Acute effects of resveratrol on circulatory function in obese people with elevated blood pressure.

INTERVENTION: Volunteers will be required to consume three doses of resveratrol (30, 90 or 270mg on one occasion per dose). There will be four separate visits (of one hour duration each) to the research centre which will occur with a one week washout between visits. At each visit the participant will consume one dose of resveratrol (or placebo) per visit. Measurements of endothelial vasodilator function and blood pressure responses to exercise will begin one hour after consumption of each single dose of resveratrol. These measures will be repeated at each visit. Resveratrol will be administered orally in capsules. Each of the three doses of resveratrol consists of multiple capsules; all capsules that make up a single dose will be consumed at once. Doses will be made up of combinations of 15 and 75 mg resveratrol capsules as follows: 1) 30 mg: 2 capsules of 15 mg + 4 placebo capsules 2) 90 mg: 1 capsule of 75 mg + 1 capsule of 15 mg + 4 placebo 3) 270 mg: 3 capsules of 75 mg + 3 of 15 mg CONDITION: Blood pressure response to exercise Endothelial vasodilator function PRIMARY OUTCOME: Degree of change in vasodilator function assessed by flow mediated dilatation in the brachial artery. SECONDARY OUTCOME: A small blood sample will be taken one hour after the consumption of each dose of resveratrol or placebo to assess plasma levels of resveratrol. ; Blood samples will be sent to DSM in Switzerland for analysis. Blood pressure responses to exercise will be assessed continuously using a Finapres blood pressure monitor, which measures blood pressure non‐invasively through the finger. INCLUSION CRITERIA: Men or post‐menopausal women (self reported cessation of menses for at least 12 months) aged 30 ‐ 70 years. b) Volunteers will be overweight or obese (Body mass index (BMI) ranging from 25kg/m2 to 35kg/m2), and c) have high‐normal BP or untreated mild primary hypertension (systolic BP 130‐160 mmHg or Diastolic BP 85‐100 mmHg) d) but are otherwise healthy. Volunteers will provide a blood sample on the first day of testing to assess blood chemistry, coagulation and hematology outcomes to ensure there are no underlying medical conditions that would influence the study outcomes.