Smoking Alters Salivary Microbiota in Potential Path to Disease Risk


Salivary microbiota changes caused by cigarette smoking may affect metabolic pathways and increase disease risk.


  • The researchers analyzed health information and data on the composition of salivary microbiota from 1601 adult participants in the Cooperative Health Research in South Tyrol (CHRIS) microbiome study (CHRISMB); CHRIS is an ongoing study in Italy.

  • The average age of the study population was 45 years; 53% were female, and 45% were current or former smokers.

  • The researchers hypothesized that changes in salivary microbial composition would be associated with smoking, with more nitrate-reducing bacteria present, and that nitrate reduction pathways would be reduced in smokers.


  • The researchers identified 44 genera that differed in the salivary microbiota of current smokers and nonsmokers. In smokers, seven genera in the phylum Proteobacteria were decreased and six in the phylum Actinobacteria were increased compared with nonsmokers; these phyla contain primarily aerobic and anaerobic taxa, respectively.

  • Some microbiota changes were significantly associated with daily smoking intensity; genera from the classes Betaproteobacteria (Lautropia or Neisseria), Gammaproteobacteria (Cardiobacterium), and Flavobacteriia (Capnocytophaga) decreased significantly with increased grams of tobacco smoked per day, measured in 5-g increments.

  • Smoking was associated with changes in the salivary microbiota; the nitrate reduction pathway was significantly lower in smokers compared with nonsmokers, and these decreases were consistent with previous studies of decreased cardiovascular events in former smokers.

  • However, the salivary microbiota of smokers who had quit for at least 5 years resembled that of individuals who had never smoked.


“Decreased microbial nitrate reduction pathway abundance in smokers may provide an additional explanation for the effect of smoking on cardiovascular and periodontal diseases risk, a hypothesis which should be tested in future studies,” the researchers wrote.


The lead author of the study was Giacomo Antonello, MD, of Eurac Research, Affiliated Institute of the University of Lübeck, Bolzano, Italy. The study was published online in Scientific Reports (a Nature journal) on November 2, 2023.


The cross-sectional design and lack of professional assessment of tooth and gum health were limiting factors, as were potential confounding factors including medication use, diet, and alcohol intake.


The study was supported by the Department of Innovation, Research and University of the Autonomous Province of Bolzano-South Tyrol and by the European Regional Development Fund. The CHRISMB microbiota data generation was funded by the National Institute of Dental and Craniofacial Research. The researchers had no financial conflicts to disclose.

Source: Read Full Article