- A UK policy model estimated that 841,302 smokers and ex-smokers do not smoke because flavoured vaping liquids are available.
- The same model estimated that 125,034 non-smoking young people experiment with vapes because of flavours, with 48,764 subsequently smoking under its assumptions.
- The model suggested that restricting the market to unflavoured, tobacco-flavoured or menthol-flavoured vapes could have a detrimental impact on adult smoking rates.
- A separate US randomised trial found that providing vapes helped smokers across demographic and smoking-history groups, with no significant differences by motivation to quit, dependence, age, sex, race, education or mental health diagnosis.
Restricting vape flavours could increase adult smoking by weakening quit attempts and raising relapse risk, according to a UK policy model.
The study, published in Health Research Policy and Systems, estimated that 841,302 smokers and ex-smokers in the UK do not smoke because flavoured vaping liquids are available.
By comparison, it estimated that 125,034 non-smoking young people experiment with vapes because of flavours, and that 48,764 subsequently smoke under the assumptions used in the model.
The authors said the algorithm indicated that if only unflavoured, tobacco-flavoured or menthol-flavoured vapes remained on the market, the negative impact on adult smoking rates would outweigh the number of young people protected from vaping and later smoking.
The findings come alongside a separate US randomised clinical trial analysis, published in Addictive Behaviors, which found that the smoking reduction and cessation effects of providing vapes were similar across a broad range of adult smokers.
Together, the studies add to the evidence base facing policymakers as governments try to reduce youth vaping without making it harder for adult smokers to quit cigarettes.
Flavours and smoking relapse
The UK study was designed as a policy decision aid to help officials weigh up the potential benefits and harms of vape flavour restrictions.
It was originally commissioned by Public Health England, now the Office for Health Improvement and Disparities, and uses existing data to estimate whether removing flavours other than tobacco or menthol would produce a net benefit or a net detriment.
The model drew on data from Action on Smoking and Health surveys, the Smoking Toolkit Study, the Office for National Statistics and UK population estimates. It was updated using evidence available on 13 November 2024.
Among young people aged 11 to 20, the model estimated there were just over 8.07 million people in the UK. Combining weighted youth survey data, the researchers estimated that 79 per cent of 11 to 20-year-olds had never smoked. Of that group, 14 per cent had tried vaping, and 14 per cent of those said they vaped because they liked the flavours.
Using those inputs, the model estimated that 125,034 non-smoking young people experiment with vapes because of flavoured liquid availability. It then estimated that 48,764 non-smoking young people subsequently smoke as a result of flavoured liquid availability, under the model’s assumptions.
On the adult side, the model used an estimate of six million current smokers and 17.3 million ex-smokers. It estimated that 13 per cent of adult smokers had quit in the past year using vapes.
Among current adult dual users and those who had quit within the previous year using a vape, 59 per cent said they would “smoke more tobacco” or “go back to smoking tobacco” if flavours became unavailable. Among ex-smokers who vape, 11 per cent said they would do the same.
The model estimated that 841,302 smokers and ex-smokers do not smoke because flavoured vaping liquids are available.
Youth protection versus adult quitting
The issue facing policymakers is that flavours can appeal to young people while also helping some adult smokers switch away from cigarettes.
The UK study didn’t argue that flavour policy should be decided by the model alone. The authors said the tool was intentionally simple and should be used alongside other evidence, including evidence from countries with similar regulatory environments.
The paper also set out several limitations. The model uses anticipated behaviour if flavours were removed, rather than observed behaviour after a UK ban. It does not account for every possible behavioural change, including the possibility that vaping may displace smoking among some young people.
It also assumes that vaping can act as a gateway to smoking. However, the authors noted that the relationship between vaping and later smoking is unlikely to be fully explained by a gateway effect and may partly reflect shared risk factors.
Even with those caveats, the model’s output was clear. On the evidence used, restricting flavoured vape liquids in the UK could have a detrimental overall effect when youth vaping, youth smoking uptake, adult smoking cessation and relapse are considered together.
Vapes helped smokers across groups
The second study looked at whether the effect of providing vapes differed between different types of adult smokers.
Researchers analysed data from a large naturalistic randomised clinical trial in the US, involving 638 adults who smoked. Participants were randomised on a 2:1 basis either to receive a four-week supply of tank-style vapes or to receive no product.
Those in the vape group received minimal guidance and were told they could use the products as much or as little as they liked. Outcomes were tracked to week 24.
The analysis looked at three main outcomes: whether participants made a 24-hour quit attempt, whether they reduced their cigarettes per day by at least 50 per cent, and whether they reported seven-day point prevalence abstinence. These were measured at week four and week 24.
Researchers tested more than 10 demographic and smoking-history variables, including age, sex, race, rurality, education, mental health diagnosis, nicotine dependence, previous quit attempts, prior vape use, household smoking or vaping, motivation to quit, and perceptions of the harms of smoking and vaping.
None of the group-by-moderator interactions were statistically significant for any outcome at either time point.
That means the relative effect of being given vapes did not appear to differ meaningfully across the groups tested.
The finding was particularly notable for motivation to quit. Smokers with higher motivation to quit had better raw cessation outcomes overall. But the relative effect of vapes on cutting cigarette consumption by at least half after four weeks was similar among smokers with low motivation to quit and those with high motivation to quit.
For low motivation smokers, the relative risk for reducing cigarettes per day by at least 50 per cent at week four was 3.71. For high motivation smokers, it was 3.56.
A similar pattern was seen for nicotine dependence. The relative risk of cutting cigarette consumption by at least half at week four was 3.69 among smokers with low dependence and 3.51 among those with high dependence.
Implications for policy
The US analysis doesn’t directly answer the UK flavour policy question. It was based on adult smokers in the US and examined vape provision, rather than flavour restrictions.
However, it found similar smoking reduction and cessation effects across a broad range of adult smokers, including those with lower motivation to quit.
The UK model examined a different question. It estimated that flavoured vape availability was linked to youth vaping and later smoking, but also to a larger number of adults not smoking because flavours were available.
Both studies add to the evidence base for policymakers weighing youth vaping concerns against the role of vapes in adult smoking cessation and relapse prevention.
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