of fizzy pop or two energy drinks.

The research suggested such "chronic" caffeine consumption could significantly impact the autonomic nervous system, raising heart rate and blood pressure over time.

High blood pressure, also known as hypertension, is associated with an increased risk of coronary artery disease, heart failure, chronic kidney disease, and dementia.

Hypertension weakens the heart over time and is a leading risk factor for heart disease.

Tea and coffee, which both contain caffeine, are an integral part of the morning routine for people all around the world, but scientists say they can be "harmful" when consumed in excess.

Commenting on the findings study lead author Nency Kagathara, from Zydus Medical College and Hospital in Dahod, India, says: "Regular caffeine consumption could disturb the parasympathetic system, leading to elevated blood pressure and heart rates.

"Our study sought to determine the effects of chronic caffeine consumption on heart health, specifically the recovery of heart rate and blood pressure,” she says.

• Chronic caffeine consumption was defined as the intake of any caffeinated drinks five days per week for more than one year.

The study focused on tea, coffee and fizzy drinks such as Coke, Pepsi, Redbull, Monster and Sting.

The research team evaluated a group of 92 healthy people aged from 18 to 45. All the participants had their blood pressure and pulse measured and underwent a three-minute step test.

Blood pressure and heart rates were measured 60 seconds and five minutes after the test. Each participant’s daily caffeine intake was also recorded.

The findings showed that the highest daily caffeine intakes were observed in participants who were female, employed in business and management roles, and living in urban areas.

Those who consumed the highest amounts, chronic caffeine consumption of more than 600 mg of caffeine per day, had "significantly" elevated heart rates and blood pressure after five minutes of rest following the step test

Ms Kagathara continues: "Due to its effect on the autonomic nervous system, regular caffeine consumption could put otherwise healthy individuals at risk of hypertension and other cardiovascular events.

"Increasing awareness of these risks is vital to improve heart health for all."

Other factors that could contribute to high blood pressure include alcohol consumption, smoking, age, family medical history, and salt consumption.

But increasing physical activity, following a nutritious diet and other lifestyle changes could help lower blood pressure and reduce the risk of heart disease.

The findings of the new study are due to be presented at the American College of Cardiology (ACC) Asia 2024 conference in Delhi, India and as such they should be considered preliminary until published in a peer-reviewed journal.

How much coffee is it safe to drink?

While there are plenty of perceived benefits of coffee, experts are also keen to stress it isn't a a magic bullet and should be enjoyed in moderation.

"It’s important to acknowledge that coffee, in moderation, can offer certain health benefits due to its antioxidant properties and potential to improve mental alertness," explains Dr Joseph Ambani. "However, as with many things, moderation is key.

"The recent study highlighting the increased risk of heart attack with the consumption of four or more cups of coffee per day is a useful reminder that excessive caffeine intake can have adverse effects on cardiovascular health," Dr Ambani continues.

"Caffeine is a stimulant that can raise blood pressure and heart rate, which, over time, may contribute to heart-related issues, especially in individuals with pre-existing conditions such as hypertension or arrhythmias."

So how much is too much?

According to the European Food Safety Authority’s review of caffeine safety, a safe coffee intake can be defined as three to five cups per day, up to 400mg per day, while the NHS says more than 600mg/day can lead to anxiety, sleeplessness, agitation, palpitations, diarrhoea and restlessness.

It's also worth considering the size of the cup of coffee you're drinking and the type. According to Coffee Code UK, there are a number of things that affect how much caffeine there is in a cup of coffee, including the type of coffee used, brewing method and roast level, but as a guide they anticipate there to be anywhere between 63mg to 100mg in a single cup, more in a bigger cup.

Remember also that caffeine isn't just found in coffee, but tea, fizzy drinks, chocolate and certain energy drinks, so remember to monitor your total intake.

"For most people, drinking one to three cups of coffee per day is generally considered safe and might even be beneficial," Dr Ambani continues.

"However, I often advise my patients to be mindful of their total caffeine intake, which includes not just coffee but also tea, energy drinks, and certain medications. The safe upper limit is usually around 400 milligrams of caffeine per day, which equates to about four cups of brewed coffee. But individual tolerance can vary significantly."

As Dr Ambani points out some individuals are more sensitive to caffeine and may experience adverse effects even at lower levels of consumption. Symptoms such as palpitations, anxiety, and insomnia can be early indicators that one’s caffeine intake might need to be reduced.

"While moderate coffee consumption is generally safe for most people, it’s crucial to listen to your body and adjust your intake based on your health status and how you personally react to caffeine," Dr Ambani continues.

"For those with underlying heart conditions or those who are particularly sensitive to caffeine, I would recommend limiting coffee to one or two cups per day or exploring decaffeinated options."

Additional reporting SWNS.

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