New U.S. research has found that using e-cigarettes can be effective in helping smokers quit, but success can depend on how much smokers use them.

Carried out by researchers from Georgetown Lombardi Comprehensive Cancer Center, the team used data from the national Tobacco Use Supplement to the Current Population Survey (TUS-CPS) to look at the relationship between the frequency of e-cigarette use, the number of attempts to quit cigarettes, and cigarette abstinence.

The study, published online in Nicotine & Tobacco Research, included 24,500 current or recent former cigarette smokers taken from the TUS-CPS survey, the largest sample of smokers studied to date.

The team also looked at research published back in July in the BMJ, which, according to the new study's lead author David Levy, together helped provide some of the strongest evidence found so far on the link between use of e-cigarettes and quitting smoking.

The data showed that having made an attempt to quit smoking was more likely among smokers using e-cigarettes than non-users.

However, as found in other randomized trials and observational studies, the results also showed that the cigarette quit attempts and quit success were directly related to the number of days of e-cigarette use.

Among smokers who had made at least one quit attempt, quit success was lower among those who had used e-cigarettes at some point in the past, but higher among those who had used e-cigarettes for at least five days in the last month, with the chances of successfully quitting increasing by 10 percent with each additional day of e-cigarette use.

Commenting on the significance of the findings Levy concluded that, "These results support the use of e-cigarettes -- especially, consistent use -- as an effective smoking cessation aid. Since e-cigarettes are generally estimated to have a small proportion of the mortality risks of cigarettes, this represents an important life-saving intervention that doctors can recommend when other forms of treatment fail."

New U.K. research also out this week found that despite concerns, the majority of young people who experiment with e-cigarettes don't turn into regular users.

However, previous studies revealed mixed results about the safety of e-cigarettes, with more research needed to determine the safety of the relatively new product.