Distinct oral microbiome profiles in substance users in the high-incidence Mizo tribal community, Northeast India

Objectives

To characterize the oral microbiome of substance users (primarily tobacco, alcohol, and opioids) compared to healthy controls in the high-incidence Mizo tribal community of Northeast India, and to examine their association with food and lifestyle habits.

Methods

Saliva samples from 53 substance users and 35 healthy controls were subjected to 16S rRNA (V3–V4 region) sequencing. Alpha and beta diversity analyses, differential abundance testing, and microbial functional prediction were conducted. Statistical analyses were corrected for multiple comparisons using false discovery rate (FDR) adjustment where applicable. Associations with food and lifestyle habits were also examined.

Results

Substance users exhibited significantly lower alpha diversity, and beta diversity analyses revealed distinct clustering between the two groups. Firmicutes_D, Actinobacteria, Rothia, and Streptococcus were more abundant in substance users, whereas Bacteroidota, Proteobacteria, Neisseria, and Prevotella were enriched in healthy controls. Functional predictions indicated upregulation of biofilm formation and xenobiotic degradation pathways in substance users. Exposure to Jhum cultivation, prenatal smoking, and consumption of fermented pork fat (saum) were correlated with microbial composition.

Conclusions

Substance use and associated environmental exposures were linked to oral microbiome dysbiosis. Certain bacterial taxa may serve as potential microbial biomarkers of substance use in this high-risk tribal population, warranting further investigation.