11/09/2017 15:21 BST

Could E-Cigarettes Containing Nicotine Increase Your Risk Of Heart Attack?

Another day, another study.

E-cigarettes have long proven divisive. While Public Health England (PHE) suggests they are roughly 95% less harmful than tobacco, a number of smaller studies have shared conflicting evidence. 

The latest to challenge e-cigarette safety comes from the Karolinska Institute’s Dr Magnus Lundbäck and his colleagues.

When volunteers were exposed to e-cigarettes containing nicotine, Dr Lundbäck and his team found there was a “significant increase” in heart rate and blood pressure, as well as arterial stiffness, which has previously been linked to heart attack and stroke.

But Deborah Arnott, chief executive of public health charity Action on Smoking and Health (ASH), said we shouldn’t just single out e-cigarettes in this instance, because “drinking coffee can also cause arterial stiffness, as can other substances”.

She told HuffPost UK: “This should not make those people considering switching from smoking to vaping, or those who have already switched, change their mind.”

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Dr Lundbäck and his team recognised e-cigarette usage had increased dramatically over the last few years, which is why they wanted to analyse the health effects further. 

“E-cigarettes are regarded by the general public as almost harmless,” Dr Lundbäck said. “The e-cigarette industry markets their product as a way to reduce harm and to help people to stop smoking tobacco cigarettes. However, the safety of e-cigarettes is debated, and a growing body of evidence is suggesting several adverse health effects.”

The research team recruited 15 young, healthy volunteers to take part in the study in 2016.

The volunteers had previously smoked a maximum of 10 cigarettes a month and they had not used e-cigarettes before the study. The average age was 26, with 59% being female and 41% being male.

Volunteers were asked to use e-cigarettes with nicotine for 30 minutes on one of the study days and e-cigarettes without nicotine on the other day.

Researchers measured blood pressure, heart rate and arterial stiffness immediately after smoking the e-cigarettes and then two and four hours later.

In the first 30 minutes after smoking e-cigarettes containing nicotine, there was a significant increase in blood pressure, heart rate and arterial stiffness, they found.

However no such effect was seen on heart rate and arterial stiffness in the volunteers who had smoked e-cigarettes without nicotine.

“The immediate increase in arterial stiffness that we saw is most likely attributed to nicotine,” said Dr Lundbäck. “The increase was temporary. However, the same temporary effects on arterial stiffness have also been demonstrated following use of conventional cigarettes.

“Chronic exposure to both active and passive cigarette smoking causes a permanent increase in arterial stiffness. Therefore, we speculate that chronic exposure to e-cigarettes with nicotine may cause permanent effects on arterial stiffness in the long term.”

What we know about e-cigarettes so far.

Information previously released by Public Health England (PHE) suggested that e-cigarettes were roughly 95% less harmful than tobacco, making them a great alternative for people looking to quit smoking. A study published earlier this year by a team of scientists at University College London (UCL) reiterated this. 

However there are a number of smaller studies suggesting e-cigarettes could still pose a risk to health.

One 2015 study warned that vapour from the devices could damage or even destroy human cells, which led Dr Wang-Rodriguez, chief of pathology at the San Diego branch of the US Department of Veteran Affairs and co-author of the study, to make the following statement: “Based on the evidence to date I believe they [e-cigarettes] are no better than smoking regular cigarettes.”

Another study from earlier that year noted the presence of formaldehyde - a substance known to cause cancer in human tissue - in the vaporised liquid of e-cigarettes. The report published in the New England Journal of Medicine suggested the exposure to formaldehyde from e-cigarettes could be five to 15 times higher than from smoking cigarettes.

With the latest study, Dr Lundbäck said the results emphasised the need for a “critical and cautious attitude towards e-cigarettes”, especially for healthcare professionals.

He concluded: “E-cigarette users should be aware of the potential dangers of this product, so that they can decide whether to continue or quit based on scientific facts.”