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/m(2)): 23 +/- 1; exercise: 1-10 h/wk] ingested 4 different beverages, each containing 800 mg (similar to 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 mu mol/L; beetroot juice: 597 +/- 23 mu mol/L; rocket salad beverage: 584 +/- 24 mu mol/L; spinach beverage: 584 +/- 23 mu mol/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.