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

NCT ID: NCT07242066

Last Updated: 2025-12-02

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 15 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-11-25
• Study Completion Date: 2025-08-22

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.

Conditions

Blood Pressure

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: DOUBLE

Study Groups

Placebo

Placebo beetroot juice and tablet

Group Type: PLACEBO_COMPARATOR

Nitrate-depleted beetroot juice plus placebo tablet

Intervention Type: 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)

Beetroot juice + Vitamin C

Beetroot juice and Vitamin C

Group Type: EXPERIMENTAL

Beetroot juice plus vitamin C tablet

Intervention Type: 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 + placebo

Beetroot juice + placebo tablet

Group Type: EXPERIMENTAL

Beetroot juice plus placebo tablet

Intervention Type: 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)

Interventions

Beetroot 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)

Intervention Type: DIETARY_SUPPLEMENT

Beetroot 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)

Intervention Type: DIETARY_SUPPLEMENT

Nitrate-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)

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

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.

• Minimum Eligible Age: 50 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

University of Nottingham

OTHER

Sponsor Role: lead

Responsible Party

Kostas Tsintzas

Professor of Human Physiology

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

David Greenfield Human Physiology Lab, Queens Medical Centre

Nottingham, Nottinghamshire, United Kingdom

Countries

United Kingdom

References

Deanfield JE, Halcox JP, Rabelink TJ. Endothelial function and dysfunction: testing and clinical relevance. Circulation. 2007 Mar 13;115(10):1285-95. doi: 10.1161/CIRCULATIONAHA.106.652859. No abstract available.

Reference Type: BACKGROUND

PMID: 17353456 (View on PubMed)

Forstermann U. Nitric oxide and oxidative stress in vascular disease. Pflugers Arch. 2010 May;459(6):923-39. doi: 10.1007/s00424-010-0808-2. Epub 2010 Mar 21.

Reference Type: BACKGROUND

PMID: 20306272 (View on PubMed)

Gori T, Munzel T. Oxidative stress and endothelial dysfunction: therapeutic implications. Ann Med. 2011 Jun;43(4):259-72. doi: 10.3109/07853890.2010.543920. Epub 2011 Feb 1.

Reference Type: BACKGROUND

PMID: 21284528 (View on PubMed)

Other Identifiers

FHMS 128-0224

Identifier Type: -

Identifier Source: org_study_id