Researchers at University College London (UCL) analyzed the latest data on smoking and quitting in England - including details on smokers who worked with the health-worker devised Stop Smoking Services to set a quit date.
While they found no direct evidence that e-cigarettes prompted more people to make the decision to try and quit, the team did find that as more people used e-cigarettes, more people also successfully stopped smoking.In a separate scientific analysis also published on Tuesday, researchers at the Cochrane Review found that the overall weight of evidence on e-cigarettes suggests they can help people stop smoking and have no serious side-effects.
E-cigarettes, which heat nicotine-laced liquid into vapor, have rapidly grown into a global market for "vaping" products that was estimated at around $7 billion in 2015.
Unlike nicotine chewing gum and patches, they mimic the experience of cigarette smoking because they are hand-held and generate a smoke-like vapor.
Tobacco smoking kills half of all those who indulge, plus at least another 600,000 non-smokers a year via second-hand smoke. This makes it the world's biggest preventable killer, with a predicted death toll of a billion by the end of the century, according to the World Health Organization (WHO).
Many public health specialists think e-cigarettes, or vapes, which do not contain tobacco, are a lower-risk alternative to smoking, but some question their long-term safety.
Experts estimate that around 2.8 million people in the UK use e-cigarettes and they have become the nation's most popular smoking cessation aid.
"England is sometimes singled out as being too positive in its attitude to e-cigarettes," said Robert West, a professor at UCL's Health Behaviour Research Centre who co-led the study and published it in the BMJ British Medical Journal.
"These data suggest that our relatively liberal regulation of e-cigarettes is probably justified."
In the second analysis, a review published by the Cochrane Library, researchers also found e-cigarettes may help people quit but said there is not yet enough evidence from the best type of studies - randomized controlled trials - to be sure.
Of the studies that looked at side effects and were reviewed by the Cochrane team, none found any serious concerns of using e-cigarettes for up to two years. Among non-serious side-effects, throat and mouth irritation were most common.