expert reaction to study looking at e-cigarette vapour and vascular effects in mice and smokers

Research, published in the European Heart Journal, reports on the relationship between e-cigarette use and damage to the brain, blood vessels, and lungs.  Experts from Science Media Centre react to the study.

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Prof Peter Hajek, Director of the Tobacco Dependence Research Unit, Queen Mary University of London, said:

“The authors detected two effects.  In human smokers, nicotine from e-cigarettes produced a typical acute stimulant effect, also seen after drinking coffee, that on its own signals no danger.  In mice and in tissue samples, acrolein, a chemical that can be generated when e-liquid is fried, had more damaging effects.  This however is not relevant for human vapers.  Frying e-liquid produces this chemical, but this also produces aversive taste that vapers avoid.  Human vapers have acrolein levels that are similar to non-smokers and much lower than in smokers.”

Prof Ajay Shah, Head of School of Cardiovascular Medicine & Sciences, and BHF Professor of Cardiology, King’s College London, said:

“This study convincingly shows that the use of e-cigarettes in people who are cigarette smokers causes a short-term additional impairment of the function of the inner lining of blood vessels – the endothelium.  It is recognised that persistent abnormal function of the endothelium predisposes in the long-term (several years) to furring up of the arteries which can lead to heart attacks or stroke.  The effect here of an e-cigarette vaping episode on the endothelium is similar to the short-term effects of cigarette smoking, high cholesterol or diabetes, but whether it would have similar long-term detrimental effects on health cannot be determined from this study.  It is important to note that the researchers did not study the effects of e-cigarettes on healthy non-smokers but only in people who regularly smoke cigarettes and whose endothelium may already be slightly abnormal – so we cannot fully extrapolate these results to non-smokers.  They also only studied the effects of one episode of vaping.

“The second part of the study was to expose mice to e-cigarette vapour for up to five days and assess the impact on vessels, the lungs and the brain.  The researchers found evidence of some damage to all these organs but these results are less straightforward to extrapolate to humans, and the researchers did not include all the appropriate control groups to improve confidence in this result.  The conclusions from the animal studies regarding possible effects on the lungs and brain therefore require further research in people to assess if the same happens in humans.  However, it is quite clear that e-cigarettes appear to cause potentially harmful effects on the endothelium in people who are regular cigarette vapers, indicating that they are not harmless.”

Click here to read all expert reaction –