Nitrate-Rich Vegetables Increase Plasma Nitrate and Nitrite Concentrations and Lower Blood Pressure in Healthy Adults

J Nutr. 2016 May;146(5):986-93. doi: 10.3945/jn.116.229807. Epub 2016 Apr 13.

Abstract

Background: Dietary nitrate is receiving increased attention due to its reported ergogenic and cardioprotective properties. The extent to which ingestion of various nitrate-rich vegetables increases postprandial plasma nitrate and nitrite concentrations and lowers blood pressure is currently unknown.

Objective: We aimed to assess the impact of ingesting different nitrate-rich vegetables on subsequent plasma nitrate and nitrite concentrations and resting blood pressure in healthy normotensive individuals.

Methods: With the use of a semirandomized crossover design, 11 men and 7 women [mean ± SEM age: 28 ± 1 y; mean ± SEM body mass index (BMI, in kg/m(2)): 23 ± 1; exercise: 1-10 h/wk] ingested 4 different beverages, each containing 800 mg (∼12.9 mmol) nitrate: sodium nitrate (NaNO3), concentrated beetroot juice, a rocket salad beverage, and a spinach beverage. Plasma nitrate and nitrite concentrations and blood pressure were determined before and up to 300 min after beverage ingestion. Data were analyzed using repeated-measures ANOVA.

Results: Plasma nitrate and nitrite concentrations increased after ingestion of all 4 beverages (P < 0.001). Peak plasma nitrate concentrations were similar for all treatments (all values presented as means ± SEMs: NaNO3: 583 ± 29 μmol/L; beetroot juice: 597 ± 23 μmol/L; rocket salad beverage: 584 ± 24 μmol/L; spinach beverage: 584 ± 23 μmol/L). Peak plasma nitrite concentrations were different between treatments (NaNO3: 580 ± 58 nmol/L; beetroot juice: 557 ± 57 nmol/L; rocket salad beverage: 643 ± 63 nmol/L; spinach beverage: 980 ± 160 nmol/L; P = 0.016). When compared with baseline, systolic blood pressure declined 150 min after ingestion of beetroot juice (from 118 ± 2 to 113 ± 2 mm Hg; P < 0.001) and rocket salad beverage (from 122 ± 3 to 116 ± 2 mm Hg; P = 0.007) and 300 min after ingestion of spinach beverage (from 118 ± 2 to 111 ± 3 mm Hg; P < 0.001), but did not change with NaNO3 Diastolic blood pressure declined 150 min after ingestion of all beverages (P < 0.05) and remained lower at 300 min after ingestion of rocket salad (P = 0.045) and spinach (P = 0.001) beverages.

Conclusions: Ingestion of nitrate-rich beetroot juice, rocket salad beverage, and spinach beverage effectively increases plasma nitrate and nitrite concentrations and lowers blood pressure to a greater extent than sodium nitrate. These findings show that nitrate-rich vegetables can be used as dietary nitrate supplements. This trial was registered at clinicaltrials.gov as NCT02271633.

Keywords: beetroot; bioavailability; blood pressure; nitrate; nitrite; rocket salad; spinach.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Beta vulgaris / chemistry*
  • Blood Pressure / drug effects*
  • Brassicaceae / chemistry*
  • Diet*
  • Female
  • Fruit and Vegetable Juices
  • Humans
  • Male
  • Nitrates / blood*
  • Nitrates / pharmacology
  • Nitrites / blood*
  • Plant Extracts / pharmacology
  • Reference Values
  • Spinacia oleracea / chemistry*
  • Vegetables / chemistry

Substances

  • Nitrates
  • Nitrites
  • Plant Extracts
  • sodium nitrate

Associated data

  • ClinicalTrials.gov/NCT02271633