Positive messages may be more effective at persuading smokers to quit than messages that emphasized the negative outcomes, according to a recent study.

A mix of messages might work to best help to convince some of the 45 million smokers in the United States to give up the habit.

However, the effectiveness of the words "Warning: Quitting smoking reduces the risk of cancer" beneath the image of an open mouth with a cancerous lesion and rotten teeth, or the same image with the words, "Warning: Quitting smoking reduces the risk of cancer," depends on how confident a smoker is in their ability to quit.

For the study, researchers from Georgetown University Medical Center collected and analyzed data from 740 participants and three D.C. area institutions.

They found that "gain-framed" messages -- those that stressed the benefits in quitting, such as "quitting smoking reduces the risk of death due to tobacco" -- were more effective for smokers who believed quitting would be hard.

On the other hand "loss-framed" messages -- the ones that emphasized the negative outcomes from smoking, such as "smoking can kill you" -- were more effective for smokers who thought they could quit when they wanted.

Most of the warnings used now on tobacco packages in the United States and worldwide, are loss-framed messages, which may not be sufficiently convincing to many smokers.

"This study shows us that leveraging both gain- and loss-framed messaging may prompt more smokers to quit," Darren Mays, the study's lead investigator, said in a statement.

"Leveraging policies such as graphic warnings for cigarette packs to help smokers quit is critical to improve public health outcomes. Our study shows that that framing messages to address smokers' pre-existing attitudes and beliefs may help achieve this goal," Mays said.

The findings were published in the journal Nicotine & Tobacco Research.