Topical Area: Dietary Bioactive Components
Dietary 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 ~200mg of nitrate or an isocaloric control beverage on blood pressure, microvascular function and plasma total nitrate/nitrite and nitrite and nitroso species (RXNO).
Fifteen 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 (0h), and at 1h, 2h, and 4h post beverage intake.
No 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 1-2h post intake. Similar effects were observed with RXNO, with peak RXNO levels occurring 1h post intake. Significant increases in microvascular function, the Framingham RHI (fRHI), were observed 1h, 2h and 4h post beverage intake, but treatment effects were not significant. However, fRHI at 0h and 2h 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 0h and 1h (ρ= 0.343, p=0.020). At the 1h and 2h time points, using ANCOVA with baseline adjustment, a significant increase in fRHI was observed 2h after nitrate-rich vegetable juice intake compared to control.
In conclusion, circulating nitrate/nitrite and RXNO levels were associated with improved fRHI response 2h 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 (~200mg) compared to previous reports of reduced blood pressure after the intake of high levels of nitrate (~1g). These results suggest that the nitrate containing beverage has the potential to improve microvascular function.
Funding Sources :
The beverages and research funding were provided from the Campbell Soup Company