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. Author manuscript; available in PMC: 2023 Feb 1.
Published in final edited form as: Addict Behav. 2021 Oct 30;125:107168. doi: 10.1016/j.addbeh.2021.107168

Preferred Flavors and Tobacco Use Patterns in Adult Dual Users of Cigarettes and ENDS

Eva C Rest 1, Kristin N Brikmanis 1,2, Robin J Mermelstein 1,2
PMCID: PMC8629959  NIHMSID: NIHMS1752858  PMID: 34772504

Abstract

Objectives:

This study examined how adult dual users of cigarettes and electronic nicotine delivery system (ENDS) flavor preference varied by demographics, tobacco history, motives, and expectancies for ENDS, and how ENDS flavor preference was associated with changes in cigarette and ENDS use over 12 months.

Methods:

Data come from the baseline and 12-month waves of an observational study of adult dual cigarette and ENDS users (N = 406). Flavor preferences were grouped into 4 categories: tobacco (12.6%), menthol/mint (34.7%), sweet (44.8%), and other (7.9%).

Results:

Users of sweet-flavored ENDS were significantly younger than those who used tobacco- or menthol flavors. Black dual users were significantly more likely than other racial groups to use menthol and less likely to use sweet flavors. Dual users who preferred sweet flavors smoked cigarettes on fewer days than those who preferred tobacco and menthol flavors, were less cigarette dependent, more strongly endorsed boredom reduction expectancies and motives related to taste and sensory experience and were more likely to stop smoking by 12 months.

Conclusions:

Dual users of cigarettes and ENDS who preferred sweet flavored ENDS differed in demographics, tobacco history, motives, expectancies, and smoking changes. Findings have implications for interventions and regulations.

Keywords: e-cigarettes, flavors, dual users of cigarettes and ENDS

1.0. Introduction

While combustible cigarette smoking has been declining in the United States, use of electronic nicotine delivery systems (ENDS) has emerged as the most common dual tobacco product use combination among cigarette smokers.1 The class of ENDS includes e-cigarettes, vaporizers, and other products in which a solution containing varied levels of nicotine and characterizing flavorings is heated to create an inhalable aerosol. Given evidence that ENDS are less harmful than combustible cigarettes, there is potential for reducing combustible-related harms if adult smokers are able to switch completely from cigarettes to ENDS.2–5 However, there is also concern that ENDS use is becoming increasingly common among youth, and its use may serve as a catalyst to combustible tobacco use initiation.2,6,7

Product characteristics, such as flavors, further complicate the debate as to whether the potential benefits of ENDS for harm reduction outweigh the potential risks of tobacco use initiation at the population-level. One of the most frequently reported reasons for using ENDS is the availability of appealing flavors.8–11 There are a multitude of unique ENDS flavor options, and researchers have suggested classifying them into 13 main categories: tobacco, menthol/mint, fruit, dessert, candy, other sweets, nuts, spices, coffee/tea, alcohol, other beverages, other flavors, and unflavored e-liquids.12,13 Sweet flavors like fruit, candy, and dessert tend to be the most commonly used nontobacco and nonmenthol flavors.14,15 While nontobacco flavors, including menthol and sweet flavors, may make ENDS more appealing to adult smokers as a substitute for combustible tobacco products, there is concern that nontobacco flavors also make ENDS more attractive to adolescent and young adult nonsmokers.16,17

Under the Family Smoking Prevention and Tobacco Act and the 2016 Deeming Rule, the U.S. Food and Drug Administration (FDA) has the power to regulate ENDS product standards, including characterizing flavors, with the goal of reducing the net risk of harm to public health.16 In 2009, the FDA banned all characterizing flavors in cigarettes other than menthol, but flavors of other tobacco products remain largely unregulated.18 Presently, FDA regulation of ENDS flavors differs by ENDS product; the FDA has restricted the sale of flavored ENDS in stores and enacted a modified ban on flavored ENDS cartridges, although non-cartridge e-juice does not share the same flavor restrictions.19 However, the regulatory space is changing quickly and contains exceptions that may promote switching to other, unregulated flavored products. Little is known about who uses each ENDS flavor category. Understanding how user characteristics such as age, sex, race, tobacco use history, nicotine dependence, motives, and expectancies for ENDS differ by flavor preference could help inform upcoming regulatory decisions regarding ENDS flavors.

To date, the most extensively studied correlate of ENDS flavor preference is user age. Previous studies have found that younger ENDS users are more likely to prefer nontobacco flavors and less likely to prefer tobacco flavors compared to older users, who may be more likely to prefer menthol compared to younger adults.8,15,20 Findings specific to fruit flavors are mixed, with one study reporting an inverse association and another reporting no association.8,15

Few studies have examined how other user characteristics relate to ENDS flavor preference. Findings regarding differences in flavor preference by sex are mixed. Studies suggest women may be more likely than men to prefer nontobacco and nonmenthol flavors.21–24 However, other studies have not observed differences by sex.8,15,25 In terms of race and ethnicity, Black ENDS users may be more likely to use menthol flavored ENDS and less likely to use fruit flavored ENDS.8,26 ENDS users who have completed high school may be more likely to use nontobacco and nonmenthol flavors.21 Better understanding how flavor preference correlates with user characteristics may be important in regulating flavors and predicting potential impacts of such regulation.

Little is known about how flavor relates to ENDS use and dependence. Initial evidence suggests longer-term ENDS users and those who use ENDS more frequently may prefer nontobacco flavors.9,23,27,28 Rodent and human laboratory behavioral pharmacology experiments support that risk of dependence may differ by ENDS flavor used. Rodent models have indicated that nicotine enhances the reinforcing value of sweeteners found in ENDS flavors.29 Given these synergistic effects, use of sweet-flavored ENDS could result in greater dependence risk or abuse liability relative to non-sweet flavored ENDS.

Reported subjective effects, behavioral choice task outcomes, and observed self-administration behaviors from human studies are consistent with this notion. Sweet ENDS flavors have been associated with greater satisfaction, liking, and tasting, relative to flavorless and tobacco, menthol, and mint flavors.25,30–32 Menthol flavored ENDS also have been associated with greater liking, wanting, and positive physical sensations, relative to unflavored ENDS.33,34 In 2 choice tasks, young adults perceived sweet flavored ENDS as worth more money, worked harder for them, and took more puffs of sweet flavored ENDS than unflavored ENDS.31,32

Despite concerns that users of nontobacco flavored ENDS may be particularly susceptible to nicotine dependence and increased use of ENDS and combustible tobacco products, little is known about how tobacco use patterns over time may differ by use of ENDS flavor preference. Associations have also been found between ENDS flavor preference and cigarette smoking status, such that nonsmokers tend to prefer nontobacco flavored ENDS.14,15,35 To our knowledge, naturalistic studies have not observed how ENDS flavor preferences relate to ENDS and cigarette use over time, and only one experimental study has addressed this question. Among adult cigarette smokers without an intention to quit, those who agreed to try substituting ENDS for cigarettes and were assigned chocolate flavored e-cigarettes used e-cigarettes the least intensely and reduced their cigarette use the least, compared to those assigned to cherry, tobacco, and menthol.36 Those who used menthol flavored e-cigarettes, showed the largest decrease in cigarettes per day, and e-cigarettes per day was highest among those who used tobacco flavored e-cigarettes.36

1.1. Current Study

The present study focused on adult dual users—individuals who use both combustible cigarettes and ENDS— and their use of tobacco, menthol, sweet, or other flavored ENDS. Given the increasing prevalence of dual use among combustible cigarette smokers, our interest was in understanding more about changes in patterns of these dual users and factors that might influence changes in patterns. Dual use can be a temporary use pattern, so associations between flavor preference and sustained dual use, smoking cessation, or ENDS rejection may be important in improving health outcomes.37 Although ENDS-only users are an important population to study as well, they were not included within the scope of the present study. We examined how dual users’ characteristics (demographics, tobacco use, dependence, motives, and expectancies for ENDS use) differed by their preferred ENDS flavor. We also observed how ENDS flavor preference related to use of cigarettes and ENDS over 12 months. We hypothesized that younger users, women, lighter cigarette smokers, and heavier ENDS users would be more likely to prefer sweet-flavored ENDS than tobacco and menthol flavors. We expected that Black users and those whose regular brand of cigarettes was menthol flavored to prefer menthol flavored ENDS. We also hypothesized that those who preferred nontobacco flavors would more strongly endorse motives related to taste and sensory experience. Finally, we expected ENDS use would escalate more quickly over time among those who preferred nontobacco flavored ENDS.

2.0. METHODS

2.1. Participants

Participants (N = 406; 40% women) were adult (M = 34.6 years of age, SD = 12.6) dual cigarette and ENDS users who were recruited as part of an observational longitudinal study of cigarette and ENDS use patterns. Approximately 12% identified as Hispanic or Latino; 48% identified as White; 34% as Black or African American; 12% as Asian; and 12% as American Indian, Native Alaskan, Native Hawaiian, or multiracial. Eligible participants were Chicago area residents aged 18 or older, had smoked combustible cigarettes at least weekly in the past 30 days, had used ENDS at least once in the past 14 days, and indicated intention to continue ENDS use in the near future. Intention to continue to use ENDS was assessed with the questions: “how likely are you to use an e-cigarette/nicotine vaporizer in the next 2 weeks?” and “how likely are you to purchase an e-cigarette/nicotine vaporizer in the next 2 weeks?” Responses of “moderately likely” or “very likely” indicated intention to continue ENDS use. Those who were unable to speak and read English and those not willing or able to complete the baseline questionnaire and carry an ecological momentary assessment (EMA) device for 7 days were excluded.

2.2. Procedures

Participants were recruited using print advertisements, online media (eg, Craigslist, Facebook), and targeted venue and snowball recruitment as part of a longitudinal study of the context and subjective experience of dual cigarette and ENDS use. Interested persons first completed an online eligibility screening survey, after which study staff contacted eligible individuals to complete a second phone screening survey. Those who were deemed eligible after the second screener and were interested in participating completed a baseline visit at the research office. Participants provided informed consent, completed baseline questionnaires including tobacco use history, current use, flavor preferences, and nicotine dependence measures. Participants received biweekly tobacco use surveys via email, beginning 2 weeks post-baseline and continuing for 12 months. At 12 months, participants completed a questionnaire of their current tobacco use, dependence, and attitudes to reflect change over time from baseline. The current study focuses on data from the baseline and 12-month questionnaires. All procedures were approved by the University of Illinois Chicago Institutional Review Board. Data were collected from October 2016 to October 2019.

2.3. Measures

Demographic variables assessed at baseline included age, sex, highest level of education attained, race, and ethnicity. Participants reported the frequency (number of days) and rate (number of cigarettes or sessions per day) they used cigarettes and ENDS in the past 7 and 30 days at baseline and 12 months. At baseline, participants reported whether their regular brand of cigarettes was menthol flavored and indicated from a list of flavors typically found in ENDS products what their preferred e-liquid was flavored to taste like. Participants also were given the option to choose ‘other’ and manually enter their preferred flavor; these responses were reviewed by study staff and recategorized when applicable. For ease of analysis, this item was collapsed into a variable reflecting tobacco flavored ENDS (12.6%), menthol/mint (34.7%), sweet flavors (44.8%), and other flavors (7.9%). Sweet flavors included dessert, fruit, and candy, and other flavors included spice/clove, alcohol, and coffee/tea. At baseline, participants reported whether the ENDS device they usually used was disposable, rechargeable with a pre-filled cartridge, or rechargeable with a refillable cartridge. At baseline, participants reported if they had ever used ENDS to help quit cigarettes.

The Nicotine Dependence Syndrome Scale (NDSS) and a 14-item version of the Brief Wisconsin Inventory Smoking Dependence Motives (WISDM) were used to assess nicotine dependence for cigarettes.38–40 These scales were modified to assess nicotine dependence for ENDS by changing the wording about cigarettes to reflect ENDS use. Scales modified by similar methods have shown good reliability and validity for assessing e-cigarette dependence.41 Internal consistency was good for the ENDS (α = 0.93) and cigarette (α = 0.91) WISDM scales, as well as the ENDS (α = 0.91) and cigarette (α = 0.89) NDSS scales. A 10-item scale was used to assess Expectancies for smoking cigarettes were assessed with a 10-item, 4-point Likert scale, with higher scores indicated more positive expectancies. This scale was modified, by substituting cigarette for ENDS, to assess expectancies for using ENDS. Internal consistency was good for both the ENDS (α = 0.89) and cigarette (α = 0.81) scales.

2.4. Analytic Approach

ANOVAs and chi-squared tests were used to examine whether user characteristics and attitudes (demographics, tobacco use, dependence, motives, and expectancies) differed by e-cigarette flavor preference (tobacco, menthol, sweet, and other). Repeated measures ANOVAs were used to examine whether e-cigarette flavor preference was associated with differences in cigarette and ENDS use frequency at baseline and 12 months. To account for multiple comparisons, a Bonferroni correction was used for all post hoc pairwise comparisons.

3.0. RESULTS

3.1. User Characteristics By ENDS Flavors

Table 1 shows user characteristics by ENDS flavor preference. Overall, sweet flavors were most frequently preferred by participants (44.8%), followed by menthol/mint (34.7%), tobacco (12.6%), and other (7.9%). ENDS flavor preference differed significantly by participant age (F(3, 402) = 23.56, p < .001) and race (χ2(9) = 54.42, p < .001). Those who reported preferences for sweet and other flavored ENDS were younger than those who reported preferences for tobacco and menthol flavored ENDS. Black dual users were more likely to prefer menthol flavored ENDS and less likely to prefer sweet-flavored ENDS. No other significant differences in demographics by ENDS flavor preference were observed.

Table 1.

Descriptive Statistics for Baseline User Characteristics by ENDS Flavor Preference

Flavor Preference
Total Sample (N = 406) Tobacco (N = 51; 12.6%) Menthol/Mint (N = 141; 34.7%) Sweet (N = 182; 44.8%) Other (N = 32; 7.9%)
Age, M (SD) ** 34.6 (12.6) 39.1 (12.1)a 40.2 (13.2)a 29.9 (10.6)b 31.3 (10.2)b
Sex (%)
 Female 40.2% 36.7% 44.9% 35.9% 47.4%
 Male 58.6% 59.2% 54.4% 63.0% 52.6%
 Nonbinary 1.2% 4.1% 0.7% 1.1% 0%
Hispanic or Latino (%) 12.3% 10.2% 12.9% 13.3% 8.3%
Race (%) **
 White 48.3% 61.2% 29.7% 60.8% 39.5%
 Black 33.7% 24.5% 55.8% 19.3% 34.2%
 Asian 11.6% 10.2% 9.4% 12.7% 15.8%
 Other 6.4% 4.1% 5.1% 7.2% 15.4%
Education (%)
 Some high school 6.4% 4.1% 10.1% 3.3% 10.5%
 High school graduate 19.2% 10.2% 23.9% 18.8% 15.8%
 Some college 50.2% 51.0% 46.4% 53.6% 47.4%
 4-year college graduate 24.1% 34.7% 19.6% 24.3% 26.3%
Prefer menthol flavored cigarettes (%) ** 60.2% 24.5%a 89.1%b 49.7%c 52.6%c
ENDS device type (%) **
 Disposable 18.5% 34.7% 23.9% 8.8% 23.7%
 Rechargeable with a pre-filled cartridge 29.6% 23.9% 46.4% 17.7% 18.4%
 Rechargeable with a refillable cartridge 51.9% 28.6% 29.7% 73.5% 57.9%
ENDS use days, M (SD)
 Past 30-day 14.7 (11.0) 14.8 (10.5) 13.2 (10.9) 16.0 (11.1) 14.1 (11.6)
 Past 7-day 3.5 (2.8) 3.0 (2.5) 3.3 (2.7) 3.8 (2.9) 3.3 (2.9)
Cigarette use days, M(SD)
 Past 30-day** 25.2 (7.9) 26.8 (6.1)ab 26.5 (7.2)a 23.6 (8.6)b 25.8 (8.0)ab
 Past 7-day** 5.8 (2.1) 6.2 (1.8)ab 6.2 (1.7)a 5.4 (2.2)b 5.9 (2.3)ab
Cigarettes/day, M(SD)
 Past 30-day** 8.2 (7.2) 9.9 (6.8)a 9.4 (8.0)a 7.0 (6.7)b 7.4 (5.3)
 Past 7-day** 8.5 (8.3) 9.2 (6.7)a 9.8 (8.8)a 6.7 (6.6)b 11.2 (13.5)
ENDS NDSS, M (SD) 2.1 (1.0) 2.1 (1.1) 2.1 (1.0) 2.0 (0.9) 2.1 (1.1)
Cigarette NDSS, M (SD) ** 2.9 (1.0) 3.0 (0.8)ab 3.0 (1.0)a 2.7 (1.0)b 3.2 (1.1)a
ENDS WISDM, M (SD)
 Affective enhancement 3.4 (1.9) 3.8 (1.8) 3.3 (1.9) 3.4 (1.9) 3.4 (2.0)
 Automaticity 3.6 (2.2) 3.0 (2.1) 3.4 (2.2) 3.8 (2.2) 3.9 (2.4)
 Cognitive enhancement 2.9 (1.8) 3.6 (2.1) 2.8 (1.9) 3.1 (1.9) 3.0 (2.1)
 Craving 2.9 (1.8) 2.9 (1.7) 3.1 (1.9) 2.9 (2.9) 2.9 (2.0)
 Loss of control 1.9 (1.4) 1.8 (1.3) 1.9 (1.4) 1.9 (1.3) 2.1 (1.7)
 Taste/sensory experience** 5.2 (1.8) 4.6 (1.7)a 4.7 (1.9)a 5.6 (1.6)b 5.1 (1.9)ab
 Tolerance 2.9 (2.0) 2.6 (1.9) 2.8 (1.9) 3.0 (2.0) 2.8 (2.0)
Ever used ENDS to try to quit cigarettes (%) 78.6% 81.7% 81.3% 74.6% 84.2%
ENDS expectancies
 Boredom reduction** 2.7 (1.0) 2.6 (1.0)ab 2.4 (1.0)a 3.0 (1.0)b 2.6 (1.0)ab
 Negative reinforcement 2.4 (1.0) 2.6 (1.0) 2.4 (1.0) 2.3 (0.9) 2.2 (1.0)
 Weight control 1.6 (0.8) 1.8 (0.8) 1.6 (0.8) 1.6 (0.8) 1.7 (1.0)
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Note: Items within a row that share the same superscript letter do not significantly differ from each other. ENDS = electronic nicotine delivery systems. NDSS = Nicotine Dependence Syndrome Scale. ‘Other’ race includes ‘American Indian/Native Alaskan,’ ‘Native Hawaiian/Pacific Islander,’ and those who selected more than one race.

*

= p < .05

**

= p < .01.

Tobacco use and dependence also varied by flavor preference at baseline (Table 1). Dual users who preferred sweet flavored ENDS used cigarettes less frequently in the past month (F(3,402) = 4.58, p < .004) and past 7 days (F(3, 402) = 4.40, p < .005) than those who preferred menthol flavored ENDS, and also had lower daily rates of cigarette use for both past month (F(3, 402) = 4.24, p < .006) and past 7 days (F(3, 402) = 5.31, p < .002). However, frequency of ENDS use during the past month or during the past 7 days did not vary by ENDS flavor preference (F(3, 402) = 2.46, p = .07 for past month; and F(3, 402) = 1.46, ns for past 7 days). Daily rate (sessions per day) of ENDS use also did not vary significantly by flavor choice. Dual users who preferred sweet flavored ENDS had significantly lower cigarette nicotine dependence scores than users who preferred non-sweet flavored ENDS (F(3, 402) = 5.26, p = .001). ENDS nicotine dependence measures did not differ by ENDS flavor preference (F(3, 400) = 0.06, ns).

Participants’ usual cigarette brand flavor (χ2(3) = 82.91, p < .001) and ENDS device (χ2(6)= 77.78, p < .001) were also related to ENDS flavor preference. Of the 60.2% of participants who primarily used menthol cigarettes, participants were more likely to prefer menthol flavored ENDS (89.1%) than sweet (49.7%) and other flavored ENDS (52.6%), which were preferred relative to tobacco flavored ENDS. Those who typically used rechargeable ENDS devices with pre-filled e-liquid cartridges were more likely to use menthol/mint flavors, while those who typically used rechargeable ENDS devices with refillable e-liquid cartridges were more likely to use sweet and other flavors (Table 1).

Dual users who preferred sweet-flavored ENDS also differed significantly from those who preferred menthol flavors in their motives and expectancies for use. Those who preferred sweet flavored ENDS endorsed higher boredom reduction expectancies (F(3, 401) = 6.90, p < .001) and dependence motives related to taste and sensory experience (F(3, 398) = 8.74, p < .001) compared to those who preferred menthol flavor. Flavor preference was unrelated to having ever tried to use ENDS to help quit cigarettes (χ2(3) = 3.31, p = .346). No other significant differences in ENDS dependence motives and expectancies by ENDS flavor preference were observed.

3.2. 4.0 Changes In Cigarette And ENDS Use Frequency Over 12 Months

We examined the association between flavor preference and changes in cigarette and ENDS use frequency (past 30-day frequency) over 12 months using repeated measures ANOVA. Of the 406 participants with baseline data, 364 (89.4%) completed the 12-month questionnaire and were included in these analyses. Those who were missing, compared to those who were included in the analyses, did not differ significantly at baseline in terms of age, race, sex, frequency of either cigarette or ENDS use, or cigarette or ENDS dependence. Table 2 shows the mean frequency (use in past 30 days) for cigarettes and ENDS at both baseline and 12 months by baseline flavor preference for participants with data at both time points. Frequency of use for both cigarettes and ENDS decreased significantly over time. The repeated measures ANOVA examining changes in cigarette frequency from baseline to 12 months found a significant effect for time (F(1, 357) = 113.5, p < .001) and for the time X ENDS flavor group (F(3, 357) = 6.00, p < .001). All ENDS flavor groups decreased their frequency of cigarette smoking over time, but the reductions for the sweet flavor preference group were significantly larger than those for the menthol flavored group (F(3, 357) = 6.00, p < .001). The changes over time in frequency of ENDS use, however, were less notable and similar across flavor preference groups. The repeated measures ANOVA examining changes in ENDS use over time found a significant effect for time (F(1,3) = 6.97, p < .01), but no significant time X ENDS flavor group interaction (F(1,3) = 0.34, ns).

Table 2.

Descriptive Statistics for Cigarette and ENDS Use Over Time by ENDS Flavor Preference.

Total Sample (N = 364) Tobacco (N = 43) Menthol/Mint (N = 131) Sweet (N = 160) Other (N = 27)
ENDS use days, M (SD)
 Baseline 14.7 (11.0) 14.8 (10.5) 13.2 (10.9) 16.0 (11.1) 14.1 (11.6)
 12 months 13.0 (12.3) 11.3 (11.7) 11.7 (11.6) 14.6 (12.9) 12.0 (12.1)
Cigarette use days, M (SD)
 Baseline 25.2 (8.0) 27.5 (4.9) 26.7 (7.2) 23.6 (8.7) 24.6 (8.9)
 12 months 19.2 (12.5) 20.6 (11.9) 23.4 (10.6) 15.2 (12.9) 20.7 (12.5)
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Sample restricted to participants who had both baseline and 12-month follow-up data.

At 12 months, 16.1% (N = 58) of participants reported no cigarette smoking in the past 30 days, and flavor preference was significantly associated with cigarette abstinence at 12 months (χ2(3) = 23.41, p < .001). Participants who preferred sweet flavored ENDS were significantly more likely to report no smoking in the past 30 days (23.7%, N = 38) compared to the other flavor groups (16.3% quit among tobacco flavor preference; 6.9% quit among menthol flavor preference; 14.8% quit among other flavor preference). In terms of ENDS cessation, 86 participants (23.8%) reported no ENDS use over the past 30 days at 12 months. There were no significant differences in ENDS quit rate by flavor preference (χ2(3) = 2.25, ns). Only 11 participants (3.0%) reported no use of both ENDS and cigarettes for the past 30 days at 12 months, with no significant difference by ENDS flavor preference.

4.0. DISCUSSION

The present study examined how characteristics of adult dual users of cigarettes and ENDS differed by their preferred ENDS flavor and the extent to which ENDS flavor preference prospectively related to cigarette and ENDS use 12 months later. ENDS flavor choice was related differentially to demographic factors, tobacco use factors, motives and expectancies for ENDS use, as well as changes in smoking over time. Consistent with previous literature, younger age was associated with a higher likelihood of reporting a preference for sweet-flavored ENDS relative to tobacco flavored ENDS and menthol flavored ENDS.8,15,42 While this finding is consistent with concerns that nontobacco flavored ENDS may be particularly attractive to younger ENDS users, it is notable that sweet flavors were the most frequently preferred flavor choice, regardless of age.16,17

Individuals whose regular cigarette brand was menthol flavored were more likely to report a preference for menthol flavored ENDS and less likely to report a preference for sweet-flavored ENDS. Not surprisingly, then, Black dual users were more likely to report a preference for menthol flavored ENDS and less likely to report a preference for sweet-flavored ENDS. In recent years, even as the overall smoking rate in the U.S. declines, the proportion of menthol-using smokers has significantly increased.43 Thus, regulations on ENDS flavors that include bans or limitations on menthol/mint flavors may disproportionately affect Black smokers.8,18,26,44 The harm reduction potential of ENDS may be particularly important for Black smokers who are disproportionately more likely to die from smoking-related illnesses than White smokers and less likely to successfully quit smoking.45–47 These harm reduction effects may even extend beyond individual smokers, as Black communities are most impacted by secondhand cigarette smoke.48 Policy makers will need to consider how a flavor ban may disproportionately affect Black smokers when balancing the potential benefits from ENDS use for harm reduction with the potential dangers of introducing naïve users to nicotine dependence. Other factors that may play into this consideration are that Blacks are more likely to initiate smoking at a later age than White smokers, and Black adolescents are less likely to have ever used or currently use ENDS than peers of other racial backgrounds.49,50 Thus, harm reduction via ENDS use may be a more relevant issue in Black communities than preventing naive ENDS use. While menthol cigarettes remain legal and easily accessible, menthol/mint flavored ENDS may retain their importance as a harm reduction alternative. Further research is needed on the long-term health effects of menthol flavored ENDS products and use of menthol flavored ENDS as a successful cessation tool compared with other ENDS flavors.

In terms of tobacco use history, individuals who endorsed less frequent cigarette use and weaker cigarette dependence were more likely to report preferences for sweet-flavored ENDS, which may also be a function of younger age and shorter history of tobacco use. ENDS use and dependence did not differ by ENDS flavor preference.

Motives and expectancies for ENDS use also differed by flavor. Unsurprisingly, preference for sweet- flavored ENDS was associated with more strongly endorsing taste and sensory experience as motives for using ENDS. Preferring sweet flavored ENDS was also associated with more strongly endorsing expectancies that ENDS use reduces boredom. It may be that sweet flavored ENDS users are more likely to expect ENDS to increase positive affect or that younger ENDS users, who represent the largest group of sweet flavored ENDS users, may be more likely to expect ENDS will reduce their boredom. Endorsement of ever use of ENDS to try to quit cigarettes did not differ by ENDS flavor preference.

Cigarette and ENDS use frequency declined significantly over 12 months for all ENDS flavor groups. However, declines in cigarette use frequency were significantly greater for sweet-flavored ENDS users than for menthol flavored ENDS users. A notable proportion of the dual users reported no smoking in the past 30 days at 12 months, and dual users who preferred sweet flavored ENDS were the most likely to quit smoking. Changes in the frequency of ENDS use over time did not vary by flavor group, and stopping ENDS use was not associated with flavor preference.

Strengths of the present study include the focus on adult dual cigarette and ENDS users, the size and racial diversity of the sample, and the inclusion of a variety of measures of tobacco use, dependence, and related factors over time. The present study also has limitations. Preferred ENDS flavors may not be representative of the individuals ‘actual use of ENDS flavors. The 12 month period of ENDS and cigarette use captured by this study does not reflect initiation and may reflect a relatively short period of tobacco use. User characteristics and ENDS flavor preference were assessed cross-sectionally and may have changed over time, precluding examination of any temporal relationship between ENDS flavor preference and user characteristics, such as ENDS use expectancies.

Findings from the present study suggest that dual users who prefer sweet-flavored ENDS may be a distinct subset of ENDS users who differ in all of the examined domains: demographics, tobacco use history, motives, and expectancies. These data also suggest that individuals who prefer sweet flavor ENDS may be most likely to reduce cigarette smoking over time and potentially to stop smoking. This is consistent with other research indicating use of ENDS, particularly non-tobacco flavored ENDS, is positively associated with smoking cessation in adult smokers.51 Future analysis that controls for factors like tobacco use history and baseline ENDS use would offer important insight into the relationships between preferred ENDS flavors, age, and likelihood of cessation. Additional research is needed to better understand the role of ENDS flavors in determining tobacco use and dependence as well as their impact on tobacco-related risks.

5.0. CONCLUSIONS AND IMPLICATIONS FOR TOBACCO REGULATION

The question of how to regulate flavored ENDS products to promote smoking cessation and reduce initiation of naïve use is complex and multifactorial. Research has shown sweet flavored ENDS are preferred by never smokers, current smokers, and former smokers compared to tobacco or menthol flavored ENDS.52 This may be due to the flavored e-liquid suppressing the negative or aversive effects of nicotine or making the consumption of e-liquids higher in nicotine concentration more palatable.2,17,52 Sweet flavored ENDS are also perceived as less harmful by some users, which may lead to increased use or nicotine dependence.2,53,54 In our study the majority of dual users preferred sweet flavored ENDS, regardless of age. This finding supports previous research suggesting that poly-tobacco users are more likely to use a flavored product than single-product tobacco users.55,56 Furthermore, use of non-tobacco flavored ENDS is positively associated with smoking cessation in adult smokers, but not significantly associated with young people initiating cigarette smoking.51 However, studies specifying different types of non-tobacco ENDS flavors have found varying results. In one study, adult smokers using menthol flavored ENDS reduced their cigarette use significantly more than adult smokers using fruit flavored ENDS.36 In other studies, former smokers who switched to sole ENDS use preferred sweet flavors, while smokers who maintained dual use were more likely to use tobacco or menthol flavored ENDS.52,57 A ban on ENDS flavors may discourage dual use or cessation attempts, especially if ENDS are taxed similarly to cigarettes. A simultaneous policy solution that affects both cigarettes and ENDS may be important, such that ENDS remain an attractive switching option for current smokers, but become less attractive to naïve users as price increases or accessibility becomes more difficult.

A distinction should be made between sweet-flavored e-liquid and other e-liquid flavors, since dual users who prefer sweet flavors emerged as a distinct group in terms of age, tobacco use history, expectancies, and motives for use. Although all ENDS flavor groups decreased their cigarette use over 12 months, sweet-flavored ENDS users experienced significantly larger decreases. Regulators must carefully balance the need to prevent naïve users from initiating ENDS use with the potential harm reduction benefit of smokers to completely switch away from combustible cigarettes. Harm reduction and cessation possibilities for dual users and current smokers remain critical public health objectives, thus regulators must carefully consider health outcomes when enacting flavor restrictions.

Highlights.

  • Younger age was associated with preferring sweet vs other ENDS flavors.

  • Black dual users were more likely to prefer menthol than sweet ENDS flavors.

  • Sweet-flavored ENDS choice was associated with sensory and boredom relief motives.

  • 16.1% of dual users reported no past 30-day cigarette use at 12 months.

  • Dual users who preferred sweet-flavored ENDS were most likely to quit smoking.

Role of Funding Sources

Research reported in this publication was supported by the NCI and FDA Center for Tobacco Products (CTP) grant R01CA184681. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the Food and Drug Administration. This project utilized UIC’s installation of REDCap supported by UIC’s Center for Clinical and Translational Science (CCTS) UL1TR002003.

Footnotes

Conflict of Interest

The authors have no relevant conflicts of interest to disclose.

Author Agreement

All authors have contributed to this manuscript and have approved the final submitted version. This manuscript is the authors’ original work, has not been published elsewhere, and is not under consideration for publication elsewhere.

Author Disclosure

Human Subjects Statement

Procedures in this study were approved by the University of Illinois at Chicago Institutional Review Board.

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