Acute ingestion of beetroot juice increases exhaled nitric oxide in healthy individuals

PLoS One. 2018 Jan 25;13(1):e0191030. doi: 10.1371/journal.pone.0191030. eCollection 2018.

Abstract

Background and objective: Nitric oxide (NO) plays an important role in the airways' innate immune response, and the fraction of exhaled NO at a flow rate of 50mL per second (FENO50) has been utilized to capture NO. Deficits in NO are linked to loss of bronchoprotective effects in airway challenges and predict symptoms of respiratory infection. While beetroot juice supplements have been proposed to enhance exercise performance by increasing dietary nitrate consumption, few studies have examined the impact of beetroot juice or nitrate supplementation on airway NO in contexts beyond an exercise challenge, which we know influences FENO50.

Methods: We therefore examined the influence of a beetroot juice supplement on FENO50 in healthy males and females (n = 38) during periods of rest and in normoxic conditions. FENO50, heart rate, blood pressure, and state affect were measured at baseline, 45 minutes, and 90 minutes following ingestion of 70ml beetroot juice (6.5 mmol nitrate). Identical procedures were followed with ingestion of 70ml of water on a control day.

Results: After beetroot consumption, average values of the natural log of FENO50 (lnFENO50) increased by 21.3% (Cohen's d = 1.54, p < .001) 45 minutes after consumption and by 20.3% (Cohen's d = 1.45, p < .001) 90 min after consumption. On the other hand, only very small increases in FENO50 were observed after consumption of the control liquid (less than 1% increase). A small subset (n = 4) of participants completed an extended protocol lasting over 3 hours, where elevated levels of FENO50 persisted. No significant changes in cardiovascular measures were observed with this small single dose of beetroot juice.

Conclusion: As NO serves a key role in innate immunity, future research is needed to explore the potential clinical utility of beetroot and dietary nitrate to elevate FENO50 and prevent respiratory infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Beta vulgaris / chemistry*
  • Breath Tests*
  • Cardiovascular System / drug effects
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nitric Oxide / analysis*
  • Plant Extracts / pharmacology*
  • Young Adult

Substances

  • Plant Extracts
  • Nitric Oxide

Grant support

This work was supported by the Southern Methodist University Research Council Grant (No. 401259). The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.