The Effect of Dietary Nitrate on the Oral Microbiome

Not Applicable

Completed

• Conditions: Identify Oral Bacteria Responsible for Nitrate Reduction; Cardiovascular Health
• Interventions: Dietary Supplement: Nitrate-rich beetroot juice; Dietary Supplement: Nitrate-depleted beetroot juice; Other: Mouthwash

• Registration Number: NCT03467061
• Lead Sponsor: University of Exeter

Brief Summary

This study evaluates whether dietary manipulation of the oral microbiota modulates cardiovascular health through effects on nitric oxide bioavailability.

Detailed Description

Nitric oxide is an important molecule for human health because it controls blood flow and blood pressure. With aging, our ability to make nitric oxide gets worse and our blood pressure tends to increase. We can help the body produce more nitric oxide by supplementing the diet with vegetables, such as beetroot juice, which contains high amounts of nitrate. This has been shown to improve blood flow and blood pressure. The bacteria inside our mouths play an important role in helping convert the ingested nitrate to nitric oxide. The reason for this study is to find out whether there are differences in oral bacteria between young and older adults, and how the oral bacterial community and blood flow and blood pressure might change when diet is supplemented with natural, nitrate-rich beetroot juice and when we use antibacterial mouthwash. This study will help us understand how the bacteria inside our mouths might be useful for keeping us healthy.

Study Timeline

• Study First Submitted: 2017-12-19
• Study Start: 2018-01-10
• Study First Submitted QC: 2018-03-14
• Study First Posted: 2018-03-15
• Status Verified: 2021-05
• Primary Completion: 2021-05-06
• Study Completion: 2021-05-06
• Last Update Submitted: 2021-05-26
• Last Update Posted: 2021-05-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 101

Inclusion Criteria

• Healthy young (18-30 yr) and older adults (65-80 yr)
• Male and female
• Willing to undergo the experiments as detailed in the informed consent documentation
• Willing and capable of providing written, informed consent.

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Exclusion Criteria

• Individuals receiving medication for pulmonary, cardiovascular, or metabolic conditions, ulcerative colitis or renal disease
• Having an active oral disease or dentures
• Having resting BP >140/90 mmHg
• Having used antibiotics within 3 months
• Lacking willingness or capacity to give informed consent.

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Nitrate-rich beetroot juice	Nitrate-rich beetroot juice	2 x 70mL concentrated juice per day for 14 days
Nitrate-depleted beetroot juice	Nitrate-depleted beetroot juice	2 x 70mL concentrated juice per day for 14 days
Antibacterial mouthwash	Mouthwash	2 x 10mL antibacterial mouthwash per day for 14 days

Primary Outcome Measures

Name	Time	Method
Quantity of nitrate -reducing bacteria	14 days	Change in total quantity of nitrate-reducing bacteria as measured by sequencing bacterial 16S rRNA genes

Secondary Outcome Measures

Name	Time	Method
Flow mediated dilation	14 days	Change in flow mediated dilation
Nitric oxide bioavailability - salivary nitrate	14 days	Change in nitrate concentration of saliva as measured by ozone-based chemiluminescence
Nitric oxide bioavailability - salivary nitrite	14 days	Change in nitrite concentration of saliva as measured by ozone-based chemiluminescence
Nitric oxide bioavailability - plasma nitrate	14 days	Change in nitrate concentration of plasma as measured by ozone-based chemiluminescence
Blood pressure	14 days	Change in systolic and diastolic BP
Nitric oxide bioavailability - plasma nitrite	14 days	Change in nitrite concentration of plasma as measured by ozone-based chemiluminescence

Trial Locations

Locations (1)

Diabetes & Vascular Medicine Research Centre, Clinical Research Facility; 🇬🇧 Exeter, Devon, United Kingdom