The effects of chronic beetroot supplementation on nitrate reducing bacteria in the oral cavity

Mia Burleigh, Luke Liddle, Christopher Monaghan, David J. Muggeridge, Nicholas Sculthorpe, John Butcher, Fiona Henriquez, Chris Easton

Research output: Chapter in Book/Report/Conference proceedingConference contribution


IntroductionDietary nitrate (NO3-) supplementation can increase nitrite (NO2-) bioavailability following the reduction of NO3- to NO2- by NO3- reducing symbiotic bacteria in the oral cavity and, in some contexts, improve exercise performance. Whilst the factors that influence the abundance of these bacteria are unclear, data from animal models suggests these are enhanced through additional NO3- in the diet. The purpose of this study was to determine the effects of chronic NO3- supplementation on the oral microbiome of healthy humans. 
MethodsEleven healthy males (age 30 ± 7 year and body mass 86.9 ± 14.1 kg) consumed 2 x 70 ml shots of NO3- rich beetroot juice (one mid-morning and one mid-evening,~ 12.4 mmol/day-1) or NO3- depleted placebo for 7 days in a crossover design separated by a minimum of 4 weeks. Blood and saliva samples were collected at the beginning and end of each condition following 30 min of lying supine. Samples were analysed for [NO2-] and [NO3-] using gas-phase chemiluminescence. The posterior dorsal surface of the tongue was sampled for bacteria with 16s rRNA gene sequencing of the v3-v4 region. Quality filtered sequences were clustered de novo and binned into operational taxonomic units based on 97% identity using Qiime software. Taxonomy was assigned using the RDP classifier trained to the GreenGenes database (October 2013 release). 
ResultsNO3- supplementation significantly altered NO3- reducing bacteria; Neisseria subflava were increased (from 1.9% ± 2.2% to 8.0% ± 4.9%, P < 0.001), but Prevotella melaninogenica were decreased (from 24.9% ± 11.9% to 11.6% ± 7.5%, P = 0.001). Neisseria subflava were also significantly increased in the placebo condition but to lesser extent (from 1% ± 1.1% to 3.2% ± 2.9%, P = 0.008). There were no significant changes in any other NO3- reducing bacteria all (P > 0.05). Saliva and plasma [NO2-] and [NO3-] were significantly elevated after 7 days NO3- supplementation (all (P < 0.05) but not altered following placebo intervention (all P > 0.05). 
ConclusionsWe demonstrate that the oral microbiome can be altered through consumption of NO3- rich beetroot juice with increases in Neisseria subflava and decreases in Prevotella melaninogenica. These results are interesting given that an altered microbiome will alter NO3- reduction capacity and may consequently have effects on performance. In addition, given that Neisseria subflava are non-pathogenic and Prevotella melaninogenica are commonly associated with periodontitis and dental caries, these data further support the notion that NO3- supplementation may have benefits to health.
Original languageEnglish
Title of host publication23rd Annual Congress of the European College of Sport Science, 4th - 7th July 2018, Dublin - Ireland
Subtitle of host publicationBook of Abstracts
EditorsM. Murphy, C. Boreham, G. De Vito, E. Tsolakidis
Place of PublicationCologne
PublisherEuropean College of Sport Science
Number of pages1
ISBN (Print)978-3-9818414-1-1
Publication statusPublished - 2018
Event23rd Annual Congress of the European College of Sport Science: Sport Science at the Cutting Edge - University College Dublin and Ulster University, Dublin, Ireland
Duration: 4 Jul 20187 Jul 2018 (Conference website)


Conference23rd Annual Congress of the European College of Sport Science
Abbreviated titleECSS 2018
Internet address


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