The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults

Abstract Oral microbiome transplantation (OMT) has the potential to serve as a therapeutic approach for managing dental caries; however, it is essential to identify suitable donors. The aim of this study was to analyse the relationship between dietary (i.e., energy, water, carbohydrate and sugar int...

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Main Authors: Sonia Nath, Peter Zilm, Lisa Jamieson, Pedro Henrique Ribeiro Santiago, Don Hasan Kevin Ketagoda, Laura Weyrich
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-03455-0
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author Sonia Nath
Peter Zilm
Lisa Jamieson
Pedro Henrique Ribeiro Santiago
Don Hasan Kevin Ketagoda
Laura Weyrich
author_facet Sonia Nath
Peter Zilm
Lisa Jamieson
Pedro Henrique Ribeiro Santiago
Don Hasan Kevin Ketagoda
Laura Weyrich
author_sort Sonia Nath
collection DOAJ
description Abstract Oral microbiome transplantation (OMT) has the potential to serve as a therapeutic approach for managing dental caries; however, it is essential to identify suitable donors. The aim of this study was to analyse the relationship between dietary (i.e., energy, water, carbohydrate and sugar intake), saliva quality (i.e., saliva flow rate and salivary pH), and clinical factors (i.e., past caries experience and fluoride exposure) on the oral microbiome composition of potential OMT donors. For this cross-sectional study, a comprehensive dental examination was conducted for 93 healthy, caries-free adults (aged 18–85 years) without systemic or oral disease. All participants completed questionnaires on food frequency and socio-economic, lifestyle, and behavioural factors. Supragingival plaque samples were collected, and bacterial 16S rRNA genes were amplified, sequenced, and assigned to bacterial taxa. Stimulated saliva samples were collected for salivary flow rate and pH measurements. Constrained partial ordination analysis revealed that dietary factors, such as carbohydrate and sugar intake, had strong directional influences on microbial composition, while salivary factors like flow rate and pH showed opposing effects. Correlation analysis linked high sugar intake and reduced salivary pH to increased Streptococcus abundance. Differential abundance analysis identified significantly higher abundance of Streptococcus species among low water and high carbohydrate and sugar consumers. In mediation analysis, sugar consumption was directly and indirectly linked to reduced salivary pH, with Streptococcus showing a significant negative mediation effect (mean: -0.198; 95% CI: -0.387 to -0.010). High carbohydrate and sugar intake significantly influenced alpha diversity metrics (p < 0.05). Beta diversity permutational multivariate ANOVA revealed that covariates explained 11.45–12.52% of microbial variation (p < 0.05). This study emphasises that OMT donors with diverse oral microbiomes, low sugar and carbohydrate intake, and reduced levels of acidogenic taxa, such as Streptococcus, which significantly mediate salivary pH reduction, may be preferred for caries prevention.
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spelling doaj-art-34fb1acdd6894ffaa6ddddb62e070bcd2025-08-20T03:22:09ZengNature PortfolioScientific Reports2045-23222025-05-0115111010.1038/s41598-025-03455-0The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adultsSonia Nath0Peter Zilm1Lisa Jamieson2Pedro Henrique Ribeiro Santiago3Don Hasan Kevin Ketagoda4Laura Weyrich5Australian Research Centre of Population Oral Health, Adelaide Dental School, The University of AdelaideAustralian Research Centre of Population Oral Health, Adelaide Dental School, The University of AdelaideAustralian Research Centre of Population Oral Health, Adelaide Dental School, The University of AdelaideAustralian Research Centre of Population Oral Health, Adelaide Dental School, The University of AdelaideAustralian Research Centre of Population Oral Health, Adelaide Dental School, The University of AdelaideSchool of Biological Sciences, University of AdelaideAbstract Oral microbiome transplantation (OMT) has the potential to serve as a therapeutic approach for managing dental caries; however, it is essential to identify suitable donors. The aim of this study was to analyse the relationship between dietary (i.e., energy, water, carbohydrate and sugar intake), saliva quality (i.e., saliva flow rate and salivary pH), and clinical factors (i.e., past caries experience and fluoride exposure) on the oral microbiome composition of potential OMT donors. For this cross-sectional study, a comprehensive dental examination was conducted for 93 healthy, caries-free adults (aged 18–85 years) without systemic or oral disease. All participants completed questionnaires on food frequency and socio-economic, lifestyle, and behavioural factors. Supragingival plaque samples were collected, and bacterial 16S rRNA genes were amplified, sequenced, and assigned to bacterial taxa. Stimulated saliva samples were collected for salivary flow rate and pH measurements. Constrained partial ordination analysis revealed that dietary factors, such as carbohydrate and sugar intake, had strong directional influences on microbial composition, while salivary factors like flow rate and pH showed opposing effects. Correlation analysis linked high sugar intake and reduced salivary pH to increased Streptococcus abundance. Differential abundance analysis identified significantly higher abundance of Streptococcus species among low water and high carbohydrate and sugar consumers. In mediation analysis, sugar consumption was directly and indirectly linked to reduced salivary pH, with Streptococcus showing a significant negative mediation effect (mean: -0.198; 95% CI: -0.387 to -0.010). High carbohydrate and sugar intake significantly influenced alpha diversity metrics (p < 0.05). Beta diversity permutational multivariate ANOVA revealed that covariates explained 11.45–12.52% of microbial variation (p < 0.05). This study emphasises that OMT donors with diverse oral microbiomes, low sugar and carbohydrate intake, and reduced levels of acidogenic taxa, such as Streptococcus, which significantly mediate salivary pH reduction, may be preferred for caries prevention.https://doi.org/10.1038/s41598-025-03455-0Dental cariesMediation analysisMicrobiotaOral health16S ribosomal RNASequencing
spellingShingle Sonia Nath
Peter Zilm
Lisa Jamieson
Pedro Henrique Ribeiro Santiago
Don Hasan Kevin Ketagoda
Laura Weyrich
The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
Scientific Reports
Dental caries
Mediation analysis
Microbiota
Oral health
16S ribosomal RNA
Sequencing
title The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
title_full The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
title_fullStr The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
title_full_unstemmed The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
title_short The influence of diet, saliva, and dental history on the oral microbiome in healthy, caries-free Australian adults
title_sort influence of diet saliva and dental history on the oral microbiome in healthy caries free australian adults
topic Dental caries
Mediation analysis
Microbiota
Oral health
16S ribosomal RNA
Sequencing
url https://doi.org/10.1038/s41598-025-03455-0
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