An observational study in Long COVID Syndrome, sponsored by York University. Recruiting at 1 site in Canada. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-06-05.
Sponsored by York University · Observational
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).
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.
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.
604 studies on the registry are indexed under Post-Acute COVID-19 Syndrome; 201 are open to participants now.
This study's planned enrollment of 30 is below the median of 150 across 173 observational studies indexed under Post-Acute COVID-19 Syndrome.
Browse Post-Acute COVID-19 Syndrome studies →York University is the lead sponsor of 51 studies on the registry; 12 are open to participants now.
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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.
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Exclusion Criteria:
Long COVID patients will self-administer 12-wks of taurine supplementation
Dietary Supplement: Taurine supplementation
Long COVID patients who are not taking taurine supplementation
Participants will self-administer 12-wks taurine supplementation
Orthostatic responses
Measure cardiovascular and cerebrovascular responses to upright tilt using beat to beat blood pressure, ECG, and transcranial Doppler.
Time frame: Baseline and 12-weeks
Vascular function
Flow-mediated dilation and EndoPAT response. These techniques concurrently measure endothelial function using the same protocol.
Time frame: Baseline and 12-weeks
Heart rate variability
Variability of resting heart rate will be measured in lab using ECG and at home using a polar heart rate strap.
Time frame: Over the course of 12 weeks
Plan to share: No — It is against REB protocol to provide individual data, particularly in small sample size studies.
Started Jun 2026 (actual). Primary completion is estimated for Jun 2027, 12 months after the start.
Of 98 non-industry observational studies under Post-Acute COVID-19 Syndrome, half reached primary completion within 27 months of starting (the median), counting those still running; a quarter within 17 and three quarters within 39. This study's planned 12 months is below that.
Counting every sponsor, half of 105 studies reached it within 27 months; a quarter within 14 and three quarters within 39.
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