Influence of Dietary Nitrate on Vascular Dysfunction and Inflammation

A Double-blind, Randomised, Placebo-controlled Parallel Study to Investigate the Effect of Dietary Nitrate on a Model of Vascular Dysfunction in Healthy Volunteers

The principal research objective is to determine whether inorganic nitrate in the form of beetroot juice compared to placebo control prevents the systemic inflammation that underlies typhoid vaccine-induced endothelial dysfunction

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases
• Intervention / Treatment: Biological: Typhoid vaccine; Dietary supplement: Concentrate beetroot Juice; Dietary supplement: Concentrate beetroot Juice (Placebo)

Detailed Description

We wish to determine in a prospective manner whether inorganic nitrate affects the endothelial dysfunction induced by systemic inflammation. At baseline we will measure flow-mediated dilatation (FMD) and peripheral augmentation index, as well as aortic stiffness, as measured by pulse wave velocity (PWV). Volunteers will then receive ~8 mmols of dietary nitrate or nitrate free placebo juice once daily for 6 days. After this, depending on availability, volunteers will receive a typhoid vaccine Typherix®, GlaxoSmithKline UK or Typhim Vi ™, AAH Pharmaceuticals Ltd). This vaccine generates a mild systemic inflammation that is associated with vascular dysfunction. All vascular function measures will be repeated at 8 hours and 32 hours after vaccine administration.

• Study Type: Interventional
• Enrollment (Actual): 78
• Phase: Phase 1

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, EC1M 6BQ
    • William Harvey Research Institute, Barts and The London School of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 43 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

1. Healthy volunteers
2. Aged 18-45
3. Volunteers who are willing to sign the consent form.
4. Normal resting blood pressure (<140/90 mmHg)

Exclusion Criteria:

1. Healthy subjects unwilling to consent
2. Pregnant, or any possibility that a subject may be pregnant unless in the latter case a pregnancy test is performed with a negative result
3. History of any serious illnesses, including recent infections or trauma
4. Subjects taking systemic medication (other than the oral contraceptive pill)
5. Subjects with self-reported use of mouthwash or tongue scrapes
6. Subjects with recent (3 months) or current antibiotic use
7. Subjects with a history, or recent treatment of (within last 3 months) any oral condition (excluding caries), including gingivitis, periodontitis and halitosis
8. Subjects with a history of typhoid vaccination in the last 6 months
9. Subjects with any history of a blood-borne infectious disease such Hepatitis B or C virus, or HIV

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Nitrate-rich beetroot juice; Biological: Typhoid vaccine The typhoid vaccine is composed of purified polysaccharide from S. typhi capsule 25 micrograms contained in 0.5 ml solution Other Name: Typhim Vi® Dietary Supplement: Concentrate beetroot Juice 140 ml containing ~8 mmol of inorganic nitrate	Biological: Typhoid vaccine; The typhoid vaccine is composed of purified polysaccharide from S. typhi capsule 25 micrograms contained in 0.5 ml solution; Other Names: Typhim Vi®; Dietary supplement: Concentrate beetroot Juice; 140 ml containing ~8 mmol of inorganic nitrate
Placebo Comparator: Nitrate-deplete beetroot juice; Biological: Typhoid vaccine The typhoid vaccine is composed of purified polysaccharide from S. typhi capsule 25 micrograms contained in 0.5 ml solution Other Name: Typhim Vi® Dietary Supplement: Concentrate beetroot Juice 140 ml which is nitrate-depleted	Biological: Typhoid vaccine; The typhoid vaccine is composed of purified polysaccharide from S. typhi capsule 25 micrograms contained in 0.5 ml solution; Other Names: Typhim Vi®; Dietary supplement: Concentrate beetroot Juice (Placebo); 140 ml which is nitrate-depleted

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Flow mediated dilatation	Comparison of change in FMD from baseline after typhoid vaccination following inorganic nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)
Plasma nitrite concentration	Comparison of change in plasma nitrite concentration following inorganic nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Markers of acute inflammation	Comparison of change in peripheral markers of inflammation and leucocyte count following nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)
Pulse wave velocity	Comparison of change in PWV from baseline after typhoid vaccination following nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)
Platelet reactivity	Comparison of change in platelet reactivity from baseline after typhoid vaccination following nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)
Plasma nitrate concentration	Comparison of change in plasma nitrate concentration following inorganic nitrate versus placebo supplementation	Day 1, Day 7 (8 hours post typhoid vaccine), Day 8 (32 hours post typhoid vaccine)

Collaborators and Investigators

• Sponsor: Queen Mary University of London
• Investigators: Principal Investigator: Amrita Ahluwalia, BSc PhD, William Harvey Research Institute, Barts and The London, Queen Mary's School of Medicine and Dentistry

Publications and helpful links

General Publications

• Clapp BR, Hingorani AD, Kharbanda RK, Mohamed-Ali V, Stephens JW, Vallance P, MacAllister RJ. Inflammation-induced endothelial dysfunction involves reduced nitric oxide bioavailability and increased oxidant stress. Cardiovasc Res. 2004 Oct 1;64(1):172-8. doi: 10.1016/j.cardiores.2004.06.020.
• Hingorani AD, Cross J, Kharbanda RK, Mullen MJ, Bhagat K, Taylor M, Donald AE, Palacios M, Griffin GE, Deanfield JE, MacAllister RJ, Vallance P. Acute systemic inflammation impairs endothelium-dependent dilatation in humans. Circulation. 2000 Aug 29;102(9):994-9. doi: 10.1161/01.cir.102.9.994.
• Kharbanda RK, Walton B, Allen M, Klein N, Hingorani AD, MacAllister RJ, Vallance P. Prevention of inflammation-induced endothelial dysfunction: a novel vasculo-protective action of aspirin. Circulation. 2002 Jun 4;105(22):2600-4. doi: 10.1161/01.cir.0000017863.52347.6c.
• Donald AE, Charakida M, Cole TJ, Friberg P, Chowienczyk PJ, Millasseau SC, Deanfield JE, Halcox JP. Non-invasive assessment of endothelial function: which technique? J Am Coll Cardiol. 2006 Nov 7;48(9):1846-50. doi: 10.1016/j.jacc.2006.07.039. Epub 2006 Oct 17.

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2016
• Primary Completion (Actual): December 1, 2020
• Study Completion (Actual): August 1, 2021

Study Registration Dates

• First Submitted: March 16, 2016
• First Submitted That Met QC Criteria: March 16, 2016
• First Posted (Estimate): March 22, 2016

Study Record Updates

• Last Update Posted (Actual): July 20, 2022
• Last Update Submitted That Met QC Criteria: July 19, 2022
• Last Verified: July 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases
• Other Study ID Numbers: 15/LO/0789