A review of e-cigarettes and their effects on DNA methylation in human studies.

BACKGROUND: The effects of conventional cigarette (c-cig) use on DNA methylation are well established, but the impact of electronic cigarettes (e-cigs) remains unclear. Objective: This scoping review aimed to map and synthesize available evidence regarding the effects of e-cig use on DNA methylation profiles in human studies. Methods: PubMed, Lilacs, Scopus, Web of Science and Cochrane were searched using terms related to e-cigs and DNA methylation up to April 2025. RESULTS: Seven studies were included, analyzing samples from saliva, peripheral blood, and bronchial epithelial tissue. The findings indicate that e-cig use is associated with changes in DNA methylation profiles compared to nonsmokers, with alterations observed in global methylation, specific sites, and epigenetic aging markers (GrimAge). Some methylation changes were shared with c-cig users, while others appeared unique to e-cig exposure. The heterogeneity of study designs, exposure duration, and biological samples precludes definitive conclusions regarding the magnitude and clinical relevance of these changes. CONCLUSION: E-cig use is associated with distinct alterations in DNA methylation in multiple human tissues, some of which are unique compared to conventional cigarettes. Further research is needed to clarify the long-term implications and potential health risks of these epigenetic changes.