Reduced nitric oxide (NO) availability is a hallmark of a number of cardiovascular diseases (CVD) including peripheral artery disease (PAD). The investigators will test the hypothesis that sub-chronic NEO40™ supplementation will improve vascular NO function and improve intermittent claudication in patients with PAD. Using a prospective, double blind, placebo controlled experimental design in 30 patients, graded treadmill tests will be performed at baseline and after 3 months after randomization, according to the Skinner-Gardner protocol. Initial claudication distance (ICD) and absolute claudication distance (ACD) will be recorded. Two consecutive treadmill tests will be performed within 1 week at baseline (before administration of study drug); and 2 test will be performed at 3 months. Functional status will also be assessed by the Walking Impairment Questionnaire and the Health Status Survey SF-36 questionnaire (SF-36). Vascular function will be assessed with the use of a Vendys® vascular reactivity (endothelial function) test (Endothelix Inc). Digital pulse amplitude will be assessed using sensor probes on the index finger during reactive hyperemia. Blood will be collected for measurement (by Neogenis) of plasma levels of nitrite and nitrate at baseline and at the completion of the study. Based on previously published trials using this NO technology, the investigators predict that the group receiving the active supplement will exhibit an improvement in claudication distance and all measures of vascular function after 3 months.