Smoking-related gut microbiota alteration is associated with obesity and obesity-related diseases: results from two independent cohorts with sibling comparison analyses

Abstract Background Individuals who smoke exhibit lower body mass index (BMI) but face an elevated risk of obesity-related diseases. Emerging evidence suggests smoking may influence the composition of the microbiome. Thus, this study aims to investigate this paradox from the perspective of gut microbiota. Results Our findings contradict the conventional view that smoking primarily leads to weight loss. We observed a significant positive association between the smoking-related microbiota index and several obesity indicators. Longitudinal analysis revealed that smoking-related microbiota index is linked with an increased risk of diabetes, obesity-related cancers, and cardiovascular complications. Sibling comparison analyses further supported these results, demonstrating the robustness of the associations. Conclusion These findings challenge the conventional notion that smoking is merely associated with weight loss, uncovering instead that smoking-related microbiome changes significantly contribute to a higher risk of obesity and an augmented central fat distribution, ultimately leading to a higher risk of obesity-related diseases.