Nitrite Supplementation in Long COVID Patients

March 14, 2025 updated by: VA Office of Research and Development

Nitrite Supplementation to Mitigate Fatigability and Increase Function in Long COVID Patients

Potential benefits of a nitrate-rich juice supplement to improve skeletal muscle function and associated physical capacity will be studied in patients with Long COVID. Consenting patients with Long-COVID will be randomized to receive Beet-It nitrate beverage group versus a nitrate-depleted placebo beverage. Both groups will receive physical therapy at the long COVID Clinic at VAPHS with therapeutic goals to improve strength, balance, inspiratory, and aerobic capabilities. Physical therapy will last for 2 weeks and include 2 or 3 sessions with a physical therapist a week depending on each individual's exercise tolerance. These sessions can take place on-site or at home (or a hybrid combination) All participants will undergo functional assessments and tissue assessments before and after the 14-day study intervention.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

In a proof of concept pilot, the investigators will study 30 Veterans with long COVID, comparing 15 who consume two weeks of daily nitrate-rich beetroot juice versus matched Veterans who consume a nitrate-depleted placebo. Nitrate is metabolized to increase cellular nitric oxide once it is ingested. Nitric oxide (NO) is a signaling molecule that contributes to numerous physiological functions, including enhanced skeletal muscle mitochondrial respiration, which may thereby lead to decreased fatigability and increased physical function. NO is commonly produced from the conversion of the amino acid L-arginine to L-citrulline in the presence of oxygen. However, inorganic nitrate provided as a dietary supplement can serve as an additional substrate for bioactive nitrite and downstream NO, particularly during the ischemic stress of exercise. In this study, consenting patients with Long-COVID will be randomized to receive Beet-It nitrate beverage group as a source of inorganic nitrites and NO, versus a nitrate-depleted placebo beverage. Both groups will undergo simultaneous physical therapy. Primary endpoints center on meaningful clinical changes, including fatigability (i.e., rating of perceived exertion during steady-state walking), cardiorespiratory fitness (i.e., peak oxygen utilization [VO2] as well as submaximal VO2 at anaerobic threshold [VAT]). In addition, serology and skeletal muscle assessments will include nitrate and nitrite levels and mitochondrial respiration to analyze nitrite-mediated mechanisms underlying functional changes.

Principal investigator Daniel Forman, MD has developed expertise in nitrite therapeutics using nitrite capsule supplements for older sedentary adults in relation to sedentariness and heart failure. This SPiRE proposal focuses nitrite therapeutics to both younger and older adults with long COVID.

Aims: We will conduct a pilot randomized controlled trial to study the benefits of nitrate-rich beetroot juice versus placebo in 30 Veterans with a diagnosis of Long COVID. All participants will receive a daily study juice intervention for 2 weeks. All participants will be encouraged to participate in the standard physical therapy program in the Long COVID clinic.

Aim 1: To study the efficacy of nitrate-rich juice supplementation to reduce fatigability as measured by rating of perceived exertion (RPE) during submaximal steady-state 1.5 mile per hour walking after two weeks of treatment in patients with Long Covid. Walking efficiency (VO2 per kg) will also be assessed in association with fatigability.

Aim 2: To study the benefits of nitrate-rich juice supplementation to increase cardiorespiratory fitness (peak oxygen utilization [VO2], VO2 at anaerobic threshold (VAT), 400-meter corridor walk (400MCW), short physical performance battery (SPPB) in patients with Long COVID after two weeks of treatment.

Aim 3: To explore the utility of nitrate-rich juice supplementation to enhance skeletal muscle mitochondrial respiration in patients with Long COVID as measured by ex vivo Oroboros analysis.

Study Type

Interventional

Enrollment (Actual)

17

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Pennsylvania
      • Pittsburgh, Pennsylvania, United States, 15240
        • VA Pittsburgh Healthcare System University Drive Division, Pittsburgh, PA

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Veterans with prior COVID-19, with residual symptoms of long COVID including increased fatigability.
  • Inclusion limited to age 18 and over

Exclusion Criteria:

  • Blood pressure <110/60 mmHg, either systolic or diastolic value which may affect participant safety during assessments will be at the discretion of the study physician
  • Unable to hold warfarin, novel oral anticoagulants (NOACs) or aspirin for 3 days prior to muscle biopsy, or to hold thienopyridine medications for 5 days prior to muscle biopsy
  • Current use of organic nitrates or phosphodiesterase type 5 (PDE5) inhibitors
  • Orthopedic or other chronic condition which limits physical activity or functional testing assessments
  • End-stage disease
  • Dementia or other reason unable to give informed consent
  • Anemia (hemoglobin <11.0 g/dL in men or hemoglobin <10.0 g/dL in women)
  • Unstable psychiatric diagnosis
  • Clinically significant alcohol intake or substance abuse
  • Chronic use of oral corticosteroids or medications that affect muscle function
  • Use of anti-bacterial mouthwash or antacids that confound the nitrate/nitrite/NO pathway.
  • Suicidal ideations
  • Unwilling to hold Viagra-like drugs (i.e. Viagra, Cialis, Levitra, other phosphodiesterase inhibitors)
  • Involved in another greater than minimal risk study
  • Other clinically unstable medical condition as determined by the study physician

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Beet-It nitrate beverage

Participant will receive 140 ml per day of Beet-It nitrate beverage for for 14 days. All participants will be encouraged to undergo physical therapy 2-3 times per week based on tolerance for activity and recovery needed after each session. Physical therapy will be standardized to include strength, balance, inspiratory muscle training, and aerobic training.

Participants randomized to this arm will be assessed at baseline and follow-up visits on all outcome measures.
Dietary supplement: 140 ml per day of Beet-It nitrate beverage (James White Drinks Ltd., Ipswich, UK)
The investigators propose to study the benefits nitrite therapeutics, using nitrate-rich beetroot juice to increase serum nitrite. The investigators hypothesize that increased nitrite will improve functional metrics and reduce fatigability in Veterans with long COVID as a result of enhanced skeletal muscle mitochondrial respiration. Participant will receive 140 ml per day of Beet-It nitrate beverage for 16 mmol of nitrate/day for 14 days vs the placebo.
Placebo Comparator: Nitrate-depleted placebo

Participants will receive 210 ml of nitrate-depleted placebo for 14 days. All participants will be encouraged to undergo physical therapy 2-3 times per week based on tolerance for activity and recovery needed after each session. Physical therapy will be standardized to include strength, balance, inspiratory muscle training, and aerobic training.

Participants randomized to this arm will be assessed at baseline and follow-up visits on all outcome measures.
Dietary supplement: 210 ml of nitrate-depleted placebo
Participants randomized to the placebo arm will receive 210 ml of nitrate-depleted beverage (cranberry juice) per day for 14 days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fatigability
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Rating of Rate of Perceived Exertion (RPE) during the 5th minute of a 5-min of a 1.5 mile per hour steady-state treadmill walking test is used as an assessment of fatigability. RPE scale is from 6 (no physical exertion) - 20 (maximal exertion/very hard).
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Walking Efficiency
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Walking efficiency (VO2/kg) is assessed by incorporating VO2 assessments during the 5-min steady-state walking protocol. This is assessed using cardiopulmonary exercise testing (CPET) equipment. A lower VO2 for the same functional workload indicates improved efficiency.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
400m Corridor Walk Test (400MCW)
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
This test measures the amount of time it takes the participant to walk a 400-meter course to assess cardiovascular and pulmonary fitness or to predict adverse outcomes such as mobility disability.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Short Performance Physical Battery (SPPB)
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
The SPPB is a test of balance, gait, strength, and endurance that combines gait speed, chair stand and balance tests. SPPB scaled score ranges from 0 - 12. Scores of 0 indicate that the participant is unable/barely able to perform the tasks, while 12 indicates they completed all tasks optimally.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Mitochondrial Respiration
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
To determine the impact of nitrite-rich juice supplementation on skeletal muscle mitochondrial respiration on patients with Long COVID, muscle biopsy of the vastus lateralis will be completed at baseline and following 2 weeks of supplementation. At each time point muscle respiratory capacity will be measured using the Oroboros-2k system. The main outcome will be state 3 respiration (maxOXPHOS, pmol/mg/min wet.wt.). Data will be reported as Mean +/- standard deviation.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Peak oxygen utilization (VO2) non-normalized
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Peak VO2 (ml/min) non-normalized to weight will be collected using symptom-limited cardiopulmonary exercise testing (CPET).
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
VO2 at anaerobic threshold (AT) non-normalized
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
VO2 (ml/min) non-normalized at AT will be assessed using symptom-limited CPET. The VO2 at AT for the general population occurs at approximately 50-60% of the peak VO2.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Veterans RAND-12 (VR-12)
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
The Veterans RAND-12 (VR-12) is a brief, multi-use, self-administered health survey comprised of 12 items. The instrument is primarily used to measure health related quality of life, to estimate disease burden, and to evaluate disease-specific benchmarks. There are two score components: a Physical Component Score a Mental Component Score. The scores are a standardized t-score with mean of 50 and standard deviation of 10.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Peak oxygen utilization (VO2) normalized to weight
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Peak VO2 will be collected using symptom-limited cardiopulmonary exercise testing (CPET). The average sedentary male will achieve a peak VO2 of approximately 35 to 40 mL/kg/min. The average sedentary female will score a VO2 max of between 27 and 30 mL/kg/min.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Serum Nitrate
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
5 ml of blood will be collected from participants and spun down using a centrifuge to separate the plasma from the rest of the blood. Serological sampling is completed at baseline and at final visit. Serum nitrite (µmol/L) and nitrate levels (µmol/L) will be measured at baseline and after the study intervention to evaluate the successful metabolism of nitrate (in beetroot juice) to nitrite.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
VO2 at anaerobic threshold (AT) normalized to weight
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
VO2 (ml/kg/min) at AT will be assessed using symptom-limited CPET. The VO2 at AT for the general population occurs at approximately 50-60% of the peak VO2.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
Serum Nitrite
Time Frame: Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks
5 ml of blood will be collected from participants and spun down using a centrifuge to separate the plasma from the rest of the blood. Serological sampling is completed at baseline and at final visit. Serum nitrite (µmol/L) and nitrate levels (µmol/L) will be measured at baseline and after the study intervention to evaluate the successful metabolism of nitrate (in beetroot juice) to nitrite.
Baseline (pre-intervention) to Follow-up (post-intervention); approx. 2 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

VA Office of Research and Development

Collaborators

University of Pittsburgh

Investigators

  • Principal Investigator: Daniel E Forman, MD, VA Pittsburgh Healthcare System University Drive Division, Pittsburgh, PA

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2023

Primary Completion (Actual)

February 12, 2025

Study Completion (Actual)

February 14, 2025

Study Registration Dates

First Submitted

November 14, 2022

First Submitted That Met QC Criteria

November 14, 2022

First Posted (Actual)

November 16, 2022

Study Record Updates

Last Update Posted (Actual)

March 25, 2025

Last Update Submitted That Met QC Criteria

March 14, 2025

Last Verified

March 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • F4409-P
  • 1I21RX004409 (U.S. NIH Grant/Contract)

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

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Long COVID

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Italy

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe