None listed
Conditions
Brief summary
There is evidence that oxidative stress contributes to the pathogenesis of hypertension. The primary objective of the study was to determine if vitamin C and polyphenols, alone or in combination, can lower blood pressure in hypertensive individuals.
Interventions
Following a 3-week run-in period (during which tea and coffee intake was limited to 3 cups per day and all red wine was ceased), subjects were allocated to a study treatment via block randomization using computer-generated random numbers, devised by the statistician. Volunteers were assigned to receive either (1) 500 mg/day vitamin C and matched grape-seed polyphenol placebo, (2) 1000 mg/day grape-seed polyphenols and matched vitamin C placebo, (3) 500 mg/day vitamin C and 1000 mg/day grape-seed
Following a 3-week run-in period (during which tea and coffee intake was limited to 3 cups per day and all red wine was ceased), subjects were allocated to a study treatment via block randomization using computer-generated random numbers, devised by the statistician. Volunteers were assigned to receive either (1) 500 mg/day vitamin C and matched grape-seed polyphenol placebo, (2) 1000 mg/day grape-seed polyphenols and matched vitamin C placebo, (3) 500 mg/day vitamin C and 1000 mg/day grape-seed polyphenols, or (4) matched placebo tablets for both grape-seed polyphenols and vitamin C. Participants took assigned tablets during a 6 week intervention period in a double-blind fashion. Tablets were taken twice daily at meal times as 250 mg and 500 mg of vitamin C and polyphenols, respectively. All tablets were identical in appearance, size. All study personnel and participants were blinded to treatment assignment for the duration of the study. Outcome measurements were performed at the end of the run-in period (baseline) and again at the end of the 6 week intervention period.
Sponsors
The University of Western Australia
Study design
Allocation
Randomised controlled trial
Intervention model
Factorial
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
21 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
All individuals were taking one or more antihypertensive drugs for 3 months, had a mean 24-h ambulatory systolic BP of 125 mmHg and at least one additional cardiovascular disease (CVD) risk factor. Risk factors included previous coronary or cerebrovascular event > 6 months, hyperlipidaemia (total cholesterol > 6 mmol/l), use of lipid-lowering therapy, or smoking > 5 cigarettes/day. All volunteers ceased any vitamin, fish oil or antioxidant supplements for at least 3 weeks prior to study entry. All usual medication was taken as prescribed on the morning of each visit and maintained for the duration of the trial.
Exclusion criteria
Exclusion criteria included: previous coronary or cerebrovascular event 6 months, heart failure or unstable disease, premenopausal, use of nitrate medication, use of oral contraceptive, body mass index > 35 kg/m2, diabetes mellitus, fasting glucose 7 mmol/l, or elevated serum creatinine (men > 110 mmol/l or women > 100 mmol/l). Individuals were asked to limit tea and coffee intake to 3 cups/day, and cease all red wine and commercial fruit juice for the duration of the study.
Outcome results
None listed