If quitting smoking is one of your New Year's resolutions, you might want to consider cutting back on your drinking too, a study suggests.

Researchers from Oregon State University in the US found that reducing alcohol use can help people quit their smoking habit.

Heavy drinkers' nicotine metabolite ratio --  that indicates how quickly a person's body metabolises nicotine -- reduced as they cut back on their drinking, according to the study published in the journal Nicotine & Tobacco Research.

Past research has suggested that people with higher nicotine metabolism ratios are likely to smoke more and that people with higher rates have a harder time quitting.

Slowing a person's nicotine metabolism rate through reduced drinking could provide an edge when trying to stop smoking, which is known to be a difficult task, said Sarah Dermody, an assistant professor at Oregon State University.

"It takes a lot of determination to quit smoking, often several attempts," Dermody said.

"This research suggests that drinking is changing the nicotine metabolism as indexed by the nicotine metabolite ratio, and that daily smoking and heavy drinking may best be treated together," she said.

Use of both alcohol and cigarettes is widespread, with nearly one in 5 adults using both. Cigarette use is especially prevalent in heavy drinkers, researchers said.

Drinking is a well-established risk factor for smoking, and smoking is well-established risk factor for drinking, they said.

Dermody and colleagues at the Centre for Addiction and Mental Health in Canada, wanted to better understand the links between the two.

They studied the nicotine metabolite ratio, an index of nicotine metabolism, in a group of 22 daily smokers who were seeking treatment for alcohol use disorder -- the medical term for severe problem drinking -- over several weeks.

They found that as the men in the study group reduced their drinking -- from an average of 29 drinks per week to 7 -- their nicotine metabolite rate also dropped.

The findings for men replicated those of an earlier study that found similar effects and provide further evidence of the value of the nicotine metabolite ratio biomarker to inform treatment for smokers trying to quit, Dermody said.

"The nicotine metabolite ratio was thought to be a stable index, but it may not be as stable as we thought," Dermody said.

The women in the study did not see reductions in their nicotine metabolite ratio, but the researchers also did not find that the women in the study reduced their drinking significantly during the study period.