Chronic caffeine consumption – defined as the intake of any caffeinated drinks five days per week for more than one year – of 400 mg daily was shown to significantly impact the autonomic nervous system, raising the heart rate and blood pressure over time.

“Regular caffeine consumption could disturb the parasympathetic system, leading to elevated blood pressure and heart rates,” said lead author Nency Kagathara, MBBS, from Zydus Medical College and Hospital in Dahod, Gujarat.

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

Chronic high caffeine consumption linked to raised blood pressure

The study, which was presented last month at ACC Asia 2024 in New Delhi, investigated the cardiovascular effects of drinks including tea, coffee, and aerated beverages such as Coca-Cola, Pepsi, Red Bull, Sting, and Monster.

Participants – a randomised group of 92 normotensive and healthy individuals aged between 18 and 45 years – had their blood pressure and pulse measured and underwent a three-minute step test. Blood pressure and heart rates were measured one minute and five minutes after the test.

Almost one in five (19.6%) consumed more than 400 mg of caffeine every day, which translates to about four cups of coffee, 10 cans of soft drinks, or two energy drinks.

Caffeine consumption of 400 mg daily was shown to significantly impact the autonomic nervous system, while participants who consumed more than 600 mg per day had significantly elevated heart rates and blood pressure after five minutes of rest following the step test.

The highest daily intakes were observed in people who were female, employed in business and management roles, and living in urban areas.

Mixed findings on heart disease risk link in healthy individuals

High blood pressure, or hypertension, is associated with an increased risk of coronary artery disease, heart failure, chronic kidney disease, and dementia. The condition weakens the heart over time and is a leading risk factor for heart disease.

Previous research has suggested that high caffeine consumption – defined as drinking two or more cups of coffee a day – may double the risk of death from cardiovascular disease in people with severely high blood pressure.

However, the increased risk did not translate to participants with lower blood pressure measurements, and findings among healthy people are inconsistent.

One UK Biobank study suggested that coffee consumption may in fact be linked with reduced heart disease risk, while other studies show that coffee drinkers have a much lower risk of dementia, Alzheimer’s disease, and Parkinson’s disease in old age.

Hypertension: A leading risk factor for heart disease

Globally, it is estimated that 1.28 billion adults have hypertension, according to the World Health Organization. As many as 46% of sufferers are unaware that they have the condition, and just 42% are diagnosed and treated for it.

In Europe, joint guidance from the European Society of Cardiology (ESC) and European Society of Hypertension (ESH) defines hypertension as a blood pressure reading of 140/90 mm Hg or higher; in the US, the cut-off point is lower, at 130/80 mm Hg.

Low- and middle-income countries carry a significant disease burden, accounting for two-thirds of cases, WHO statistics suggest.

In addition to caffeine intake, there are several factors that could contribute to high blood pressure, such as alcohol consumption, smoking, age, family medical history, and salt consumption.

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

“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,” said Kagathara. “Increasing awareness of these risks is vital to improve heart health for all.”