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Cited by 59Nitric Oxide and Endothelin EffectsOral microbiology and periodontitis researchExercise and Physiological Responses

Variability in nitrate-reducing oral bacteria and nitric oxide metabolites in biological fluids following dietary nitrate administration: an assessment of the critical difference

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Liddle, Luke, Burleigh, Mia C., Monaghan, Chris, Muggeridge, David J., Sculthorpe, Nicholas, Pedlar, Charles R., Butcher, John, Henriquez, Fiona L. +1 more·2019·Nitric Oxide
DOI 10.1016/j.niox.2018.12.003
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Abstract

There is conflicting evidence on whether dietary nitrate supplementation can improve exercise performance. This may arise from the complex nature of nitric oxide (NO) metabolism which causes substantial inter-individual variability, within-person biological variation (CVB), and analytical imprecision (CVA) in experimental endpoints. However, no study has quantified the CVA and CVB of NO metabolites or the factors that influence their production. These data are important to calculate the critical difference (CD), defined as the smallest difference between sequential measurements required to signify a true change. The main aim of the study was to evaluate the CVB, CVA, and CD for markers of NO availability (nitrate and nitrite) in plasma and saliva before and after the ingestion of nitrate-rich beetroot juice (BR). We also assessed the CVB of nitrate-reducing bacteria from the dorsal surface of the tongue. It was hypothesised that there would be substantial CVB in markers of NO availability and the abundance of nitrate-reducing bacteria. Ten healthy male participants (age 25 ± 5 years) completed three identical trials at least 6 days apart. Blood and saliva were collected before and after (2, 2.5 and 3 h) ingestion of 140 ml of BR (∼12.4 mmol nitrate) and analysed for [nitrate] and [nitrite]. The tongue was scraped and the abundance of nitrate-reducing bacterial species were analysed using 16S rRNA next generation sequencing. There was substantial CVB for baseline concentrations of plasma (nitrate 11.9%, nitrite 9.0%) and salivary (nitrate 15.3%, nitrite 32.5%) NO markers. Following BR ingestion, the CVB for nitrate (plasma 3.8%, saliva 12.0%) and salivary nitrite (24.5%) were lower than baseline, but higher for plasma nitrite (18.6%). The CD thresholds that need to be exceeded to ensure a meaningful change from baseline are 25, 19, 37, and 87% for plasma nitrate, plasma nitrite, salivary nitrate, and salivary nitrite, respectively. The CVB for selected nitrate-reducing bacteria detected were: Prevotella melaninogenica (37%), Veillonella dispar (35%), Haemophilus parainfluenzae (79%), Neisseria subflava (70%), Veillonella parvula (43%), Rothia mucilaginosa (60%), and Rothia dentocariosa (132%). There is profound CVB in the abundance of nitrate-reducing bacteria on the tongue and the concentration of NO markers in human saliva and plasma. Where these parameters are of interest following experimental intervention, the CD values presented in this study will allow researchers to interpret the meaningfulness of the magnitude of the change from baseline.

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Authors
Liddle, L., Burleigh, M. C., Monaghan, C., Muggeridge, D. J., Sculthorpe, N., Pedlar, C. R., Butcher, J., Henriquez, F. L., & Easton, C.
Affiliations
  • University of the West of Scotland (GB)
  • University of the Highlands and Islands (GB)
  • St Mary's University Twickenham London (GB)
  • Glasgow Caledonian University (GB)
Corresponding author
Easton, Chris
ORCID
Venue
Nitric Oxide
Publisher
Elsevier BV
Published
2019-02
Volume
83
Pages
1-10
ISSN
1089-8603 (ISSN-L)
DOI
10.1016/j.niox.2018.12.003
OpenAlex
W2902374800
Semantic Scholar
88afeda74216881ee424e0231db865b72634c3f0
Cited by
59
References
61
Citations by year
2026: 5 · 2025: 9 · 2024: 10 · 2023: 6 · 2022: 10 · 2021: 5 · 2020: 10 · 2019: 4
FWCI
3.26
Type
journal article
Language
en
Open access
Licence
Locations
  • Nitric Oxide (publishedVersion)
  • PubMed (publishedVersion)
  • The UWS Academic Portal (University of the West of Scotland) (publishedVersion, cc-by-nc-nd)
  • St Mary's University Repository (St Mary's University Twickenham London) (acceptedVersion)
  • ResearchOnline (acceptedVersion, cc-by-nc-nd)
  • Research Output (Edinburgh Napier University) (acceptedVersion, other-oa)
  • ResearchOnline (Glasgow Caledonian University) (acceptedVersion, cc-by-nc-nd)
  • BGRO - Business, Governance and Religious Organisations Repository (submittedVersion)
  • Edinburgh Napier Research Repository (Edinburgh Napier University) (submittedVersion, cc-by-nc-nd)
Funders
  • University of the West of Scotland
  • European Union’s INTERREG VA Programme
  • EU Programmes Body (SEUPB)
Topics
  • Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
  • Health Sciences › Dentistry › Periodontics › Oral microbiology and periodontitis research
  • Health Sciences › Medicine › Rehabilitation › Exercise and Physiological Responses
Keywords
dietary nitrate, beetroot juice, nitric oxide metabolism, nitrate-reducing bacteria, nitrite, nitrate, critical difference, analytical imprecision, saliva, plasma, tongue microbiota, exercise performance, interindividual variability, 16S rRNA gene sequencing, Prevotella melaninogenica, Veillonella dispar, Haemophilus parainfluenzae
MeSH terms
Fruit and Vegetable Juices, Administration, Oral, Adult, Anti-Bacterial Agents, Prevotella melaninogenica, Humans, Male, Microbial Sensitivity Tests, Micrococcaceae, Neisseria, Nitrates, Nitric Oxide, Veillonella, Biomarkers, Haemophilus parainfluenzae, Healthy Volunteers

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