Too much coffee can be a latte for the heart to handle, with a new study linking over 400 milligrams of caffeine a day — roughly a venti-size coffee at Starbucks — to an increased risk of cardiovascular disease even for otherwise healthy people.
“Regular caffeine consumption could disturb the parasympathetic system, leading to elevated blood pressure and heart rates,” explained lead study author Nency Kagathara, of Zydus Medical College and Hospital in Dahod, India.
Kagathara’s team measured the blood pressure and heart rates of 92 healthy adults after they performed a three-minute step test. Participants were 18 to 45 years old with normal blood pressure at the start of the experiments.
Nearly 20% of participants consumed more than 400 mg of caffeine every day, which is the equivalent of about four cups of coffee, 10 cans of soda or two energy drinks.
Chronic daily consumption of 400 mg was found to raise heart rate and blood pressure over time. The study findings were presented Thursday at the American College of Cardiology conference in Delhi, India.
The US Food and Drug Administration has said that 400 mg of caffeine a day is “not generally associated with dangerous, negative effects,” while acknowledging that some people are more sensitive to caffeine and it can be metabolized at different rates.
The Mayo Clinic says up to 400 mg of caffeine “appears to be safe for most healthy adults.”
Caffeine is a stimulant that can promote the production of the stress hormones noradrenaline and epinephrine, increasing heart rate and raising blood pressure by narrowing blood vessels.
But it’s also been found to elevate mood and possibly lower the risk of certain cancers, among other benefits.
Kagathara reported that urban women in business and management roles had the highest daily caffeine intake in her study.
Those who consumed more than 600 mg of caffeine a day had significantly elevated heart rates and blood pressure after five minutes of rest following the step test.
“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,” Kagathara said. “Increasing awareness of these risks is vital to improve heart health for all.”
Hypertension is another name for high blood pressure, a condition tied to a higher risk of coronary artery disease, heart failure, chronic kidney disease and dementia.
Experts suggest exercising regularly and following a nutritious diet to lower blood pressure. Medication may be prescribed if weight loss, dietary changes and exercise are unsuccessful.
Dr. Benjamin Hirsh, director of preventative cardiology at North Shore University Hospital, called the new study results “compelling.”
“The study findings are and should make people aware that coffee to excess can cause risk to the heart over time, causing hypertension and arrhythmias,” said Hirsh, who was not involved with the research. “Over-reliance of caffeine may help productivity, but health always should be at the fore.”
