Dietary nitrate supplementation enhances exercise performance in peripheral arterial disease

Area of Science:

• Cardiovascular Physiology
• Sports Science
• Nutritional Biochemistry

Background:

• Peripheral arterial disease (PAD) impairs blood and oxygen supply, causing claudication pain.
• Nitric oxide (NO) bioavailability is crucial for vascular health.
• Plasma nitrite (NO(2)(-)) may serve as a circulating source of NO, especially during hypoxia.

Purpose of the Study:

• To investigate if beetroot (BR) juice supplementation increases plasma nitrite levels.
• To determine if BR juice enhances exercise tolerance in PAD patients.
• To assess the impact of BR juice on gastrocnemius oxygenation during exercise.

Main Methods:

• Randomized, open-label, crossover study with 8 PAD subjects.
• Subjects consumed 500 ml beetroot juice (BR) or placebo (PL).
• Maximal cardiopulmonary exercise tests (CPX) were performed, with blood draws and near-infrared spectroscopy for muscle oxygenation.

Main Results:

• Beetroot juice significantly increased plasma nitrite concentrations compared to placebo.
• Subjects taking BR juice walked 18% longer before claudication pain and had 17% longer peak walking times.
• Gastrocnemius fractional oxygen extraction was reduced with BR juice, indicating improved oxygenation.

Conclusions:

• Dietary inorganic nitrate supplementation via beetroot juice enhances plasma nitrite levels.
• Beetroot juice improves exercise capacity and peripheral tissue oxygenation in PAD patients.
• NO(2)(-)-related NO signaling may be a therapeutic strategy for improving vascular function in PAD.