Dietary Nitrate Supplementation and Thermoregulation

This is a double-blinded, randomized, crossover design study to assess the effects of dietary nitrate supplementation (beetroot juice) on peripheral artery disease (PAD) patients (ages 50-85) diagnosed with Fontaine stage I or II PAD (as determined by vascular surgeon at UNMC). Exclusion criteria include: 1) experience severe claudication (leg pain) at rest or tissue loss due to PAD (Fontaine stage III and IV), 2) have limited walking capacity due to conditions other than PAD, 3) are already supplementing with a form of dietary nitrate, or 4) have an allergy to beetroot juice. Subjects will be required to visit the lab 3 times and will be randomized to receive either the supplement or the placebo for the 2nd and 3rd visits. There will be a washout period of 14 days between the 2nd and 3rd visits. Visit 1 will take approximately 2 hours and the 2nd/3rd visits will take approximately 1.5 hours. Total experimentation period will last approximately 15 days. Visit 1 will consist of non-invasive baseline testing including assessment of endothelial function (flow-mediated dilation by ultrasound imaging), maximal walking capacity (Gardner treadmill protocol), leg function (near-infrared spectroscopy, time to onset claudication, blood flow to lower extremities), and body core temperature (rectal thermometer). Visits 2 and 3 will require consumption of either the supplement or placebo. The same tests from the baseline measurements will be performed for visits 2 and 3. There will be a recommended fourth visit, albeit not required, to review study results.