Study of Oral Microbiome Describes the Mouth of America
, by Brittany Cordeiro, B.A.
A microscopic image of bacteria on a blue background.
In a new study, NCI researchers characterized the oral microbiome of US adults to create comprehensive data and provide a deeper understanding of its role in human health. The findings published in JAMA Network Open on May 5, 2025.
The cross-sectional study, led by Christian Abnet, Ph.D., director and senior investigator in the Metabolic Epidemiology Branch, analyzed oral samples from 8,237 adults aged 18 to 69 years in the National Health and Nutrition Examination Survey (NHANES) collected between 2009 to 2012. NHANES included demographics, diet, tobacco use, and medical history as well as health, dental, anthropometric and biomedical examinations and biospecimen collection.
Their findings show that nearly all US adults (>99%) have five phyla and six bacterial genera in their mouths. The genera (Veillonella, Steptococcus, Prevotella 7, Rothia, Actinomyces, and Gemella) indicate a limited universal oral microbiome in our populaiton. A different set of genera (Aggregatibacter, Lactococcus, and Haemophilus) were associated with a higher proportion of variability in oral microbiome beta diversity, showing there are key genera that potentially affect oral microbiome diversity across individuals. Factors like age, race and ethnicity, smoking, body mass index (BMI), alcohol use, and periodontal disease were associated with the oral microbiome (alpha diversity, beta diversity, and genus-level prevalence and relative abundance). Observations included enrichment of Actinobacteria among current smokers and red complex bacteria in individuals with severe periodontal disease.
In addition, they observed an unexpected pattern for the number of types of bacteria present, with complexity increasing until age 30 and then declining thereafter. This measure of community complexity was significantly lower among non-Hispanic Whites, and increased with greater BMI, alcohol use, and periodontal disease severity.
This study was supported by a grant from the FDA Center for Tobacco Products and NCI Intramural Research Program and provides a contemporary reference standard for the oral bacterial microbiome, a complex ecosystem encompassing 37 phyla and over 1000 genera. Alterations in the oral microbiome have been associated with several chronic diseases, including cancer, diabetes, cardiovascular disease, and neurological disorders. The key findings of the study can be a starting point for future studies to identify potential biological mechanisms linking oral microbes to health outcomes.
REFERENCE
Abnet CC, et. al. Oral Microbiome Profile of the US Population. JAMA Network Open. 2025.