Senior Robert West of University of College London's Department of Epidemiology & Public Health and colleagues surveyed 5,863 smokers from 2009 to 2014 who had attempted to quit smoking without the aid of prescription medication or professional support.
The study, published in Addiction, found 20 percent of the adults trying to quit with the aid of e-cigarettes reported they stopped smoking conventional cigarettes at the time of the survey.
"E-cigarettes could substantially improve public health because of their widespread appeal and the huge health gains associated with stopping smoking," West said in a statement.
"However, we should also recognize that the strongest evidence remains for use of the National Health Service stop-smoking services. These almost triple a smoker's odds of successfully quitting compared with going it alone or relying on over-the-counter products."
"It is not clear whether long-term use of e-cigarettes carries health risks but from what is known about the contents of the vapor these will be much less than from smoking," West said.
"Some public health experts have expressed concern that widespread use of e-cigarettes could 're-normalize' smoking. However, we are tracking this very closely and see no evidence. Smoking rates in England are declining, quitting rates are increasing and regular e-cigarette use among never smokers is negligible."