Drinking sugary caffeinated energy drinks is more dangerous than caffeine alone, research suggests.
A study found consuming four cans of energy drink resulted in abnormal changes in blood pressure and heart rhythm within two hours.
Researchers found drinking 32 fluid ounces – just under a litre – of an unnamed but commercially-available energy drink resulted in profound changes to the heart’s electrical activity and blood pressure.
The drink was packed with 108g of sugar – roughly 27 teaspoons – and 320mg of caffeine, close to the daily recommended daily limit, along with other ‘natural’ substances such as taurine, ginseng and carnitine.
The impact on the heart was significantly greater than drinking the same volume of a drink with the equivalent caffeine content but no sugar or added substances, the researchers found.
Researcher Dr Emily Fletcher, of the US Air Force Medical Centre in Travis, California, said: ‘We decided to study energy drinks’ potential heart health impact because previous research has shown 75 per cent of the base’s military personnel have consumed an energy drink.’
Her team, whose findings were published in the Journal of the American Heart Association, said there are more than 500 types of energy drinks on the market, and a spike in A&E visits linked to the products has prompted questions about their safety.
They tracked 18 young participants were randomly divided into two groups.
The first group received 946ml of energy drink, while the second group was given a control drink containing 320mg of caffeine, 40 ml of lime juice and 140 ml of cherry syrup in carbonated water.
Researchers measured the electrical activity of the volunteers’ hearts by electrocardiogram and their blood pressures at the study’s start and at one, two, four, six and 24 hours after drink consumption.
They found that, when compared to the caffeine group, those in the energy drink group were showing signs of the heart ‘pausing’ for an extra 10 milliseconds between beats.
‘It’s the pause from the end of the electrical impulse generating the heart to beat to the next impulse,’ Dr Fletcher said.
‘If this time interval, which is measured in milliseconds, is either too short or too long, it can cause the heart to beat abnormally. The resulting arrhythmia can be life threatening.’
She said some medications increase this pause by 6 milliseconds and have warnings about the effect on product labels – whereas energy drinks seem to have a bigger impact.
Dr Fletcher added: ‘Those who consumed the energy drinks still had a mildly elevated blood pressure after six hours.
‘This suggests that ingredients other than caffeine may have some blood pressure altering effects, but this needs further evaluation.’
But she admitted: ‘This is a small study and further studies are needed to confirm these results.’
Gavin Partington, director general of the British Soft Drinks Association, said: ‘Caffeine in energy drinks is no different to caffeine in coffee so these findings are somewhat odd.
‘The European Food Safety Authority latest opinion confirms the safety of energy drinks and their ingredients and therefore does not provide any scientific justification to treat energy drinks any differently to the main contributors to daily caffeine intake including tea, coffee and chocolate.
‘It’s also worth remembering that coffees from popular high street chains contain the same or more caffeine than most energy drinks.’