Conventional wisdom says reduce nicotine in cigarettes and smokers will smoke more. A study showed exactly the opposite. So should the FDA cap nicotine content?

Give smokers cigarettes with dramatically lower nicotine content, and they will smoke less, not more.

Those are the surprising findings of a six-week study of more than 800 smokers, published today in the New England Journal of Medicine.

The study participants’ behavior defied the conventional wisdom that reducing nicotine will just lead addicts to smoke more.

That’s what happened with light cigarettes, which deliver less tar and nicotine per puff. Tobacco companies marketed them as a healthier alternative, but public health researchers found that smokers of light brands just inhaled more deeply to get the same dose of nicotine.

But the cigarettes in the study made it impossible for the smokers to get their usual dose of nicotine, so their smoking habit was not reinforced with a chemical reward. Some of the study cigarettes contained only about one-sixteenth of the nicotine found in a standard cigarette.

“People seem perfectly content to smoke these lower-nicotine cigarettes, not only perfectly content, but it appeared that because they got less satisfaction, they were more interested in quitting,” said Dr. Norman Edelman, a senior scientific advisor for the American Lung Association. Edelman was not involved with the study.

Eric Donny, Ph.D., a University of Pittsburgh psychologist who specializes in addiction, led the study. He explained why smokers likely responded differently to low-nicotine cigarettes than they do to light cigarettes.

“If you gave [smokers] half the nicotine, they might try to smoke twice the cigarettes. In other words, they still can change their behavior enough,” he said.

“If you reduce the nicotine by 90 percent, then it becomes difficult or impossible for them to maintain their smoking habits,” Donny continued. “What happens is that they don’t try to compensate. They end up smoking less.”

Some participants cheated, Donny acknowledged, perhaps picking up a pack at the corner store.

But participants had significantly less nicotine in their systems at the end of the study and the amount of carbon monoxide in their systems confirmed that they were not smoking more.

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The study came in response to a call for research put out by the Food and Drug Administration (FDA), which regulates tobacco products.

The FDA could, with the stroke of the pen, require cigarettes sold in the United States to slash their nicotine content. The nicotine can be extracted from tobacco, like the caffeine is from coffee, Donny said.

But to crack down on nicotine, the FDA would have to show that doing so would improve public health.

That’s the question Donny’s study sought to answer, with funding by the FDA Center for Tobacco Products and the National Institute on Drug Abuse. Most other countries around the world can also regulate the amount of nicotine in cigarettes.

But the FDA also has to consider whether bringing down the nicotine content in cigarettes would give the public the false impression that cigarettes are safe, Edelman said.

“There is a theoretical downside that the public thinks they’ve made cigarettes safer and that may lead them not to try to quit so hard or be less afraid to start,” he said.

Nicotine is the addictive ingredient in cigarettes, but it is not the most dangerous. Oxidants, fine particles and, especially, tar pose serious health threats.

“People smoke for the nicotine, but they die for the tar,” the NEJM editors wrote in a note accompanying the study.

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If less nicotine means less smoking, are nicotine patches, Snus, and e-cigarettes misguided approaches to helping smokers quit?

No, Donny said.

He pointed to a survey that participants took at both ends of the study that indicated they were less physically dependent on nicotine. That means it may be easier for them to quit.

People who were assigned the lowest nicotine-content cigarettes were twice as likely to quit in the month following the study as those who smoked the strongest study-provided cigarettes.

“I do think that breaking the connection between cigarettes and nicotine is an important direction,” Donny said. “However, I don’t think it means the alternative approach of providing clean nicotine is not useful.”

Edelman agreed. Addiction is more complicated than that.

“You have to understand that the people smoke not simply because of addiction to nicotine, smoking is also a very powerful habit,” he said. “Nicotine replacement addresses the addiction part of the problem. This really addresses the habit part of the problem. It says we’re going to cut down on the nicotine, but we’ll kind of let you keep your habit.”