Dietary Nitrate Intake Improves Vascular Function And Walking Capacity In Patients With Peripheral Artery Disease

Peripheral artery disease (PAD) is the manifestation of atherosclerosis in the arteries of the legs, which reduces blood flow to the lower extremities and impairs walking capacity. Dietary nitrate has been used to reduce blood pressure (BP) and increase exercise tolerance in PAD. However, a standard dose, body mass normalized nitrate, for PAD has yet to be determined. PURPOSE: To elucidate the impacts of a body mass-normalized dose of nitrate (0.11 mmol nitrate/kg) in the form of beetroot juice on resting heart rate (RHR), central and peripheral BP, vascular function, and exercise tolerance in patients with PAD. METHODS: In a randomized crossover design, 10 patients with PAD (stage II-III) received either the nitrate supplement or placebo. At each visit, measures of RHR, central and peripheral BP, brachial and popliteal artery endothelial function (flow-mediated dilation, FMD), arterial stiffness (pulse-wave velocity, PWV), augmentation index (AIx)), maximal walking capacity, and time to claudication (COT) were measured before and after nitrate and placebo. RESULTS: There were significant group by time interactions (p<0.05) for systolic BP, endothelial function, and maximal walking distance. Systolic BP was significantly reduced (p<0.05) while popliteal FMD, brachial FMD, and maximal walking time significantly increased (p<0.05). Nitrate intake reduced central systolic BP and increased maximal walking time (p<0.05). There were trends for decreased diastolic BP (p=0.15), central diastolic BP (p=0.06), and central pulse pressure (p=0.17). There were no changes in RHR, deceleration time, max dP/dt, carotid-to-radial PWV, carotid-to-femoral PWV, carotid-to-ankle PWV, AIx, or COT (p>0.05). CONCLUSIONS: These results indicate that a dose of nitrate (~0.11 mmol nitrate/kg) seems to be an effective dose for improving BP, vascular function, and walking capacity in patients with PAD.