Salivary nitrate--an ecological factor in reducing oral acidity
Open accessAbstract
Human oral cavities represent a novel environment with a constant supply of concentrated nitrate. For humans, over 80% of dietary nitrate originates from fruit and vegetables. With a healthy, balanced diet, rich in fruit and vegetables, the concentration of nitrate in saliva can reach up to more than three times the European drinking water standard. The physiological function of the active excretion of salivary nitrate is unknown. Furthermore, little is known of the ecological function of oral nitrate and the effect on the oral environment during its subsequent oral microbial conversions. The objectives of the research were to investigate the effect on salivary pH coupled with oral microbial nitrate and/or nitrite reduction. Human saliva samples were incubated anaerobically in the presence of 111.0 mmol glucose (2%), with and without 1.5 mmol nitrate/nitrite, and pH and nitrate/nitrite consumption were measured during the time-course of the incubations. We found that anaerobic incubation of saliva containing a mixture of oral bacteria in the presence of nitrate/nitrite substrates and glucose resulted in a higher pH than was found in controls in the absence of nitrate/nitrite. These results suggest that the presence of these electron acceptors repressed acid fermentation, or increased alkali production, or consumed acid produced, thus reducing salivary acidity. This finding identifies salivary nitrate as a possible ecological factor in reducing oral acidity. The possibility that a symbiotic relationship between host nitrate excretion and nitrate-reducing microorganisms might help to protect against tooth decay should be explored further.
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This may relate to the paradoxical association between nitrate-reducing oral bacteria and protection from dental caries.
“This may relate to the paradoxical association between nitrate-reducing oral bacteria and protection from dental caries[191,205,232,238,239].”
From Enterosalivary nitrate metabolism and the microbiome: Intersection of microbial metabolism, nitric oxide and diet in cardiac and pulmonary vascular health (2017) · cites this paper as [239]
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- Authors
- Li, H., Thompson, I., Carter, P., Whiteley, A., Bailey, M., Leifert, C., & Killham, K.
- Affiliations
- University of Oxford (GB)
- Newcastle University (GB)
- University of Aberdeen (GB)
- Corresponding author
- Li, H.
- Venue
- Oral Microbiology and Immunology
- Publisher
- Wiley
- Published
- 2007-01-12
- Volume
- 22
- Issue
- 1
- Pages
- 67-71
- ISSN
- 0902-0055 (ISSN-L)
- 1399-302X
- OpenAlex
- W2084711325
- Cited by
- 45
- References
- 35
- Citations by year
- 2026: 1 · 2025: 4 · 2024: 5 · 2023: 3 · 2022: 3 · 2021: 5 · 2020: 6 · 2019: 1 · 2017: 2 · 2016: 4 · 2015: 1 · 2014: 1 · 2013: 3
- FWCI
- 1.88
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Oral Microbiology and Immunology (publishedVersion)
- PubMed (publishedVersion)
- NERC Open Research Archive (Natural Environment Research Council) (acceptedVersion)
- UWA Profiles and Research Repository (UWA) (submittedVersion)
- Lancaster EPrints (Lancaster University) (submittedVersion)
- Newcastle University ePrints (Newcastle Univesity)
- Funders
- Eli Lilly and Company
- Natural Environment Research Council (CEH010023)
- Centre for Ecology and Hydrology
- Topics
- Health Sciences › Dentistry › Periodontics › Oral microbiology and periodontitis research
- Health Sciences › Dentistry › Periodontics › Dental Health and Care Utilization
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gut microbiota and health
- Keywords
- salivary nitrate, oral acidity, salivary pH, nitrate reduction, nitrite reduction, oral bacteria, anaerobic incubation, glucose fermentation, host-microbe symbiosis, dental caries prevention, dietary nitrate
- MeSH terms
- Acids, Adult, Aerobiosis, Alkalies, Bacteria, Ecology, Female, Fermentation, Glucose, Humans, Hydrogen-Ion Concentration, Male, Middle Aged, Mouth, Nitrates, Nitrites, Saliva, Oxidants
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