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

December 31, 2025 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-week taurine supplementation, on vascular function and the cardio/cerebrovascular responses to upright posture in LC. We will measure resting vascular function with EndoPAT and ultrasound, resting heart rate variability, and the blood pressure, heart rate, and brain blood flow response to 5 minutes of head-up tilt before and after 12-weeks of taurine supplementation in LC.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

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 investigate the efficacy of 12-wks taurine supplementation on vascular and orthostatic responses in Long COVID. We hypothesize that Long COVID patients will improve their vascular function and orthostatic response after 12-wks of taurine supplementation.

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 interventional open-label single group assignment study. Each lab assessment will take approximately 60 minutes. Participants will come to York University before and after 12-wks taurine supplementation (2 x 675mg twice daily). During the first visit, they will be given the supplements and 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 taurine supplementation. 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

Interventional

Enrollment (Estimated)

30

Phase

  • 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

  • Name: Heather Edgell, PhD
  • Phone Number: 22927 14167362100
  • Email: edgell@yorku.ca

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, M3J1P3
        • York University

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

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

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Taurine supplementation
Participants will take 12-wks of taurine supplementation (2 x 675mg twice daily).
Dietary supplement: Taurine supplementation
Participants will take 12-wks taurine supplementation (2 x 675mg twice daily).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Orthostatic responses
Time Frame: Baseline and 12-week dietary supplementation.
Measure cardiovascular and cerebrovascular responses to upright tilt using beat to beat blood pressure, ECG, and transcranial Doppler.
Baseline and 12-week dietary supplementation.
Vascular function
Time Frame: Baseline and 12-week dietary supplementation.
Flow-mediated dilation and EndoPAT response. These techniques concurrently measure endothelial function using the same protocol.
Baseline and 12-week dietary supplementation.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Heart rate variability
Time Frame: Baseline and 12-week dietary supplementation.
Variability of resting heart rate will be measured in lab using ECG and at home using a polar heart rate strap.
Baseline and 12-week dietary supplementation.

Collaborators and Investigators

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

Sponsor

York University

Collaborators

Canadian Institutes of Health Research (CIHR)
Long COVID Web

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 (Estimated)

April 1, 2026

Primary Completion (Estimated)

December 31, 2026

Study Completion (Estimated)

March 31, 2027

Study Registration Dates

First Submitted

December 17, 2025

First Submitted That Met QC Criteria

December 30, 2025

First Posted (Estimated)

December 31, 2025

Study Record Updates

Last Update Posted (Actual)

January 6, 2026

Last Update Submitted That Met QC Criteria

December 31, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID 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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