Oral Temperature and pH Influence Dietary Nitrate Metabolism in Healthy Adults

Stuart P Cocksedge, Adam J Causer, Paul G Winyard, Andrew M Jones, Stephen J Bailey

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This study tested the hypothesis that the increases in salivary and plasma [NO 2 ] after dietary NO 3 supplementation would be greater when oral temperature and pH were independently elevated, and increased further when oral temperature and pH were elevated concurrently. Seven healthy males (mean ± SD, age 23 ± 4 years) ingested 70 mL of beetroot juice concentrate (BR, which provided ~6.2 mmol NO 3 ) during six separate laboratory visits. In a randomised crossover experimental design, salivary and plasma [NO 3 ] and [NO 2 ] were assessed at a neutral oral pH with a low (T Lo-pH Norm), intermediate (T Mid-pH Norm), and high (T Hi-pH Norm) oral temperature, and when the oral pH was increased at a low (T Lo-pH Hi), intermediate (T Mid-pH Hi), and high (T Hi-pH Hi) oral temperature. Compared with the T Mid-pH Norm condition (976 ± 388 µM), the mean salivary [NO 2 ] 1–3 h post BR ingestion was higher in the T Mid-pH Hi (1855 ± 423 µM), T Hi-pH Norm (1371 ± 653 µM), T Hi-pH Hi (1792 ± 741 µM), T Lo-pH Norm (1495 ± 502 µM), and T Lo-pH Hi (2013 ± 662 µM) conditions, with salivary [NO 2 ] also higher at a given oral temperature when the oral pH was increased (p < 0.05). Plasma [NO 2 ] was higher 3 h post BR ingestion in the T Mid-pH Hi, T Hi-pH Hi, and T Lo-pH Hi conditions, but not the T Lo-pH Norm and T Hi-pH Norm conditions, compared with T Mid-pH Norm (p < 0.05). Therefore, despite ingesting the same NO 3 dose, the increases in salivary [NO 2 ] varied depending on the temperature and pH of the oral cavity, while the plasma [NO 2 ] increased independently of oral temperature, but to a greater extent at a higher oral pH.

Original languageEnglish
Article number784
Issue number3
Publication statusPublished - 3 Feb 2023

Bibliographical note

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© 2023 by the authors.

Copyright 2023 Elsevier B.V., All rights reserved.


  • Humans
  • Adult
  • Male
  • Young Adult
  • Nitrates
  • Nitrites
  • Nitrogen Dioxide/metabolism
  • Temperature
  • Saliva/metabolism
  • Beta vulgaris
  • Hydrogen-Ion Concentration
  • Dietary Supplements

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