Drinking four or more cups of coffee a day, or two energy drinks, can raise the risk of a heart attack or stroke, warns a new study. 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. Such “chronic” caffeine consumption was shown to 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 they can be “harmful” when enjoyed in excess, say scientists.
Study lead author Nency Kagathara, of Zydus Medical College and Hospital in Dahod, India, said: “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.”
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 said: “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.”
She added: “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.