Analysis of the Impact of Dietary Nitrate Intake on Vascular Function in Physically Active Adults (P06-101-19)

Abstract

ObjectivesDietary nitrate, provided by certain vegetables, may serve as a potential source of the potent vasodilator nitric oxide (NO). This may be of importance in situations of reduced blood flow or increased tissue oxygen demand, such as during tissue ischemia or exercise. This study tested the effects of a nitrate-rich vegetable juice, providing ∼200 mg of nitrate or an isocaloric control beverage on blood pressure, microvascular function and plasma total nitrate/nitrite and nitrite and nitroso species (RXNO). MethodsFifteen healthy and active adult males (32.7 ± 7.2 years of age) were enrolled into a randomized double-blind, controlled crossover trial. Each participant consumed the test beverages after an overnight fast. Vascular measures and blood samples were collected at baseline (0 h), and at 1 h, 2 h, and 4 h post beverage intake. ResultsNo significant changes in blood pressure were observed. Total nitrate/nitrite levels significantly increased compared to baseline and control for all post intake time points, with peak levels occurring 1–2 h post intake. Similar effects were observed with RXNO, with peak RXNO levels occurring 1 h post intake. Significant increases in microvascular function, the Framingham RHI (fRHI), were observed 1 h, 2 h and 4 h post beverage intake, but treatment effects were not significant. However, fRHI at 0 h and 2 h was significantly and positively correlated with Nitrate/nitrite and RXNO (ρ = 0.343, p = 0.02 and ρ = 0.486, 0.009, respectively) and with nitrate/nitrite only at 0 h and 1 h (ρ = 0.343, p = 0.020). At the 1 h and 2 h time points, using ANCOVA with baseline adjustment, a significant increase in fRHI was observed 2 h after nitrate-rich vegetable juice intake compared to control. ConclusionsIn conclusion, circulating nitrate/nitrite and RXNO levels were associated with improved fRHI response 2 h after the intake of a nitrate-rich vegetable juice. It is important to note that the levels of nitrate provided were considered at a low level of intake (∼200 mg) compared to previous reports of reduced blood pressure after the intake of high levels of nitrate (∼1 g). These results suggest that the nitrate containing beverage has the potential to improve microvascular function. Funding SourcesThe beverages and research funding were provided from the Campbell Soup Company.