A large test of cigarettes with reduced nicotine finds that they help smokers cut down on the number of smokes they consume each day, at least in the short term, and that cigarettes with the lowest nicotine levels may even encourage smokers to quit.

The cigarettes tested were not the "low-nicotine" or "light" products that have been on the market for decades. Those brands used tobacco with regular nicotine levels and a vent system that tries to make it harder for a smoker to inhale the powerfully-addictive substance.

After their introduction, studies showed that smokers quickly learned how to manipulate them to inhale enough nicotine anyway.

"Smokers got around it by inhaling more deeply and more often. That's been the accepted truism," said Dr. Norman Edelman, senior scientific advisor for the American Lung Association, who was not involved in the research. "Now here comes this very well done study and it shows that if you simply reduce the nicotine in the tobacco, that doesn't seem to happen. Smokers don't seem to increase their consumption of cigarettes because they're getting less nicotine."

"These cigarettes don't have much nicotine in the tobacco itself, so no matter what the user does, it's just not there to extract," chief study author Eric Donny of the University of Pittsburgh told Reuters Health.

"This is a very different approach, and this one might make smokers less dependent on cigarettes and better able to quit," he said.

In their study, published in The New England Journal of Medicine, Donny and his colleagues found that an 85 percent to 97 percent reduction in nicotine produced a 23 percent reduction in the number of cigarettes smoked.

And participants who spent six weeks smoking the cigarettes with the lowest nicotine content were twice as likely to report trying to quit smoking within 30 days after the end of the study.

The experiment was done on 840 smokers who told the investigators when they signed up that they had no interest in quitting. They were paid up to $835 for their participation. The researchers used questionnaires to measure smoking dependence, nicotine withdrawal, depression and craving.

The study, the largest ever done on reduced-nicotine cigarettes, was designed to give the U.S. Food and Drug Administration a scientific basis for cutting back on the addictive chemical in tobacco products.

"We believe these data support exploration of a national nicotine-reduction policy, and we recommend that additional attention be paid to low-nicotine cigarettes as a potential clinical smoking-cessation resource," Drs. Michael Fiore and Timothy Baker of the University of Wisconsin School of Medicine and Public Health write in a Journal commentary.

Edelman, however, said he doubts the new findings will be enough to impose regulations.

"Whether you can leap from this to a new policy is kind of problematic," he said. "The study was only six weeks. In the smoking cessation business, we don't even look at a six week study. Six months or a year is the real test of whether an intervention is effective or not."

All the volunteers were smoking at least five cigarettes per day. They were told to smoke their regular brand or experimental cigarettes - all provided free of charge - with one of six different levels of nicotine. At the end of the six-week test study, they were asked to abstain for at least 18 hours so their craving and withdrawal symptoms could be measured.

Cigarettes typically have about 15.8 milligrams of nicotine per gram of tobacco. When nicotine levels were reduced to as low as 5.2 mg, the researchers saw no significant change in smoking behavior.

But when the nicotine levels dropped to 2.4 mg or lower, the number of cigarettes smoked showed a modest decline. Smokers went from 21.3 cigarettes per week with 15.8 mg of nicotine to 16.5 cigarettes per week with 2.4 mg of nicotine.

The same effect was seen when the nicotine level was dropped even lower, to 0.4 mg, a level believed to be too low to be addicting.

People on the low-nicotine cigarettes also reported less craving and less dependence.

Thirty days after the end of the study, about 35 percent of the volunteers who had been smoking the low-nicotine cigarettes had tried to quit versus 17 percent of those consuming regular-strength cigarettes.

"Whether cigarettes have lots of nicotine or a little bit of nicotine, they're still unsafe," Edelman said. "The best way of protecting your health is to quit."