People planning to quit smoking in the New Year are more likely to succeed if they also stop drinking, according to new research.
Booze increases the rate at which the body breaks down nicotine – fuelling craving for another cigarette, suggests the study.
Cutting alcohol consumption slows down the process – making it easier to kick the habit, explained scientists.
It sheds fresh light on why most smokers have more cigarettes when they hit the bottle – and lots only smoke when they drink.
Study lead author Professor Sarah Dermody said: “If quitting smoking is one of your New Year’s resolutions, you might want to consider cutting back on your drinking, too.”
As regular drinkers know, people are more likely to reach for their packet of fags as they sup a glass of wine, beer or whisky.
And that makes them more thirsty too – a vicious cycle that has baffled experts for years.
Now a study of heavy drinkers has shown their nicotine metabolite ratio (NMR) fell as their alcohol intake decreased.
Tit is a biological marker in urine and saliva that indicates how quickly a person’s body metabolises the addictive ingredient in cigarettes.
Prof Dermody, a psychologist at Oregon State University in the US, said: “It takes a lot of determination to quit smoking, often several attempts.
“This research suggests 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.”
Earlier this year a study by University College London revealed tobacco and alcohol are the biggest threats to human health of all addictive substances.
They cause 110 and 33 deaths per 100,000 people, respectively – compared to just 6.9 from cocaine.
Prof Dermody said people trying to stop smoking may find reducing their alcohol use will help.
Previous research has suggested those with higher NMRs are likely to smoke more – and have a harder time quitting.
Slowing a person’s nicotine metabolism through less drinking could provide an edge when trying to give up – a notoriously difficult task, said Prof Dermody.
The study, published in the journal Nicotine And Tobacco Research, was based on 22 male and female daily smokers who were being treated for problem drinking.
Prof Dermody studies risky behaviours like alcohol and nicotine use with the goal of developing more effective treatments through better understanding of them. Almost one in five adults both drink and smoke, she said.
Her researchers analysed the NMR in 22 male and female daily smokers seeking treatment for alcohol use disorder – the medical term for severe problem drinking – over three weeks.
Prof Dermody said: “What is really interesting is the nicotine metabolite ratio is clinically useful. People with a higher ratio have a harder time quitting smoking cold turkey.
“They are also less likely to successfully quit using nicotine replacement therapy products.”
As the male participants reduced their drinking – from an average of 29 drinks a week to seven – samples of saliva and urine showed their NMR also dropped.
It replicated the results of an earlier study that found similar effects. It provides
further evidence of the value of the NMR biomarker to inform treatment for smokers trying to quit, Prof Dermody said.
“The nicotine metabolite ratio was thought to be a stable index, but it may not be as stable as we thought,” she said.
“From a clinical standpoint, that is a positive thing, because if someone wants to stop smoking, we may want to encourage them to reduce their drinking to encourage their smoking cessation plan.”
The women did not see falls in their NMR, but this may be because they only reduced their alcohol consumption by about two drinks a week, an proportionately insignificant amount.
Prof Dermody said: “The rate of drinking for women in the study started low and stayed low.
“I anticipate in a larger generalised study we would not see the difference between men and women like that.”
Cigarette use is especially prevalent in heavy drinkers. Prof Dermody said drinking is a well established risk factor for smoking – and vice-versa.
She said: “There were significant reductions in both salivary and urinary NMR over time for men, respectively, but not for women. Drinks per week were significantly reduced for men, but not for women.
“The reduction in alcohol use and NMR in men provides indirect support for alcohol increasing NMR.
“In contrast, the low baseline drinking and lack of alcohol reduction likely underlies the lack of change in NMR in females.
“The findings indirectly support that heavy drinking increases NMR, which is reversed with reduced drinking.
“Additional research is needed to establish if these changes in NMR correlate with smoking and cessation outcomes.”
She is now preparing a new study of the links by recruiting heavy drinkers who also smoke to participate in an intervention to reduce their alcohol intake.
The study will also examine the effects on smoking to try and replicate the findings in a larger group.
Prof Dermody added: “This research is demonstrating the value in addressing both smoking and drinking together. The question now is how best to do that.”
The UCL study reported in May suggested nearly one in five adults worldwide drink heavily at least once a month, while 15 per cent smoke tobacco every day.