Investigation of the Effect of Dietary Nitrate Treatment on Endothelial Function and Platelet Reactivity in Hypercholesterolemics.

Diets rich in fruit and vegetables reduce the risk of strokes and heart attacks, however the exact cause of this beneficial effect is uncertain. Evidence suggests that certain vegetables, including beetroot and the green leafy vegetables, possess high inorganic nitrate concentrations. The investigators recent evidence suggests that inorganic nitrate provides a source of gas called nitric oxide in the body that exerts a number of beneficial effects upon the heart and blood vessels . The investigators have previously shown that beetroot juice ingestion improves blood vessel (vascular endothelial) and platelet function in healthy volunteers. Studies by the investigators show that these effects are due to conversion of nitrate to nitrite by symbiotic (helpful) bacteria (located on the tongue) and subsequent conversion of nitrite to nitric oxide in blood vessels. The investigators now wish to explore whether dietary nitrate, via its beneficial effects on platelets and blood vessels, might improve indices of atherosclerotic disease progression in high risk individuals (hypercholesterolemics). Recruits will have high cholesterol and no known atherosclerosis and will not yet be on any anti-cholesterol medications. Volunteers will consume a daily dose of beetroot juice or placebo nitrate-free juice for six weeks. Vascular function will be assessed using non-invasive techniques at the beginning and at the end of the study using ultrasound measurement of flow mediated dilatation (FMD) of the brachial artery in the arm and pulse wave analysis (PWA) and pulse wave velocity (PWV) to measure arterial compliance. To assess impact on platelet function, blood samples will also be taken at the start and at the end of the study.