Electronic cigarettes could be as harmful to the heart as smoking regular cigarettes, scientists have warned.
Their study found that an average vaping session caused similar damage to the main artery in the heart - the aorta - as smoking cigarettes.
The study seems to contradict advice given by Public Health England (PHE) last year, which said vaping is 95% less harmful than tobacco.
At the time, PHE called for GPs to be able to prescribe e-cigarettes on the NHS to help people quit smoking.
To measure the damage cause by e-cigarettes, scientists monitored 24 adults with an average age of 30, examining the immediate effects of vaping compared to smoking.
They found that the effects from a 30-minute session of vaping - seen as a typical habit as e-cigarettes deliver nicotine at a slower rate than cigarettes - were similar to those from smoking a cigarette for five minutes.
The researchers, who presented their findings at the European Society for Cardiology congress, said they would not recommend using e-cigarettes.
According to the Press Association, Professor Charalambos Vlachopoulos, from the University of Athens Medical School, told the conference: “We measured aortic stiffness. If the aorta is stiff you multiply your risk of dying, either from heart diseases or from other causes.
“The aorta is like a balloon next to the heart. The more stiff the balloon is, the more difficult for the heart to pump. It’s the most powerful biomarker we have for estimating cardiovascular disease.”
Prof Vlachopoulos said that while the long-term risks of vaping remained unknown, he would not recommend their use.
He said: “There could be long-term heart dangers. They are far more dangerous than people realise. I wouldn’t recommend them now as a method to give up smoking. I think the UK has rushed into adopting this method.”
Commenting on the findings, Rosanna O’Connor, from PHE, told the Telegraph: “Vaping carries a fraction of the risk of smoking yet many smokers are still not aware, which could be keeping people smoking rather than switching to a much less harmful alternative.”