Blood Pressure
Conditions
Keywords
Cardiovascular disease, endothelial function, nitrate, Vitamin C
Brief summary
The investigators have shown in two short-term studies in healthy, young participants that the combined supplementation of inorganic nitrate with vitamin C has beneficial effects on blood pressure and blood vessel wall stiffness. However, the effects of the combined supplementation have not been tested in individuals at greater cardiovascular disease risk. The investigators would like to show whether inorganic nitrate and vitamin C will produce greater effects on blood pressure and endothelial function when compared to inorganic nitrate alone versus the placebo treatment in people at greater risk of cardiovascular disease.
Interventions
DIETARY_SUPPLEMENTBeetroot juice plus vitamin C tablet
Concentrated beetroot juice (70 ml in the morning before breakfast and 70 ml in the evening before dinner) plus Vitamin C tablets (500mg/tablet)
DIETARY_SUPPLEMENTBeetroot juice plus placebo tablet
Concentrated beetroot juice (70ml in the morning and 70 ml in the evening) plus placebo tablets (containing 500 mg of the non-nutritive sweetener aspartame)
DIETARY_SUPPLEMENTNitrate-depleted beetroot juice plus placebo tablet
nitrate-depleted beetroot juice (70ml in the morning and 70 ml in the evening) plus placebo tablets (containing 500 mg of the non-nutritive sweetener aspartame)
Sponsors
University of Nottingham
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
50 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
* Participant is willing and able to give informed consent for participation in the study. * Participant is willing and able to comply with the requirements of the study protocol. * Non-smoking men and women. * Aged between 50-75 years. * Overweight and obese (BMI: over 25.0 kg/m2).
Exclusion criteria
* Having taken part in a research study in the last 3 months involving invasive procedures or an inconvenience allowance. * Vegetarian. * Smoking. * Resting systolic blood pressure greater than 160 mmHg; diastolic blood pressure greater than 100 mmHg. * Active cancer and any diagnosis of malignant cancer in the last 5 years. * Excessive alcohol intake (\>21 units per week). * Allergy or intolerance to the intervention food (Beetroot juice). * Diagnosis of chronic or acute metabolic and inflammatory conditions that may interfere with the study outcomes. * Major surgical operations. * Use of prescribed psychiatric drugs (antidepressants, sedatives, antipsychotics), diuretics, organic nitrates, statins and proton pump inhibitors. * Use of prescribed hormonal therapies (oestrogens, thyroxin, and progesterone), anti-hypertensive (Calcium++ channel blockers, beta-blockers, and angiotensin-converting-enzyme (ACE) inhibitors), only if the prescription had started, or the dose had been started/changed, in the previous three months. * Non-prescribed dietary supplements if not stopped at least for 2 weeks before starting the trial. * Use of the mouthwash during the study was not allowed as it interferes with the conversion of oral nitrate into nitrite.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Blood pressure | Pre, 24 hours, 48 hours and 72 hours after supplementation | Resting diastolic and systolic blood pressure using portable automated monitor |
| Cardiac function | Pre and post 3 days of supplementation | Resting cardiac function using a non-invasive methodology (Finometer) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Urinary nitrate concentration | Pre and post 3 days supplementation | Colorimetric assays based on the Griess reaction will be used to measure nitrate concentration in urine samples |
| Saliva nitrite concentration | Pre and post 3 days supplementation | Colorimetric assays based on the Griess reaction will be used to measure nitrite concentration in saliva samples |
| Flow-mediated dilation | Pre and post 3 days of supplementation | Assess endothelial function through changes in brachial artery diameter in response to reactive hyperaemia using high-resolution B-mode ultrasound. |
| Urine 8-isoprastane concentration | Pre and post 3 days supplementation | An Enzyme Linked Immuosorbant assay will be used to determine 8-isoprostane concentrations in urine. |
| Urine vitamin C concentration | Pre and post 3 days supplementation | A colorimetric assay kit will be used to measure vitamin C in urine samples |
| Saliva nitrate concentration | Pre and post 3 days supplementation | Colorimetric assays based on the Griess reaction will be used to measure nitrate concentration in saliva samples |
Countries
United Kingdom
Outcome results
None listed