Table 2

Sample characteristics, objectives and main findings on flavours' impact of included articles

Study ID (country)Sample size and study population (years old)Study aimMain findings on flavours' impact
 Amato et al,22 2016 (USA)N=9301
Adult (18+)
Users, non-users
Investigate patterns of e-cigarettes' use in order to establish a standard definition of e-cigarette current use prevalence for the purpose of population surveillance
  • Current e-cigarette users cited flavours as a reason for use more often than past users

 Berg,23 2016 (USA)N=1567
Young adult (18-34), e-cigarette users, non-users; cigarette users, non-users
Compare (1) e-cigarette never, current and former users; (2) never, current and former traditional cigarette smokers in relation to e-cigarette use characteristics, flavours preferred and reasons for use; and (3) reasons for discontinued use among former e-cigarette users across never, current and former smokers
  • Flavours were frequently indicated as reason for use across smoking and non-smoking e-cigarette users

 Czoli et al,24 2016 (Canada)N=915
Youth and young adult users and non-users (16–24 years); adult users (25+)
Determine the effect of distinct attributes of e-cigarettes (flavours, nicotine content, health warnings, price) and attribute levels on consumer choice
  • Flavours in e-cigarettes significantly predicted lower perceptions of product harm and ability to help someone quit smoking

 Etter,25 2010 (France, Belgium, Canada, Switzerland)N=81
Adult (19–65; median age=37)
Assess usage patterns of e-cigarettes, reasons for use and users’ opinions of these products
  • Adult e-cigarette users reported flavours as being the most positive feature of the product

 Farsalinos et al,26 2013 (survey online 10 languages)N=4618
Adults (32–49; mean age=40)
Examine the patterns and perceptions of flavouring use in e-cigarettes among dedicated users
  • E-cigarette users who were former smokers were more likely to prefer fruit and sweet flavours compared with current smokers

  • E-cigarette users reported that the variability of e-cigarette flavours was an important factor in reducing or quitting cigarette smoking and a greater number of flavours used was associated with smoking abstinence

 Farsalinos et al,27 2014 (survey online 10 languages)N=19 441
Adults (31–47; mean age=39)
Assess the characteristics and experiences of a large, worldwide sample of e-cigarette users and examine the differences between those who partially and completely substituted smoking with e-cigarette use
  • The variability of flavours was cited as one of the reasons for initiating e-cigarette use, though it was not a primary reason

 Ford et al,28 2016 (UK)N=1205
Youth (11–16), Users, non-users
Examine adolescents’ awareness of e-cigarette marketing and investigate the impact of e-cigarette flavour descriptors on perceptions of product harm and user image
  • Fruit and sweet flavours were perceived as more likely to be tried by young never smokers than adult smokers trying to quit

  • The perceived harmfulness of e-cigarettes was moderated by-product flavours

 Kong et al,29 2015 (USA)N=1157
Youth, young adult
Assess reasons for e-cigarette experimentation and discontinuation and examine whether these reasons differed by school level (middle school, high school, college) and cigarette smoking status
  • Availability of flavours was a primary reason for experimentation with e-cigarettes, and appealing flavours were particularly important to high school students

 Krishnan-Sarin et al,30 2015 (USA)N=4780
Youth (middle school mean age=12.18, high school mean age=15.63)
Users, non-users
Examine e-cigarette awareness, use patterns, susceptibility to future use, preferences, product components used and sources of marketing and access among youth
  • Use and preference for sweet e-cigarette flavours was high among adolescents regardless of cigarette smoking status

 Nonnemaker et al,31 2016 (USA)N=765
Adults (18+), current or former smokers
Examines how e-cigarette attributes influence willingness to pay for e-cigarettes
  • For cigarette-only users, losing flavours significantly reduced the price participants were willing to pay for e-cigarettes

 Pepper et al,32 2013 (USA)N=228
Youth (11–19), males
Users, non-users
Sought to understand awareness of and willingness to try e-cigarettes among adolescent males
  • Flavoured e-cigarettes did not increase male adolescents’ willingness to try e-cigarettes compared with plain varieties

 Pepper et al,33 2014 (USA)N=3878
Adult (18+)
Explore reasons for starting and then stopping e-cigarettes use and examine differences in discontinuation by reason for trying among population-based sample of US adults
  • Few adult e-cigarette users reported starting e-cigarette use because of the available flavours

 Shiffman et al,34 2015 (USA)N=216 (teens)
N=432 (adult)
Youth non-users (13–17)
Adult users (19-80)
Compare e-cigarettes interest between non-smoking teens and adult smoker, across flavours and assess differences in flavour preferences among adult smokers based on e-cigarettes use history
  • The interest of non-smoking teens in trying flavoured e-cigarettes was very low, and interest was not influenced by flavour descriptors. Though adult smokers’ interest was also modest, their interest was significantly higher than that of non-smoking teens for each flavour

 Shiplo et al,35 2015 (Canada)N=1095
Younger non-smokers and smokers (16–24), older smokers (25+)
Examines e-cigarette ever and current use, types of products used and reasons for use
  • Use of flavoured e-cigarettes varies by smoking status, with smokers being more likely to try flavours than non-smokers

  • A common reason for e-cigarette use is for the taste

 Tackett et al,36 2015 (USA)N=215
Adult (mean age=36.2)
Estimate e-cigarettes preference, e-cigarettes use behaviours, perceived harm and health beliefs of various smoking cessation medications, nicotine replacement therapies and nicotine/tobacco products and smoking history and current biochemically verified smoking status
  • Most e-cigarette users reported a preference for vaping non-traditional flavours.

  • Those who reported vaping non-tobacco and non-menthol flavours were more likely to have quit smoking

 Vasiljevic et al,37 2016 (UK)N=471
Youth (11–16)
Assess the impact on appeal of tobacco smoking after exposure to advertisements for e-cigarettes with and without candy-like flavours
  • Flavoured, compared with non-flavoured, e-cigarette advertisements elicited greater appeal, interest in buying and trying e-cigarettes

 Yingst et al,20 2015 (USA and other countries)N=421 (87% in USA; 13% outside USA)
Adult (mean age=40)
Examine the frequency with which e-cigarette users transition between device types and identify device characteristics and user preferences that may influence such transitions
  • Most e-cigarette users began use with a device shaped like a cigarette (first-generation devices) and transitioned to a larger advanced generation device with a more powerful battery and a wider choice of liquid flavours

  • Advanced generation device e-cigarette users report the variety of flavours as being important characteristic of e-cigarettes

  • Cigarettes

 Agaku et al,38 2014 (EU)N=26 566
Youth, young adults (15–24), adults (25+)
Users, non-users
Assess the role of cigarette design and marketing characteristics in initial smoking, cigarette brand choice and the perception of reduced harm of cigarette brands
  • Few ever smokers reported specific flavours as being important in their initial smoking, but flavours were significantly associated with initial smoking in younger smokers

  • Current smokers, particularly female smokers, reported specific flavours as important in their cigarette brand preference

 Ashare et al,39 2007 (USA)N=424
Young adult (mean age=19)
Users, non-users
Determine the appeal of flavoured and non-flavoured cigarettes among college student non-smokers, regular smokers and those susceptible to smoking
  • Positive and negative expectancies were influenced by flavour, with higher positive and lower negative expectancies for flavoured cigarettes compared with non-flavoured cigarettes. Positive expectancies significantly predicted the likelihood of trying flavoured cigarettes

 Doxey and Hammond,40 2011 (Canada)N=826
Youth (18–19), female
Users, non-users
Examine the effects of cigarette brand descriptors, brand colour and imagery, as well as the impact of plain or standardised packaging on young female's beliefs about smoking
  • No differences were observed between cigarette packs with and without flavour descriptors in ratings of tar delivery and health risk, though participants rated packs with flavour descriptors as better tasting and more appealing

 Hammond et al,41 2011 (USA)N=826
Youth (18–19), female
Users, non-users
Examine the effects of cigarette brand descriptors, brand colour and imagery, as well as the impact of plain or standardised packaging on young female's beliefs about smoking
  • Fully branded cigarette packs with flavour descriptors were rated as better tasting than the same packs without flavour descriptors

 Hammond et al,42 2013 (UK)N=947
Youth (16–19), female
Users, non-users
Examine the effects of cigarette brand descriptors, brand colour and imagery, as well as the impact of plain or standardised packaging on young female's beliefs about smoking
  • Removing flavour descriptors from cigarette packs significantly reduced measures of appeal and taste and increased measures of health risk

 Kaleta et al,43 2014 (Poland)N=2254
Adult (15+)
Examine whether the use of flavoured cigarettes varies by sociodemographic characteristics, awareness of the smoking health consequences and the perception of risk of use compared with regular cigarettes from current smokers
  • Flavoured cigarette use was associated with not intending to quit among females but not among males

 Manning et al,44 2009 (USA)N=253
Youth (mean age=15.7)
Users, non-users
Examine the interactive effects of cigarette package flavour descriptors and sensation seeking on adolescents’ brand perceptions
  • Among high sensation-seeking adolescents, the flavour descriptors led to more favourable hedonic brand beliefs and higher trial intentions than the traditional descriptors

 O'Connor et al,45 2007 (USA)N=20
Young adult (18–30), male
Explore differences in puff topography and cigarette ratings between flavoured and unflavoured Camels among college student smokers
  • Preference and ratings of harshness/irritation were not related to whether the cigarette brand was flavoured

 Thrasher et al,21 2016 (USA, Mexico, Australia)N=4154 (USA)
N=3366 (Mexico)
N=2710 (Australia)
Adult (18–64)
Assess trends, correlates of use and consumer perceptions related to product design innovation of flavour capsules in cigarette filters
  • Adults who preferred brands with flavour capsules viewed their variety of cigarettes as having better taste and to be more appealing and less harmful (except Australian smokers) than other brand varieties compared with adult smokers of regular non-flavoured cigarettes.

  • Preference for flavour capsule cigarettes (though primarily menthol varieties) has significantly risen in the past few years in Mexico and Australia, particularly among young adults

 White et al,46 2012 (Brazil)N=640
Youth and young adult (16–26), female
Users, non-users
Examine the effects of cigarette brand descriptors, brand colour and imagery, as well as the impact of plain or standardised packaging on young female's beliefs about smoking
  • The plain packs with flavour descriptors were given significantly higher appeal and taste ratings than the plain without flavour descriptor packs, though no significant differences were observed between packs in health risk ratings

  • Little cigars, cigarillos and cigars

 Delnevo et al,47 2015 (USA)N=6678
Youth (12–17), young adult (18–25), adult (26+)
Users, non-users
Examine use and preference of flavoured cigar brands among youth, young adults and adults in USA.
  • A clear preference was observed for cigar brands that produce flavoured varieties among youth, young adult, female, and black cigar smokers

  • Preference for flavoured cigars was associated with current cigarette smoking.

 Leatherdale et al,48 2011 (Canada)N=29 296
9th–12th grader
Users, non-users
Examine the prevalence of cigar, cigarillo and little cigar use and factors associated with their use among nationally representative sample of Canadian youth
  • Ever use of flavoured tobacco was associated with being a current cigar, cigarillo or little cigar smoker

 Yates et al,49 2014 (Canada)N=133
Young adult and adult users (age 19–29; mean age=23.6)
Examine the patterns, attitudes and beliefs regarding cigarillo use and couse of cigarillos and cigarettes among young adults
  • Flavour was the primary reason cited for smoking cigarillos

  • Hookah

 Dani et al,50 2015 (India)N=447
College students, users and non-users
Assess perception among young adults in a college environment towards using hookah for smoking tobacco
  • A significant difference between users and non-users was found, where more users indicated that hookah ‘contains pleasant flavors’ compared with non-users

 Salloum et al,51 2015 (USA)N=367
Adult (18+ mean age 21.9) college students, users
Measure preferences for waterpipe smoking and determine which product characteristics are most important to smokers
  • Participants preferred fruit-flavoured varieties to tobacco flavour

 Smith et al,52 2011 (USA)N=689
Youth (mean age=17.1)
Users, non-users
Examine patterns of use (eg, initiation, cessation), risk perception and psychosocial factors among users, former users and non-users of hookah among high school students
  • High school students cited flavours of the hookah as one of the reasons they believed hookah to be safer or less addictive than cigarettes

  • Smokeless tobacco

 Adkison et al,53 2014 (USA)N=1000
Youth (14–17), young adult (18–25), adult (26–65)
Users, non-users
Evaluate the association between smokeless tobacco packaging elements with knowledge of health risks and perceptions of novelty and appeal
  • The majority of respondents indicated no difference in opinions regarding health risk and appeal between smokeless tobacco product packaging with or without flavour descriptors

  • Among those who did report differences, youth and young adults were more likely to indicate the smokeless tobacco pack with the flavour descriptor as more appealing, attractive and having reduced health risks.

 Oliver et al,54 2013 (USA)N=468
Adult (18–70)
Examine the choice of brand flavour in the course of smokeless tobacco use, from initiation to regular use, in an intervention seeking population and examine whether users of flavoured smokeless tobacco products differ from non-flavoured users in their use patterns
  • A majority of respondents’ first and current choice of smokeless tobacco product was mint flavoured.

  • A significant number of respondents switched from a non-flavoured to a flavoured smokeless tobacco product

  • Bidi

 CDC,55 1999 (USA)N=642
7th–12th grader
Determine the prevalence of bidi use among urban youth
  • Few adolescents cited liking the flavour as a reason for smoking bidis rather than cigarettes

  • Various tobacco products

 Ambrose et al,56 2015 (USA)N=13 651
Youth (12–17)
Examine role of flavours in the use of various tobacco products among a nationally representative sample of US youth
  • Majority of ever-users reported the first product they used was flavoured

  • Product flavouring consistently reported as a reason for tobacco product use across all types or products

 King et al,57 2014 (USA)N=18 866
6th–12th grader
Users, non-users
Assess the prevalence and sociodemographic correlates of flavoured little cigar and flavoured cigarette smoking among US middle and high school students
  • Respondents who used flavoured cigars or cigarettes had a lower intent to quit than non-flavoured users

 Lee et al,58 2015 (US)N=24 658
6th–12th grader
Users, non-users
Assess the prevalence and concurrent use of patterns of various tobacco products and examine associated risk factors among US youth
  • The use of flavoured products was associated with multiple product use

 Minaker et al,59 2015 (Canada)N=17 396
Youth (grades 9–12), never smokers
Examines smoking susceptibility and alternative tobacco product use in Canadian youth
  • Never smokers who have ever tried ATPs, and particularly flavoured ATPs, are at significantly increased odds of being susceptible to cigarette smoking