Nitrate ingestion blunts the increase in blood pressure during cool air exposure. A double-blind, placebo-controlled, randomized, crossover trial

Samantha N. Rowland, Emma O'Donnell, Lewis J. James, Mariasole Da Boit, Naoto Fujii, Josh T. Arnold, Alex B. Lloyd, Clare M. Eglin, Anthony I. Shepherd, Stephen J. Bailey

Research output: Contribution to journalArticlepeer-review

Abstract

Cold exposure increases blood pressure (BP) and salivary flow rate (SFR). Increased cold-induced SFR would be hypothesised to enhance oral nitrate delivery for reduction to nitrite by oral anaerobes and to subsequently elevate plasma [nitrite] and nitric oxide bioavailability. We tested the hypothesis that dietary nitrate supplementation would increase plasma [nitrite] and lower BP to a greater extent in cool compared to normothermic conditions. Twelve males attended the laboratory on four occasions. Baseline measurements were completed at 28°C. Subsequently, participants ingested 140 mL of concentrated nitrate-rich (BR; ~13 mmol nitrate) or nitrate-depleted (PL) beetroot juice. Measurements were repeated over 3 h at either 28°C (Norm) or 20°C (Cool). Mean skin temperature was lowered compared to baseline in PL-Cool and BR-Cool. SFR was greater in BR-Norm, PL-Cool and BR-Cool than PL-Norm. Plasma [nitrite] at 3 h was higher in BR-Cool (592 ± 239 nM) vs. BR-Norm (410 ± 195 nM). Systolic BP (SBP) at 3 h was not different between PL-Norm (117 ± 6 mmHg) and BR-Norm (113 ± 9 mmHg). SBP increased above baseline at 1, 2 and 3 h in PL-Cool but not BR-Cool. These results suggest that BR consumption is more effective at increasing plasma [nitrite] in cool compared to normothermic conditions and blunts the rise in BP following acute cool air exposure, which might have implications for attenuating the increased cardiovascular strain in the cold.
Original languageEnglish
Pages (from-to)1364-1375
Number of pages12
JournalJournal of Applied Physiology
Volume136
Issue number6
Early online date4 Apr 2024
DOIs
Publication statusPublished - Jun 2024

Keywords

  • beetroot
  • cardiovascular strain
  • inorganic nitrate
  • nitric oxide
  • thermoregulation

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