Nearly all of those who use e-cigarettes are current smokers or former smokers using them as a cessation device.
Despite this finding, the reviewers also state that around 44.8% of people are unaware that using e-cigarettes - also referred to as "vaping" - is less harmful than traditional smoking.
The review was commissioned by Public Health England, an agency of the UK's Department of Health, and was led by Prof. Ann McNeill of King's College London and Prof. Peter Hajek of Queen Mary University of London.
According to their findings, e-cigarettes appear to be contributing toward falling rates of smoking among both adults and young people.
"There is no evidence that e-cigarettes are undermining England's falling smoking rates," states Prof. McNeill. "Instead the evidence consistently finds that e-cigarettes are another tool for stopping smoking, and in my view, smokers should try vaping and vapers should stop smoking entirely."
The researchers found that nearly all of the 2.6 million adults in Great Britain who report using e-cigarettes are either current smokers or ex-smokers, using the devices to help them stop smoking or prevent them from picking up the habit again.
Less than 1% of adults and young people who have never smoked are regular e-cigarette users. The researchers state that the evidence suggests e-cigarettes attract few people who have never smoked into regular use.
The review draws attention to recent worldwide media headlines asserting that e-cigarette use is dangerous. After analyzing these reports, the researchers concluded that they were based on misinterpreted research findings.
"While vaping may not be 100% safe, most of the chemicals causing smoking-related disease are absent and the chemicals that are present pose limited danger," they write.
'Highest successful quit rates seen among e-cigarette users'
Prof. Hajek believes that smokers should give e-cigarettes a try:
"My reading of the evidence is that smokers who switch to vaping remove almost all the risks smoking poses to their health. Smokers differ in their needs and I would advise them not to give up on e-cigarettes if they do not like the first one they try. It may take some experimentation with different products and e-liquids to find the right one."
Dr. Penny Woods, chief executive of the British Lung Foundation, says that Public Health England are to be applauded for taking the lead in outlining the evidence currently available on e-cigarettes, and that e-cigarettes have a good record at helping smokers to quit.
"While smoking cessation services continue to be the most successful way to help people stop smoking, the highest successful quit rates are being seen among smokers who are also using e-cigarettes," she states. "Providing health care professionals with accurate advice and information on their use is necessary if we are to unlock the full potential of e-cigarettes in helping people to kick their habit."
The review also finds that smoking is most common among disadvantaged groups who tend to be more dependent on the habit. E-cigarettes could represent a wide-reaching low-cost intervention to reduce smoking rates in such advantaged groups, the researchers suggest, and consideration should be given to using the devices as part of a proactive strategy to encourage smoking cessation.
Due to the amount of people that the study found to be unaware of how safe e-cigarettes are, the researchers state that clear and accurate information on the relative harm of nicotine, e-cigarettes and tobacco cigarettes is needed urgently.
Another finding of the review is that there is no evidence at present that e-cigarettes act as a gateway into smoking for children or nonsmokers. This finding is in contrast with a recent study of high school students published in JAMA.
In that study, researchers found that students who reported having used e-cigarettes at the baseline were more likely to go on to use combustible tobacco products than those who had never used e-cigarettes.