The research, conducted by Jinwook Yang, Daesung Lee, and Kyenghee Kwon of Dongguk University, drew on data from the 2023 and 2024 Korea National Health and Nutrition Examination Survey, known as KNHANES. This ongoing national survey, run by the Korea Disease Control and Prevention Agency, combines health interviews, physical examinations, and laboratory measurements to build a representative picture of the Korean population. From it, the researchers assembled an analytic sample of 11,346 adults aged 19 years or older, a size large enough to detect meaningful differences across tobacco use patterns while controlling for a wide range of demographic and health-related factors.

Health literacy, the central variable of the study, refers to a person’s capacity to obtain, understand, and apply health information in everyday decisions. The researchers measured it using a ten-item self-reported instrument, with total scores of 30 or higher classified as adequate. Respondents falling below that threshold were considered to have inadequate health literacy. This kind of measurement matters because health literacy is not simply a proxy for education; it captures how well people navigate medication labels, prevention messages, and the increasingly crowded information environment surrounding newer nicotine products, where marketing claims about reduced harm can be difficult for consumers to evaluate.

To characterize tobacco use, the team classified participants into three categories: non-current users, single-product users, and multiple-product users, based on their current use of conventional cigarettes, heated tobacco products, and electronic cigarettes. They also examined two cessation behaviors: whether a participant had attempted to quit within the past year, and whether they intended to quit within the next six months. This dual focus is notable, because much of the existing literature treats smoking as a single behavior, whereas the modern nicotine market allows consumers to combine products in ways that may carry distinct risks and may respond differently to public health messaging.

The statistical approach reflected the complexity of the survey design. Because KNHANES uses a stratified, multistage sampling framework, the researchers employed complex sample multinomial and binomial logistic regression analyses, adjusting for sex, age, educational attainment, household income, survey year, perceived stress, weight status, and chronic disease status. Multinomial models were used to compare single-product and multiple-product users against non-current users, yielding relative risk ratios, while binomial models assessed the cessation outcomes. Sensitivity analyses were then conducted to test whether the findings held up under alternative assumptions, and they did, strengthening the credibility of the central results.

The headline finding is striking in its clarity. Inadequate health literacy was associated with a 24 percent higher relative likelihood of single-product tobacco use compared with non-current use, with a relative risk ratio of 1.24 and a 95 percent confidence interval of 1.09 to 1.42. The association was even stronger for multiple-product use, where the relative risk ratio rose to 1.43, with a confidence interval of 1.13 to 1.82. In practical terms, adults who struggle to understand health information were not only more likely to smoke at all; they were disproportionately likely to be layering cigarettes, heated tobacco, and e-cigarettes together, a pattern that public health experts generally view as particularly concerning because it can sustain or even deepen nicotine dependence.

Just as revealing is what the study did not find. Health literacy showed no significant association with either past-year quit attempts or the intention to quit within six months. In other words, people with lower health literacy were more likely to use tobacco, but once they were users, their motivation to quit appeared similar to that of their more literate peers. The authors interpret this as evidence that the role of health literacy differs across tobacco-related outcomes: it may shape who enters and remains in the pool of tobacco users, yet it does not by itself determine whether those users try to break free. That distinction carries real weight for policy, because it suggests the problem lies less in motivation than in the upstream conditions that foster tobacco use in the first place.

Why would limited health literacy push people toward tobacco, and toward product combinations in particular? The authors point to the mechanics of health communication. Anti-smoking campaigns, warning labels, and cessation resources all presuppose an ability to read, interpret, and act on health information. When that ability is compromised, the persuasive and protective functions of such messaging weaken. Meanwhile, newer products such as heated tobacco devices and e-cigarettes are often marketed with technical language and claims of reduced harm that require a degree of health literacy to critically assess. Consumers with inadequate literacy may be more vulnerable to such claims, and the proliferation of flavored and technologically styled devices may lower the perceived barriers to experimentation, eventually culminating in the use of several products simultaneously.

The Korean context sharpens the significance of these results. Despite decades of successful tobacco control, the decline in smoking has recently stalled, and the market share of heated tobacco products and electronic cigarettes has grown rapidly, particularly among younger adults. At the same time, a substantial proportion of Korean adults report inadequate health literacy. The convergence of these trends creates a potential feedback loop in which the populations least equipped to evaluate health information are the most exposed to a diversifying nicotine market. Because the study is cross-sectional, it cannot establish causation; it is possible that tobacco use itself, or the conditions that lead to it, also degrade health-related understanding. Still, the robustness of the associations across sensitivity analyses, and the careful adjustment for education and income, make a compelling case that health literacy is an independent marker of tobacco-related risk.

The authors conclude that tailoring tobacco-related health communication to different health literacy levels, combined with comprehensive cessation support, may contribute to more effective tobacco control. In practice, that could mean simplifying warning labels and cessation materials, deploying visual and verbal channels that do not depend on high reading proficiency, and ensuring that quitline and counseling services are accessible and comprehensible to everyone. The finding that quit intentions are not lower among those with inadequate literacy is, in a sense, encouraging: the desire to quit appears broadly shared, and the task for public health is to build an information environment and support system that meets people where they are. As nicotine products multiply and evolve, the study suggests that the fight against tobacco will increasingly be won or lost not only through taxation and regulation, but through the clarity of the messages that reach the people who need them most.

Subject of Research: The association between health literacy, tobacco use patterns, and cessation behaviors among Korean adults

Article Title: Association between health literacy, tobacco use patterns, and cessation behaviors among Korean adults: a population-based cross-sectional study

Article References: Yang, J., Lee, D., & Kwon, K. (2026). Association between health literacy, tobacco use patterns, and cessation behaviors among Korean adults: a population-based cross-sectional study. BMC Public Health. https://doi.org/10.1186/s12889-026-29786-9

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29786-9

Keywords: health literacy, tobacco use, smoking cessation, electronic cigarettes, heated tobacco products, multiple-product use, KNHANES, South Korea, public health, health communication, cross-sectional study, BMC Public Health

Researchers Satomi Odani and Takahiro Tabuchi drew on the Japan Society and New Tobacco Internet Survey, known as JASTIS, an internet panel study that has tracked tobacco behaviour annually since 2015. Their analysis combined two complementary approaches: repeated cross-sectional estimates of prevalence across 161,583 annual observations from 58,751 unique respondents, and longitudinal modelling of 93,540 consecutive-year transition pairs from 35,479 respondents. By classifying each participant into one of five mutually exclusive states — Never, Non-current, Cigarette-only, HTP-only, or Dual use — the team could trace not just how many people used heated tobacco, but how they arrived there and how long they stayed.

The headline trend is striking. Weighted prevalence of current heated tobacco use, defined as use on at least one day in the past 30 days, climbed from just 0.1 percent in 2015 to 14.9 percent in 2025. But the trajectory was anything but linear. Segmented statistical models identified 2018 as a decisive turning point: before that year, standardised prevalence grew at an annual rate of 283.4 percent, an absolute gain of 3.33 percentage points per year; after 2018, growth slowed to 5.7 percent per year, or 0.92 percentage points annually. The explosive early phase gave way to slower but stubbornly persistent expansion.

The pattern differed sharply across groups. Prevalence remained consistently higher among men than women, reaching 22.2 percent versus 7.7 percent in 2025, and it was highest among current cigarette smokers, among whom heated tobacco use hit 43.7 percent by 2025. Former smokers followed at 18.4 percent, while never smokers stayed far lower at just 1.4 percent. That gradient matters: it suggests heated tobacco has not swept through the entire population, but the fact that uptake continued among former and never smokers signals diffusion beyond the smoking population that substitution arguments would predict.

The longitudinal data reveal what was really driving growth. Among cigarette-only users, the probability of remaining in that state fell from 76.8 percent in 2016–2018 to 64.4 percent in 2019–2025, while transitions to Non-current use rose from 13.5 to 22.0 percent. Yet direct conversion to HTP-only use stayed low, at 2.1 percent before 2018 and 2.7 percent after, and movement to dual use rose only modestly from 7.6 to 11.0 percent. Crucially, these cigarette-to-HTP pathways stopped accelerating after 2018, undermining the idea that continued market growth reflected ever-faster switching.

What changed instead was persistence. Once people adopted heated tobacco, they increasingly stayed. The probability of remaining HTP-only from one year to the next jumped from 43.1 percent in the early period to 67.9 percent after 2018, while persistence in dual use rose from 44.9 to 57.0 percent. Corresponding exits into Non-current use fell dramatically, from 36.4 to 15.5 percent among HTP-only users and from 26.0 to 15.3 percent among dual users. In other words, the later market was sustained less by new converts from cigarettes and more by users who simply did not leave.

To quantify these dynamics formally, the researchers applied a Markov decomposition, reconstructing year-to-year changes in heated tobacco prevalence and splitting each annual change into four pathways: uptake from Never or Non-current states, switching from cigarettes to heated tobacco, switching back to cigarettes, and exit to Non-current use. The results are revealing. Before 2018, cigarette switching contributed more to growth than uptake from Never or Non-current states, with mean annual contributions of 1.43 versus 0.73 percentage points. After 2018, the picture inverted: the contribution from cigarette switching, though still averaging 1.56 percentage points, declined over time, while uptake from Non-current states surged from 0.34 to 1.40 percentage points annually. Even never smokers, whose individual-level transitions remained rare at 0.6 to 1.3 percent per year, made a small but persistent positive contribution.

Dual use emerged as a central finding with uncomfortable implications. Throughout the entire decade, dual use remained more prevalent than HTP-only use, reaching 8.4 percent versus 6.5 percent in 2025. This means a substantial share of heated tobacco consumers never abandoned cigarettes at all. The researchers are careful to note that this does not negate genuine declines in cigarette smoking or complete switching among some individuals — cigarette-only use did fall from 19.9 to 10.9 percent over the study period. But it does mean that population-level expansion of heated tobacco cannot be read as a proxy for harm reduction, because the product landscape expanded rather than simply shifted.

Context matters for interpreting these dynamics. Japan regulated heated tobacco differently from combustible cigarettes: they initially carried a lower tax burden, and the revised Health Promotion Act permitted their use in designated heated-tobacco-only rooms. The 2018 inflection point coincided with changes in taxation, smoke-free regulation, and market maturation, though the study design cannot attribute the shift to any single policy. The World Health Organization maintains that heated tobacco products are tobacco products and that the Framework Convention on Tobacco Control applies to them, while cautioning against unproven harm-reduction claims. Japan’s experience now stands as a cautionary case study for Western Pacific nations weighing their own regulatory approaches, from permissive South Korea to restrictive Australia.

The authors acknowledge limitations. JASTIS is an internet panel and may carry selection bias, so temporal patterns deserve more weight than exact prevalence figures. Longitudinal analyses were unweighted and conditional on consecutive-wave participation, and retained respondents skewed older and more male than those lost to follow-up. One-year transitions cannot capture multi-year trajectories, relapse, or whether dual use is temporary. Still, sensitivity analyses adjusting for time in the sample and restricting to adults aged 25 to 69 produced materially similar results. The core message survives scrutiny: heated tobacco growth in Japan was sustained by persistence, uptake from non-current users, and incomplete switching — not by cigarette substitution alone. For regulators everywhere, that distinction may prove decisive.

Subject of Research: Long-term trends and transition dynamics of heated tobacco product use in Japan from 2015 to 2025

Article Title: Trends and transition dynamics of heated tobacco product use in Japan, 2015–2025: a repeated cross-sectional and longitudinal study

Article References: Odani, S., & Tabuchi, T. (2026). Trends and transition dynamics of heated tobacco product use in Japan, 2015–2025: a repeated cross-sectional and longitudinal study. The Lancet Regional Health – Western Pacific, 75, Article 101990. https://doi.org/10.1016/j.lanwpc.2026.101990

Image Credits: AI Generated

DOI: 10.1016/j.lanwpc.2026.101990

Keywords: heated tobacco products, Japan, IQOS, tobacco control, dual use, smoking cessation, JASTIS survey, Markov decomposition, tobacco prevalence, public health, nicotine, Western Pacific