Effect of Beet Juice Supplementation on Vascular and Inspiratory Muscle Function

Older adults with coronary artery disease (CAD) have impaired vascular and inspiratory muscle function. The overarching goal of this double-blind, randomized, crossover, placebo-controlled pilot trial was to inform the development of a fully powered trial to evaluate the effects of dietary nitrate supplementation in older adults with CAD. We aimed to address the following objectives: (a) assess the feasibility, tolerability, and safety of the study protocol; (b) gather preliminary evidence on the effects of nitrate-rich beetroot juice compared with nitrate-depleted beetroot juice (placebo), and estimate the effect sizes; and (c) determine if a full-scale definitive trial is justified.

Study Overview

• Status: Completed
• Conditions: Coronary Artery Disease
• Intervention / Treatment: Dietary supplement: Nitrate rich beetroot juice; Dietary supplement: Nitrate depleted beetroot juice

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Florida
    • Gainesville, Florida, United States, 32611
      • Integrative Cardiovascular Physiology Laboratory, University of Florida

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults with coronary artery disease (CAD) based on an angiogram >50% stenosis in any major epicardial vessel or history of myocardial infarction or history of coronary revascularization.
• Considered to have stable CAD on optimal medical therapy
• 60 to 85 years of age
• Males and females (females must be postmenopausal either natural or surgical)
• Able to give consent

Exclusion Criteria:

• Unstable angina, recent myocardial infarction or heart failure within 6 months
• Coronary revascularization, including percutaneous coronary intervention and coronary artery bypass graft or thoracic surgery within 6 months.
• Stroke, obstructive pulmonary disease, hepatitis B, C, HIV, seizures, or other relevant ongoing or recurrent illness
• Individuals who have participated in respiratory training within the last 12 months or cardiac rehabilitation within the last 6 months
• Uncontrolled hypertension
• Use of tobacco products including smoking traditional or e-cigarettes
• Use of hormone replacement therapy in women or men (e.g., estrogen, progesterone or testosterone)
• Unwilling to stop using mouthwash at least 1 week before the start of the study and during study participation
• Unwilling to remain weight stable during study participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Nitrate rich beetroot juice	Dietary supplement: Nitrate rich beetroot juice; Participants will drink nitrate rich beetroot juice (2.4 floz ; Beet It Sport Nitrate 400 concentrated beetroot shot; James White Drink, ltd) twice daily for two weeks.
Placebo Comparator: Nitrate depleted beetroot juice	Dietary supplement: Nitrate depleted beetroot juice; Participants will drink nitrate depleted beetroot juice (2.4 floz ; Beet It placebo concentrated beetroot shot; James White Drink, ltd) twice daily for two weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in endothelial function	Endothelial function will be determined using brachial artery flow-mediated dilation via high resolution duplex ultrasonography. Reactive hyperemia will be produced by inflating a forearm cuff to ~250 mmHg for 5 minutes followed by rapid deflation.	Baseline up to following 2 weeks of experimental condition
Change in inspiratory muscle function	Inspiratory muscle function including strength, power and endurance will be assessed using the POWERbreathe KH2 device	Baseline up to following 2 weeks of experimental condition

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in microvascular function	Microvascular function will be assessed using the forearm blood flow response to submaximal handgrip exercise. Brachial artery blood flow and diameter will be assessed using ultrasound.	Baseline up to following 2 weeks of experimental condition
Change in central arterial stiffness	The SphygmoCor XCEL device will be used to measure carotid to femoral pulse wave velocity.	Baseline up to following 2 weeks of experimental condition
Change in central arterial hemodynamics	The SphygmoCor XCEL device will be used to obtain central pulse wave analysis.	Baseline up to following 2 weeks of experimental condition
Change in functional capacity	Using the Duke Activity Status Index we will assess participants' ability to perform daily activities.	Baseline up to following 2 weeks of experimental condition

Collaborators and Investigators

• Sponsor: University of Florida

Study record dates

Study Major Dates

• Study Start (Actual): November 12, 2021
• Primary Completion (Actual): August 28, 2025
• Study Completion (Actual): August 28, 2025

Study Registration Dates

• First Submitted: May 27, 2021
• First Submitted That Met QC Criteria: June 3, 2021
• First Posted (Actual): June 10, 2021

Study Record Updates

• Last Update Posted (Actual): May 14, 2026
• Last Update Submitted That Met QC Criteria: May 12, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Heart Diseases; Arteriosclerosis; Arterial Occlusive Diseases; Coronary Disease; Myocardial Ischemia; Coronary Artery Disease
• Other Study ID Numbers: IRB202100040

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No