New research shows regular e-cigarette users exhibit changes in more than 3,000 genes, with certain flavours and advanced devices linked to greater disruption; experts say these are early biological signals that merit further study.
The debate around e-cigarettes and public health has evolved beyond respiratory irritation and nicotine dependence. Recent molecular research reveals that people who vape regularly display wide-ranging shifts in cellular activity: more than 3,000 genes showed altered functioning in a comparison between vapers and non-users.
While the results do not establish causation, they highlight how inhaling heated e-liquids can produce chemical exposures that alter gene expression patterns associated with cancer and other chronic diseases.
Researchers sampled cells from the inside of participants’ cheeks and used RNA sequencing to measure activity across thousands of genes.
The differences were not uniform: patterns varied by user group and by specific product characteristics. Importantly, many altered genes were linked to pathways involved in cancer development, endocrine function, digestion and neurological processes, suggesting a broad biological footprint tied to vaping.
What the study measured and found
The study compared 83 individuals across three groups: current vapers, cigarette smokers and people who neither smoked nor vaped. Using RNA sequencing of cheek cells, investigators detected altered expression in 3,124 genes among vapers compared with non-users. In molecular biology terms, altered expression refers to changes in the level at which genes produce RNA and, ultimately, proteins that control cell behavior. Such shifts can indicate cellular stress or disrupted repair mechanisms, both of which can contribute to long-term disease processes.
Beyond the raw count of genes, an unexpected finding was that vapers showed greater variability in gene activity than smokers. This suggests that vaping may generate more heterogeneous biological responses, which could make predicting long-term outcomes more complicated for public health monitoring.
Flavours and devices matter: patterns of disruption
One of the study’s most striking conclusions was that product characteristics — not just frequency of use — accounted for a large share of the genetic changes. Almost two-thirds of the altered gene activity correlated with the type of e-liquid flavour or the kind of vaping device. Specifically, fruit flavours and the practice of mixing different flavours were associated with the biggest shifts in gene activity. Advanced refillable units, commonly called mods, were also linked to stronger molecular effects than simpler disposables or closed systems.
To quantify the pattern: fruit flavours corresponded to changes in about 31% of affected genes, while using multiple flavours related to changes in roughly 64.3% of those genes. Sweeter flavour categories accounted for a smaller portion, and mint/menthol even less. These associations point toward the chemical composition of flavourings and the thermal behavior of different devices as plausible drivers of biological impact.
Chemical mechanisms and regulatory implications
Heating e-liquids produces a complex mixture of chemicals. Some compounds, even at low concentrations, can provoke inflammation or interact with DNA repair pathways, altering normal cellular maintenance. The research team emphasized the importance of identifying which specific additives or thermal byproducts are responsible for the observed gene changes. Pinpointing causative chemicals could guide targeted regulation, for example by restricting certain flavouring agents or mandating formulation changes to reduce harmful byproducts.
Interpreting the health signals
Experts caution that the study is observational and relatively small, so it cannot prove that vaping causes cancer or specific chronic illnesses. Instead, the altered gene activity should be seen as an early biological signal — a molecular fingerprint that may precede disease if exposures continue. Smoking still carries the highest risk for many conditions, including lung cancer and chronic obstructive pulmonary disease, but these findings suggest vaping could also contribute to future disease burden if harmful exposures persist across populations.
Next steps for research and policy
Future studies need larger cohorts, longer follow-up and direct chemical assessments to link specific e-liquid components to the molecular changes. Animal and cell models can help establish mechanisms, while population monitoring can track whether these early signals correspond to rising rates of head, neck, or other cancers. Regulators face pressure to act, especially to reduce youth uptake. Some jurisdictions have already restricted disposable or flavored products as part of those efforts.
In the meantime, scientists recommend continued caution. While vaping is often promoted as a tool to quit smoking and is generally considered less harmful than combustible tobacco, it is not without potential risks. The discovery of widespread changes in gene expression tied to flavours and device types reinforces the need for careful product oversight and more comprehensive research to protect public health.
