Smoking in the Context of Westernized Diets is Associated with a More Volatile Microbiome and Predicted Gut Function

With the growing consumption of a high-fat Westernized diet in Latin America, a similarly Westernized microbiome is becoming predominant. Such a microbiome brings associations of dysbiosis and harmful metabolic products, as well as the risk of cardiometabolic disease – symptoms also associated with cigarette smokers. It is currently unclear whether the combination of a Westernized diet and cigarette smoking results in a compounded effect on the gut microbiome. In this study, we aim to investigate the synergistic effect of smoking with high blood levels of low-density lipoprotein (LDL) on the gut microbiota composition and function. Our analysis was performed to explore this potential interaction between two causes of health concern and their implications for microbiome-influenced health. Using data from a 2018 microbiome study by de la Cuesta-Zulugala et al., our analyses show no significant changes in alpha diversity metrics between smoking & non-smoking individuals and their blood LDL levels. However, at both a taxonomic and functional level smokers’ microbiota appear significantly more affected by blood LDL than those of non-smokers, which were comparatively stable. Changes of note include significant increases in hallmark taxa of Westernization (Bacteroides and Clostridia), as well as downregulation of pathways relating to degradation of both aromatic compounds and D-glucarate. We postulate that the former may be in response to polycyclic aromatic hydrocarbons found in cigarette smoke, while the latter is implicated in regulation of blood cholesterol levels, suggesting a more complex interplay between smoking and measured blood LDL. Together, our findings suggest that smokers experience a more volatile gut microbiome that can be mediated through informed dietary choices.