Smokers who use e-cigarettes are likely to stop or reduce their smoking, claims an independent review of trial data.

Almost one in 10 smokers using e-cigarettes had been able to quit the habit up to a year later, and around one-third had cut down.

The review of two trials is published today in The Cochrane Library, the world’s leading producer of systematic reviews.

Controversy continues over whether e-cigarettes have net benefits, amid fears that using them in public places will ‘re-normalise’ smoking, especially among young people, and reverse declining smoking rates.

The independent review of two trials has revealed almost one in 10 smokers using e-cigarettes had been able to quit the habit up to a year later, and around a third had cut down

Professor Peter Hajek of the UK Centre for Tobacco and Alcohol Studies at QMUL, co-author of the review, said smokers wanting to quit who had failed using conventional aids such as patches should try buying e cigarettes.

The trial data showed no serious adverse effects from short to medium term use, he said.

‘Although our confidence in the effects of electronic cigarettes as smoking cessation interventions is limited because of the small number of trials, the results are encouraging’ he said.

Around 2.1 million Britons use battery-powered e-cigarettes - devices allowing users to inhale nicotine while avoiding the harm caused by tobacco smoke.

It is estimated that two thirds are current smokers, many of who are trying to quit, and most of the remainder are ex-smokers.

The UK’s drug watchdog has decided they must be regulated as medicines to make the products ‘safer and more effective’ but this won’t happen until 2016.

In Wales, health legislators are consulting on plans to make the principality the first part of the UK to ban e-cigarettes in enclosed public places.

Some countries have banned them altogether including Norway, Singapore, Brazil, along with Western Australia.

The World Health Organisation claimed in August that the devices pose a risk to bystanders through emissions of ‘toxicant’ substances and warned of limited evidence they help people quit smoking.

The Cochrane review looked at two trials involving 662 current smokers, and 11 observational studies.

Some experts fear e-cigs act as a gateway to smoking in younger people, who might not have started smoking otherwise (file picture)

About nine per cent of smokers who used e-cigarettes were able to stop smoking at up to one year, compared with four per cent of those in the trial using nictotine-free e-cigarettes.

The researchers found 36 per cent of e-cigarette users halved the number of conventional cigarettes they used, compared with 28 per cent getting the nicotine-free alternative.

Professor Hajek said critics who claimed e-cigarettes might contain some toxins should realise they are not being compared with ‘fresh air’ but the known harms of conventional cigarettes.

The furore over e-cigarettes and unexpected opposition from some quarters, including public health doctors, was possibly due to it being a ‘disruptive technology’, he said.

It threatens vested interests, from tobacco manufacturers to those with ‘established public health positions’ he added.

Professor Robert West, editor-in-chief of Addiction and Director of Tobacco Research at University College London, said: ‘This study tells us that even the older style electronic cigarettes improve smokers’ chances of stopping by about 50 per cent.

‘It’s early days but so far it seems that these devices are already helping tens of thousands of smokers to stop each year.’

Dr John Middleton, vice president for Policy at the Faculty of Public Health said: ‘Our position remains that while e-cigarettes may help smokers who want to quit, we don’t yet have enough evidence yet of the impact they are having on other people, particularly children and smokers who also use e-cigarettes.

‘There’s good evidence that most people start smoking in their teens and that the most effective way to stop smoking is through NHS quit smoking services.

‘It has taken decades of sustained effort to create a society in the UK where smoking is now not seen as the norm.