N-acetylcysteine is an inexpensive oral supplement, a modified amino acid that supplies raw material for glutathione, the body’s main internal antioxidant. Human evidence is strongest for refilling depleted glutathione, preventing liver injury after acetaminophen overdose, and reducing flare-ups in long-standing airway disease. Claims tied to aging rest on a few small studies from one laboratory. It thins the blood and damps the signals that drive training adaptation. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Homocysteine | 6–8 µmol/L | Direct downstream target of the thiol effect |
| hs-CRP | Below 1.0 mg/L | Tracks the anti-inflammatory claim |
| GGT | 10–20 U/L (men), 8–15 U/L (women) | Best routine proxy for thiol and oxidative load |
| ALT and AST | 10–26 U/L | Confirms the compound is not stressing the liver |
| Serum zinc | 90–120 µg/dL | Detects binding-driven depletion |
| Serum copper | 80–120 µg/dL | Detects binding-driven depletion on the other side of the zinc–copper axis |
| eGFR | Above 90 mL/min/1.73 m² | Governs clearance and the avoidance threshold |
| TSH | 0.5–2.0 mIU/L | Screens for the iodide-contamination failure mode |
| Uric acid | 3.5–5.5 mg/dL | Cardiometabolic marker vulnerable to assay interference |
| Red-blood-cell glutathione, or the reduced-to-oxidized ratio | No established target range; the change from the individual’s own baseline is what to track | The variable the intervention most directly targets |
Cadence: Baseline before starting; 12 weeks to confirm the intended direction on homocysteine and inflammation; then every 6–12 months on continuous use. Trace minerals and TSH move forward to 6 months above 1,200 mg daily. Dosing pauses 48 hours before every draw.