Role of ‘NO’ is very crucial in the physiological response and adaptation to hypoxia.
A reduced fraction of oxygen in inspired air leads to reduction in arterial oxygen concentration and intracellular partial pressure of oxygen. Increased metabolic imbalance and reduced functional capacity due to muscle hypoxia is quite common in higher altitude areas and in several disease conditions (Kenjale et al., 2011).
Nitric oxide plays a crucial part in restoring the oxygen supply via hypoxia-induced vasodilatation. Similarly, nitrite and nitrate may also promote hypoxic vasodilatation in an NO-independent manner (Dalsgaard et al., 2011).
Hence, dietary nitrate supplementation, such as beetroot extract represents a practically viable method of increasing plasma nitrate and nitrite concentration, which in turn helps improve vasodilation and oxygen supply.
In a double-blind, crossover study, 12 healthy subjects were given beetroot extract (140 ml/day) [either nitrate-rich (= 8.4 mmol of nitrate) or nitrate-depleted] for 3 days prior to moderate-intensity and severe-intensity exercise tests in hypoxic and normal conditions.
Nitrate-rich beetroot extract showed faster oxygen uptake kinetics during modern-intensity physical work or hypoxic condition when compared to nitrate-depleted beetroot extract. It was also observed that dietary nitrate demonstrated an improvement in tolerance to severe-intensity exercise under hypoxic condition, but not under normal conditions (Kelly et al., 2014).