Summary
| Direction in Long COVID | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Metabolic |
| Also described as | Methylglycine |
| Compared against | HC, R (healthy controls, recovered individuals without persistent symptoms) |
| Associated symptoms | Depression, anxiety, brain fog |
| Test type | Blood test (serum / plasma / whole blood) |
| Source | Saito et al. 2024 — doi:10.3389/fimmu.2024.1341843 |
| Condition atlas | Long COVID Biomarker Atlas |
Other conditions where Sarcosine is reported
- Sarcosine in ME/CFS — ↓ reduced vs HC — LC overlap
See the cross-condition hub: Sarcosine across conditions.
Trials, interventions and tests
Also sold as a nutrient or supplement
Sarcosine (amino acid). Amino acid supplement. This tag means the analyte is also available orally; it is not a product endorsement and a low or high level does not by itself justify supplementation.
Related Metabolic markers in Long COVID
- Serine ↓
- Aspartate ↓
- ATP (plasma) ↓
- Asparagine ↓
- Glutamine ↓
- Arginine ↓
- Histidine ↓
- TCA cycle intermediates ↑
Full list: Long COVID Biomarker Atlas.
Frequently asked questions
Is Sarcosine high or low in Long COVID?
Reduced. Studies summarised in the OSMF atlas report lower Sarcosine in Long COVID than in healthy controls, recovered individuals without persistent symptoms. Source: Saito et al. 2024.
What symptoms is Sarcosine associated with in Long COVID?
The cited literature associates this marker with Depression, anxiety, brain fog. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Sarcosine?
It is measured as a blood test (serum / plasma / whole blood). Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal Sarcosine result diagnostic of Long COVID?
No. No single biomarker is diagnostic of Long COVID. Sarcosine findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is Sarcosine specific to Long COVID?
No. The same marker is also reported in ME/CFS in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
Cite this page
Subscribe on Substack
Last reviewed: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.