Nitrate-rich vegetables increase plasma nitrate and nitrite concentrations and lower blood pressure in healthy adults

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/m2 ): 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.