Smoking and Risk of Fatty Liver Disease: A Meta-Analysis of Cohort Studies

Background/Objectives: It remains inconclusive whether or not smoking is associated with an increased risk of fatty liver disease (FLD). We investigated the association between smoking and the risk of FLD by using a meta-analysis of cohort studies. Methods: PubMed and EMBASE were searched using keywords from their inception to September 2023 to identify relevant studies. Results: Out of 806 articles searched from the databases, a total of 20 cohort studies were included in the final analysis. In the meta-analysis, smoking was significantly associated with an increased risk of FLD (odds ratio/relative risk/hazard ratio, 1.14; 95% confidence interval, 1.05–1.24; n = 20). Subgroup analyses showed a significant positive association between them in prospective cohort studies (odds ratio/relative risk/hazard ratio, 1.15; 95% confidence interval, 1.05–1.18; n = 5) but not in retrospective cohort studies and cross-sectional studies based on cohort studies. In the subgroup meta-analysis by gender in Asians, smoking significantly increased the risk of FLD in men, while there was no significant association between FLD and smoking in women. Conclusions: This meta-analysis showed that smoking increases the risk of FLD. In addition to well-known risk factors of FLD, clinicians should recommend smoking cessation for the management of FLD.