A new study being published in the American Journal of Health Behavior suggests that electronic cigarettes might encourage hard-core tobacco puffers to significantly cut back on traditional cigarettes, even when they say they don't want to.
The pilot study found that of 28 adult smokers—none of whom were interested in quitting—25, or nearly 90 percent, reduced their use of tobacco cigarettes during a week in which they smoked e-cigarettes from leading maker NJOY.
Nearly one-third of those smokers cut their tobacco cigarette use in half, and four of the participants told researchers that they were smoking no traditional cigarettes at all by the end of the weeklong trial of NJOY Kings.
Overall, the mean reduction in participants' cigarettes smoked per day was 39 percent, according to the study.
The research report also found that the e-cig users' nicotine absorption was comparable to that with nicotine-replacement products approved by the Food and Drug Administration. The report noted that "these results suggest that this [NJOY] product delivered enough nicotine to suppress craving."
Further research needed
Mitchell Nides, who co-led the research with Scott Leischow of the Mayo Clinic, called the results "a very good signal to go forward" with more research on whether e-cigarettes can lead to long-term cessation of tobacco cigarette use.
He noted that the study did not follow up with to see if participants' tobacco use remained lower after the trial.
(Read more: E-Cig boom could be around the corner)
"They have tremendous potential as [a] smoking-cessation aid," said Nides, who has conducted studies on tobacco cessation for more than 25 years. He added that he was "surprised" by the four participants that stopped using cigarettes altogether.
"I think there's real potential for efficacy, with potentially few side effects," he said. "Obviously, more research is needed."
The study, which was funded by NJOY, comes at a key moment for e-cigarettes, which deliver nicotine by vaporizing a nicotine-infused liquid for inhalation without the smell of tobacco cigarettes.
E-cigarette sales have exploded, and are expected to reach as much as $1 billion this year (though still a tiny fraction of the $80 billion in annual sales for tobacco cigarettes).
The fast-growing market, combined with the desire of many smokers to quit, has drawn the keen attention of Big Tobacco. All three of the major companies will enter the e-cig business this year. At the same time, the FDA is poised to issue proposed regulations on the category, which could affect sales.
(Read more: E-cigs jockey for market position ahead of FDA regs)
Dr. Richard Carmona, who was a fierce critic of tobacco as surgeon general under President George W. Bush, joined NJOY's board of directors this spring and is chairman of its scientific advisory committee.
Carmona told CNBC.com that "we agree that no health claims should be made" for e-cigarettes "without the appropriate science" to support them. But, he added, "if we stopped tobacco use today, 80 percent of the lung cancers would go away—not today, but in the future.
"There's no tobacco" in e-cigarettes, he said. "We just have a different delivery system [for nicotine] that reinforces the habit of holding a cigarette, but without those toxic, carcinogenic properties."
Echoing Nides, Carmona said the next step should be finding out if e-cigarettes can help traditional users kick their tobacco habit in the long term. If they do, Carmona said, e-cigs could be a major factor for "harm reduction" among tobacco users.
(Read more: Reynolds sees its e-cig as "game-changer")
But the study itself concludes by saying "toxicological research is also needed to assess whether [e-cigarettes] deliver significant amounts of any potentially harmful substances besides nicotine, which is a relatively benign substance despite its primary role in dependence."
Dr. Alexander Prokhorov, a behavioral scientist who specializes in tobacco at the University of Texas MD Anderson Cancer Center, said nicotine dependence should not be discounted and that e-cigs could be a "gateway" to tobacco use by young people.
And he emphasized that the jury remains out on the question of the health risks of e-cigs.
"Unfortunately, there's no proof that e-cigarettes are risk-free," Prokhorov said.
—By CNBC's Dan Mangan. Follow him on Twitter @_DanMangan.