MONDAY, March 24, 2014 (HealthDay News) -- Contrary to some advertising claims, electronic cigarettes don't help people quit or cut down on smoking, a new study says.

Users of e-cigarettes inhale vaporized nicotine but not tobacco smoke. The unregulated devices have been marketed as smoking-cessation tools, but studies to date have been inconclusive on that score, the study noted.

"When used by a broad sample of smokers under 'real world' conditions, e-cigarette use did not significantly increase the chances of successfully quitting cigarette smoking," said lead researcher Dr. Pamela Ling, an associate professor at the Center for Tobacco Control Research and Education at University of California, San Francisco.

These findings -- based on nearly 1,000 smokers -- are consistent with other studies and contradict the claims frequently found in e-cigarette advertising, she said.

"Advertising suggesting that e-cigarettes are effective for smoking cessation should be prohibited until such claims are supported by scientific evidence," Ling said.

For the study, Ling's team analyzed data reported by 949 smokers, 88 of whom used e-cigarettes at the start of the study.

One year later, 14 percent of the smokers had quit overall, with similar rates in both groups.

"We found that there was no difference in the rate of quitting between smokers who used an e-cigarette and those who did not," Ling said.

There was no relationship between e-cigarette use and quitting, even after taking into account the number of cigarettes smoked per day, how early in the day a smoker had a first cigarette and intention to quit smoking, Ling added.

However, the researchers noted that the small number of e-cigarette users may have limited the ability to find an association between e-cigarette use and quitting.

The report, published online March 24 in JAMA Internal Medicine, also found that women, younger adults and people with less education were most likely to use e-cigarettes.

One expert said the study is flawed and shouldn't be taken seriously.

"It's an example of bogus or junk science," said Dr. Michael Siegel, a professor of community health sciences at Boston University School of Public Health.