The study by an American university found that energy drinks can trigger abnormal heart rhythm and a rise in blood pressure, leading to an increased risk of stroke and sudden cardiac death.
“Our findings suggest certain energy drinks may increase the risk of having an abnormal heart rhythm when consumed in high volumes,” said Sachin Shah, associate professor of pharmacy practice at the University of the Pacific.
The study involved 27 healthy volunteers aged 18 to 40 who either drank two cans of an energy drink, an equivalent volume of a drink containing panax ginseng - an ingredient in the energy drink - or a placebo beverage once a day, every six days, for three weeks.
The researchers measured subjects’ heart rhythm and blood pressure before the drinks were consumed and four times during the six hours immediately afterwards.
The volunteers who consumed the energy drink experienced a statistically significant increase in a marker of abnormal heart rhythm risk known as the QTc interval. These volunteers also experienced a slight rise in blood pressure, but the ginseng and placebo groups showed no rises in QTc interval or blood pressure.
Prof Roderick King, a biochemist at Leeds Beckett University who specialises in human metabolism and its relationship with health, exercise and nutrition, said the danger of excessive use of caffeine were already well documented.
“Caffeine is a key ingredient of many energy drinks and there is an established link between high intake and heart palpitations and mood swings,” said Prof King.
“For most people, energy drinks are no more dangerous than coffee: the problems come with excessive use.
“The research group I run at Leeds Beckett has a specific interest in the effects of carbohydrates and caffeine, and the benefits and dangers of sports drinks.
“We are examining whether there is a measurable performance edge, and what the implications for health are.
“I don’t think energy drinks are particularly dangerous in themselves: the danger arises when people use them excessively and overdose on them by general consumption.
“When consumed as part of a healthy, balanced diet they are generally very safe.”