Does Taurine Supplementation Improve Vascular Function and Orthostatic Responses in Long COVID?

June 3, 2026 updated by: Heather Edgell, York University
Millions have developed Long COVID (LC), and recent findings show an association between taurine deficiency (an amino acid) and symptoms in LC. Cost-effective and accessible interventions are needed to improve welfare and reduce healthcare costs. We will investigate the efficacy of 12-weeks of taurine supplementation (self-administered), on vascular function and the cardio/cerebrovascular responses to upright posture. We will measure resting vascular function with an EndoPAT device, resting heart rate variability, and the blood pressure, heart rate, and brain blood flow responses to 5 minutes of head-up tilt before and after weeks of taurine supplementation in LC. We hypothesize that the 12 weeks of supplementation will improve both resting vascular function and the responses to upright tilt. In turn, we hypothesize that symptoms will also improve (as measured by questionnaires).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Millions of people have been infected by SARS-CoV-2, or COVID-19, and recent estimates suggest that up to 13% have developed Long COVID [1]. The World Health Organization defines Long COVID as "the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation." SARS-CoV-2 is known to use angiotensin converting enzyme 2 (ACE2) to enter cells [2], and ACE2 is located in endothelial cells throughout the cardiovascular system contributing to significant vascular dysfunction [3]. Indeed, vascular function, as measured by flow-mediated dilation (FMD) has been shown to be impaired in otherwise healthy young COVID-19 survivors just 3-4 weeks after infection [4] and persists for at least 6 months in patients who were hospitalized [5]. Recent work has shown a significant correlation between low plasma taurine levels (a naturally occurring amino acid which can help regulate cardiovascular and inflammation) and Long COVID symptoms, and the recovery of taurine levels was associated with fewer adverse events [6]. Notably, twelve weeks of taurine supplementation has been shown to improve blood pressure and vascular function in pre-hypertension [7]. These improvements could, in turn, improve orthostatic tolerance (i.e. lightheadedness while upright, a common symptom in Long COVID). Thus, the purpose of the current proposal is to compare Long COVID patients who are or who are not taking 12-wks taurine supplementation, measuring vascular and orthostatic responses. We hypothesize that those Long COVID patients taking taurine will have better vascular function and orthostatic responses.

Participants: Drawing on the results of Sun et al. (2016) [7] to calculate a sample size, we used an expected change in FMD of 3.2±4.7% with taurine supplementation, resulting in a sample size of 19. To account for potential participant drop-out, we intend to recruit 30 Long COVID patients aged 18-65, including 15 males and 15 females. As this is a pilot project, we will re-evaluate our sample sizes/statistical power when approximately 8 males and 8 females have been completed [8]. Duration and type of symptoms will be recorded using the Symptom Burden Questionnaire for Long COVID. Autonomic function will be assessed with the COMPASS-31 questionnaire and people with symptoms of orthostatic intolerance and/or vasomotor impairment will be recruited. Sex and gender will be self-identified and used as covariates. Any co-morbidities and medication use will be recorded but not excluded.

Study Design: This will be an observational study where half of the participants will already be taking taurine supplements and the other half will not. Each lab assessment will take approximately 60 minutes. Participants will come to York University at baseline and after 12 weeks of time has passed. During the first visit, they will be loaned a Polar heart rate monitor and instructed in its use for home data collection.

  1. Vascular function: Resting brachial artery FMD will be measured with Duplex ultrasound imaging according to international guidelines [9]. Briefly, five minutes of forearm vascular occlusion using a blood pressure cuff will be applied while brachial artery diameter and flow are measured before, during and for 3 minutes after cuff occlusion. Peak hyperemic brachial arterial velocity will also be measured using Doppler ultrasound immediately after cuff release. Analysis of FMD will be done with edge-detection software (Quipu) to expedite the analysis and reduce measurement error [10]. Concurrently an EndoPAT device will also be used to measure endothelial function.
  2. Orthostatic responses (during supine rest and 5-min 70o head-up tilt): Cardiovascular and respiratory measures: Heart rate will be measured by ECG, blood pressure/cardiac output will be monitored using a beat-by-beat non-invasive blood pressure device (NexFin), brain blood flow will be assessed with transcranial Doppler ultrasound, and respiratory rate will be assessed using a Respitrace. Heart Rate Variability (HRV): HRV provides an indicator of the autonomic control of heart rate (i.e. parasympathetic and sympathetic balance [11]) and will be analyzed using LabChart Pro 8.0 software in the supine and upright postures. Resting HRV will also be assessed using a Polar heart rate device at home, weekly. The heart rate data will be emailed to the students for analysis.

Analysis plan: Each variable described above will be measured before and after the 12-wks time period. To test the study hypotheses, repeated measures analysis of variance will be used to examine differences over time (SPSS). Sex, gender, and symptom duration will be covariates.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

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

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Heather Edgell, PhD
  • Phone Number: 22927 14167362100
  • Email: edgell@yorku.ca

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, M3J1P3
        • Recruiting
        • York University
        • Contact:

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Men and women aged 18-65 will be recruited who have been diagnosed by a medical professional with Long COVID, which is defined as persistent symptoms for >3 months after a COVID infection. Participants will also need to experience orthostatic intolerance, which is the feeling of dizziness or faintness when standing for a prolonged period. Participants must be able to transport themselves to York University and undergo testing which will take approximately 90 minutes. This includes the ability to undergo a tilt table test for 5 minutes. Therefore, any musculoskeletal problems which prevent upright posture will be excluded. Participants must be able to communicate in English and have the ability to be contacted by email or phone throughout the 12-week period. Current smokers will be excluded. Participants who regularly consume energy drinks that contain taurine (more than once per week) will be excluded.

Description

Inclusion Criteria:

  • Participants will have had symptoms of Long COVID post-infection for at least 3 months

Exclusion Criteria:

  • Inability to undergo tilt table testing for 5 minutes
  • Inability to transport selves to York University from their homes
  • Inability to speak English, or provide a translator
  • Blood clotting disorders

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

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Taurine supplementation
Long COVID patients will self-administer 12-wks of taurine supplementation
Dietary supplement: Taurine supplementation
Participants will self-administer 12-wks taurine supplementation
Time control
Long COVID patients who are not taking taurine supplementation

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Orthostatic responses
Time Frame: Baseline and 12-weeks
Measure cardiovascular and cerebrovascular responses to upright tilt using beat to beat blood pressure, ECG, and transcranial Doppler.
Baseline and 12-weeks
Vascular function
Time Frame: Baseline and 12-weeks
Flow-mediated dilation and EndoPAT response. These techniques concurrently measure endothelial function using the same protocol.
Baseline and 12-weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Heart rate variability
Time Frame: Over the course of 12 weeks
Variability of resting heart rate will be measured in lab using ECG and at home using a polar heart rate strap.
Over the course of 12 weeks

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
York University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Canadian Institutes of Health Research (CIHR)

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 30, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 17, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 30, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 31, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 5, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 3, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Edgell Long COVID trial

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

It is against REB protocol to provide individual data, particularly in small sample size studies.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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.

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