Impact of waterpipe smoking on the salivary microbiomeOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked how waterpipe (shisha) smoking changes the salivary microbiome compared with non-smoking. Researchers collected unstimulated saliva and profiled bacteria with 16S rRNA gene sequencing on the Illumina MiSeq platform. Reads were processed with DADA2. The team assessed alpha and beta diversity, used LEfSe to find differentially abundant taxa, and used MaAsLin2 and PICRUSt2 to compare predicted metabolic pathways. The design was cross-sectional, comparing smokers against matched non-smoking controls at a single time point.
Who was studied?
The cohort was 60 healthy adults in Kuala Lumpur and the Klang Valley, Malaysia, split into 30 waterpipe smokers and 30 non-smokers. All participants were male, matched for age and gender. Smokers had a mean age of 31.1 years and controls 21.5 years. Inclusion required current waterpipe use with no other smoking form, no medications in the prior 3 months, and no self-reported gum disease. Saliva from smokers was collected while they were actively smoking a waterpipe.
What were the most important findings?
Smokers showed a significant shift in overall community composition (beta diversity, PERMANOVA p = 0.001), while richness measures (alpha diversity) did not differ. The phylum Firmicutes was elevated and Proteobacteria was depleted in smokers. LEfSe identified 16 differentially abundant taxa (log LDA score above 3.0). Facultative anaerobes tended to increase in smokers while aerobes declined. Thirty-seven microbial metabolic pathways differed between groups. Most were enriched in smokers, including pathways for polymer degradation, amino acid metabolism, polyamine synthesis, and peptidoglycan biosynthesis.
What are the greatest implications of this study?
The findings suggest waterpipe smoking disturbs the salivary microbial balance, shifting it toward a less oxygenated, dysbiotic state that may raise risk for oral and respiratory disease. The authors frame this as early evidence rather than proof of causation. Because the study is cross-sectional and saliva reflects the whole oral cavity, it cannot establish timing or site-specific effects on periodontal tissue. The small, young, male-only sample limits generalizability. Larger longitudinal and metagenomic studies are needed to confirm the taxonomic and metabolic shifts observed.