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Effects of Daily Nitrate Consumption on Oral Bacteria Composition, Blood Pressure and Vascular Function (REBOC2)

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ClinicalTrials.gov Identifier: NCT03784742
Recruitment Status : Not yet recruiting
First Posted : December 24, 2018
Last Update Posted : December 24, 2018
Sponsor:
Collaborator:
Saudi Cultural Bureau
Information provided by (Responsible Party):
Julie Lovegrove, University of Reading

Brief Summary:
Diseases of the heart and blood vessels, including raised blood pressure, are one of the leading causes of death worldwide. Higher intakes of dietary nitrate, found abundantly in root vegetables such as beetroot, have been shown to have health benefits including lowering blood pressure and improving the elasticity of blood vessels. Bacteria which reside in the mouth and those in the gastrointestinal tract play an important role in converting dietary nitrate to nitrite and nitric oxide (a chemical which promotes the relaxation of blood vessels). In particular, removal of oral bacteria by using antiseptic mouthwash is accompanied by an increase in blood pressure in subjects with normal blood pressure, even after consuming nitrate-rich foods. To date, very little is known about the role of these oral bacteria in the control of blood pressure, and if there are any differences in bacterial composition between individuals.

Condition or disease Intervention/treatment Phase
No Dental Disease Non-smoking Other: Nitrate rich beetroot juice Other: Placebo beetroot juice Not Applicable

Detailed Description:

Interested volunteers will be provided with an outline of the study and asked to complete a medical and lifestyle questionnaire (in person, by email or over the phone). Potentially suitable participants will be identified and asked to attend a screening session after a 12 h overnight fast (not eating during this time and only drinking water) during which the study will be explained in more detail before a consent form is signed. Anthropometric measurements will then be taken including weight, height and blood pressure. A 9 ml blood sample will also be collected on site at the Department of Food and Nutritional Sciences (Hugh Sinclair Unit of Human Nutrition). Subjects who meet the initial inclusion criteria will be invited to a further screening session during which time a dentist will check for dental diseases (e.g. current dental cavities or periodontal infection) and saliva flow rate. Volunteers without periodontal disease and with normal saliva flow will then be invited to participate in the study.

Eligible subjects will then be randomised to one of two treatments: i) up to 70 ml (the amount given will be equivalent to 3.7 mg/kg body weight) beetroot juice (James White Drinks Limited, UK) or ii) a matched volume of placebo beetroot juice (control, James White Drinks Limited, UK) to be consumed daily for 8 weeks. As drinking water is a major source of dietary nitrate, subjects will be provided with a water filter to reduce the nitrate level in their tap water for drinking and cooking during the study period. There will be a wash out period of 4 weeks between the intervention juices. In total, volunteers will be involved in the study for 20 weeks (five months).

On the day before each baseline study visit (weeks 0 and 12), volunteers will be required to fast overnight after having a low nitrate evening meal and only drinking low nitrate mineral water (Buxton mineral water), which will be provided to them, during this time. They will refrain from strenuous exercise and alcohol. On the morning of the study visit, the volunteers will be asked not to brush their teeth before they come to the clinical unit for their study visit.

When they arrive in the fasted state, the participants will be asked to provide a spot urine sample and a stool sample. Body weight and composition will be measured using the Tanita weighing scale, saliva sample and an oral bacteria sample will be collected by swabbing the tongue with a cotton swab. Volunteers will be asked to lie down for 20 minutes prior to the measurement of blood pressure and pulse wave analysis (PWA) using the Mobil-O-Graph device followed by the assessment of microvascular reactivity using Laser Doppler Imaging with iontophoresis. A blood sample of 20 ml (equivalent to just over 1 tablespoon) will then be taken before a light breakfast is provided. Volunteers will then be given a toothbrush and toothpaste to brush their teeth and asked to complete an online food frequency questionnaire (EatwellUK).

During the four-week wash-out period between interventions, participants will be instructed to avoid any beetroot juice drinks and maintain their usual dietary and lifestyle habits.


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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 28 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Treatment
Official Title: Investigation of the Effects of Daily Nitrate Consumption on Oral Bacteria Composition, Blood Pressure and Vascular Functio
Estimated Study Start Date : December 2018
Estimated Primary Completion Date : August 2019
Estimated Study Completion Date : December 2019

Arm Intervention/treatment
Active Comparator: Nitrate-rich Beetroot juice
Nitrate-rich beetroot juice equivalent to 3.7 mg nitrate per kg body weight daily for 8 weeks.
Other: Nitrate rich beetroot juice
James White Drinks Limited beetroot juice (0.4-0.45 g nitrate/70 ml drink).

Placebo Comparator: Placebo beetroot juice
Placebo beetroot juice (equivalent volume to the amount of nitrate-rich beetroot juice consumed) daily for 8 weeks.
Other: Placebo beetroot juice
James White Drinks Limited Placebo beetroot juice (0 nitrate/70 ml drink).




Primary Outcome Measures :
  1. Change in blood pressure measure [ Time Frame: Before and after each 8 week intervention ]
    Systolic blood pressure, diastolic blood pressure and pulse pressure

  2. Change in oral bacteria composition [ Time Frame: Before and after each 8 week intervention ]
    Oral bacteria composition determined using next generation sequencing.


Secondary Outcome Measures :
  1. Change in vascular reactivity [ Time Frame: Before and after each 8 week intervention ]
    Laser Doppler Imaging with iontophoresis.

  2. Change in Nox concentrations in serum, urine and saliva [ Time Frame: Before and after each 8 week intervention ]

    Nitrate and nitrite concentrations will be determined using high performance liquid chromatography in plasma, urine and saliva. Nitric oxide will be calculated as the sum of nitrate and nitrite concentrations.

    Creatinine will be measured in the urine samples to normalise the nitrate and nitrite concentrations in urine for hydration status.


  3. Change in gut bacteria composition [ Time Frame: Before and after each 8 week intervention ]
    Stool sample will be analysed to determine composition using next generation sequencing will be used to find the differences between treatments.

  4. Change in fasting lipid profile [ Time Frame: Before and after each 8 week intervention ]
    Total cholesterol, HDL-C, and triacylglycerol will be measured using a clinical chemistry analyser. LDL-C will be calculated using the Friedewald formula.

  5. Change in C-reactive protein [ Time Frame: Before and after each 8 week intervention ]
    C-reactive protein will be measured using a clinical chemistry analyser

  6. Change in endothelial function [ Time Frame: Before and after each 8 week intervention ]
    Pulse wave analysis will be measured using Mobil-O-Graph

  7. Change in body weight [ Time Frame: Before and after each 8 week intervention ]
    Body weight will be measured using a Tanita scale

  8. Height measurement [ Time Frame: Before the intervention ]
    Height will be measured using a stadiometer

  9. Change in body mass index [ Time Frame: Before and after each 8 week intervention ]
    Body mass index will be calculated from the body weight and height measurement

  10. Change in insulin [ Time Frame: Before and after each 8 week intervention ]
    Insulin levels will be measured by ELISA

  11. Change in glucose [ Time Frame: Before and after each 8 week intervention ]
    Glucose levels will be measured using a clinical chemistry analyser

  12. Change in insulin sensitivity [ Time Frame: Before and after each 8 week intervention ]
    Glucose and insulin measurements will be used to calculate the homeostatic model assessment of insulin resistance (HOMA-IR)



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Ages Eligible for Study:   18 Years to 64 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

Male and female;

  • A signed consent form;
  • Blood pressure <140/90 mm Hg;
  • BMI range 18.5 - 39.9 kg/m2;
  • Age 18-64 years;
  • Non-smoking;
  • Not taking blood pressure lowering medication or using medications known to influence vascular function such as a glyceryl trinitrate (GTN) spray;
  • No recent (within 3 months) or current use of antibiotics.

Exclusion criteria are:

Diagnosed with a chronic illness;

  • Anaemia defined as a haemoglobin < 115 g/l for women and <130 g/l for men;
  • Individuals with food allergies or allergies to medicated mouthwash or ingredients in the oral products;
  • Requirements to take long-term medication active on the oral cavity including prebiotics and probiotics or have taken antibiotics within the last 3 months;
  • Gingivitis diagnosis, or periodontal disease or chronic oral complaints or existing oral pathology.
  • Less than four natural (enamel) buccal surfaces of upper molars available;
  • Presence of fixed or removable oral appliances (e.g., dentures, orthodontic wires); xerostomia (a persistent dry mouth) diagnosis;
  • Current smoker;
  • Already participating in a dietary intervention study or clinical trial;
  • Excessive alcohol consumption (> 14 units/wk);
  • Females who are pregnant or lactating;
  • Individuals not willing to give up using mouthwash or change their dental hygiene routine. Regular consumption or use of xylitol-based products such as toothpaste and chewing gum.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03784742


Contacts
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Contact: Julie A Lovegrove, BSc, PhD 0044118378 ext 6418 j.a.ovegrove@reading.ac.uk
Contact: Hayat S Alzahrani, MSc 07496966022 h.s.alzahrani@pgr.reading.ac.uk

Locations
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United Kingdom
Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading Not yet recruiting
Reading, Berkshire, United Kingdom, RG6 6AP
Contact: Julie Lovegrove, Professor    0044(0)1183786418    j.a.lovegrove@reading.ac.uk   
Contact: Kim Jackson, PhD    0118378 ext 5361    k.g.jackson@reading.ac.uk   
Sponsors and Collaborators
University of Reading
Saudi Cultural Bureau
Investigators
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Principal Investigator: Julie A Lovegrove, BSc, PhD University of Reading

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Responsible Party: Julie Lovegrove, Professor of Human Nutrition, Head of the Hugh Sinclair Unit of Human Nutrition, University of Reading
ClinicalTrials.gov Identifier: NCT03784742     History of Changes
Other Study ID Numbers: 347890
First Posted: December 24, 2018    Key Record Dates
Last Update Posted: December 24, 2018
Last Verified: December 2018

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Stomatognathic Diseases