Skip to main content
OpenTrials
Completed

NCT Number: NCT07242066

Effects of Dietary Nitrate and Vitamin C Co-supplementation on Blood Pressure and Endothelial Function in Overweight Individuals

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.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Blood Pressure Cardiovascular Diseases

Age range

50 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

David Greenfield Human Physiology Lab, Queens Medical Centre

Nottingham, Nottinghamshire, NG7 2UH, United Kingdom

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Beetroot juice plus vitamin C tablet

Dietary Supplement

Concentrated beetroot juice (70 ml in the morning before breakfast and 70 ml in the evening before dinner) plus Vitamin C tablets (500mg/tablet)

Beetroot juice plus placebo tablet

Dietary Supplement

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)

Nitrate-depleted beetroot juice plus placebo tablet

Dietary Supplement

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)

Primary outcomes

  1. Blood pressure

    Time frame: Pre, 24 hours, 48 hours and 72 hours after supplementation

    Resting diastolic and systolic blood pressure using portable automated monitor

  2. Cardiac function

    Time frame: Pre and post 3 days of supplementation

    Resting cardiac function using a non-invasive methodology (Finometer)

Secondary outcomes

  1. Flow-mediated dilation

    Time frame: 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.

  2. Saliva nitrate concentration

    Time frame: Pre and post 3 days supplementation

    Colorimetric assays based on the Griess reaction will be used to measure nitrate concentration in saliva samples

  3. Urinary nitrate concentration

    Time frame: Pre and post 3 days supplementation

    Colorimetric assays based on the Griess reaction will be used to measure nitrate concentration in urine samples

  4. Saliva nitrite concentration

    Time frame: Pre and post 3 days supplementation

    Colorimetric assays based on the Griess reaction will be used to measure nitrite concentration in saliva samples

  5. Urine vitamin C concentration

    Time frame: Pre and post 3 days supplementation

    A colorimetric assay kit will be used to measure vitamin C in urine samples

  6. Urine 8-isoprastane concentration

    Time frame: Pre and post 3 days supplementation

    An Enzyme Linked Immuosorbant assay will be used to determine 8-isoprostane concentrations in urine.

Sponsors and collaborators

Lead sponsor

University of Nottingham

Other

Registry information

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Nov 21, 2025
Registry last updated
Dec 2, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.