Origin & tradition
Not traditional: NAC is derived from the amino acid L-cysteine and was developed as a pharmaceutical in the 1960s.
Western tradition · Antioxidant
NAC (N-Acetylcysteine)
The gold-standard glutathione precursor — a medical-grade antioxidant now recognized as key to correcting age-related glutathione depletion.
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Why longevity buyers care
Key active: N-acetylcysteine — glutathione precursor.
NAC replenishes cysteine, the rate-limiting substrate for glutathione synthesis. Glutathione declines ~50% by age 65. The GlyNAC protocol (glycine + NAC, 2021 Baylor RCT) corrected glutathione deficiency alongside mitochondrial dysfunction, insulin resistance, and oxidative stress in older adults. NAC is FDA-approved for acetaminophen overdose and mucolytic use.
Effect summary
Studied health outcomes
Editorial summary — This table is curated by hand from published research consensus, not automatically calculated from our trial database. Grades reflect our interpretation of the literature. Treat as a starting point, not a definitive verdict. See the Evidence panel below for the underlying trial and paper counts sourced directly from ClinicalTrials.gov and PubMed.
| Health outcome | Effect | Magnitude | Grade |
|---|---|---|---|
| Glutathione levels | Increases | Strong | A |
| Acetaminophen liver toxicity (emergency) | Decreases | Strong | A |
| Respiratory mucus / COPD symptoms | Decreases | Moderate | B |
| OCD / compulsive symptoms | Decreases | Moderate | B |
| Insulin resistance | Decreases | Minor | C |
| Oxidative stress markers | Decreases | Moderate | B |
Grade: A = robust RCTs · B = several RCTs / meta-analysis · C = limited or mixed RCTs · D = observational or early data
Dosage guidance
How NAC (N-Acetylcysteine) is typically used
- Typical dose
- 600–1,800 mg/day
- Form
- capsule or effervescent tablet
- Timing
- with or without food; split into 2–3 doses
NAC is the most clinically validated glutathione precursor. At 600mg 3×/day it's hospital-used for acetaminophen overdose. Also used for respiratory conditions (mucolytic) and OCD/compulsive symptoms. GlyNAC combines NAC with glycine for synergistic glutathione effect.
Informational only — not a prescription or personalised medical advice. Consult a qualified clinician before starting any supplement or medication.
Evidence summary
What the research actually says
80Evidence confidence
Extensive human-trial evidence933 randomized controlled trials · 377 meta-analyses / systematic reviews
Medical-grade compound; GlyNAC RCT in older adults; aging-specific trials ongoing
NAC replenishes cysteine, the rate-limiting substrate for glutathione synthesis. Glutathione declines ~50% by age 65. The GlyNAC protocol (glycine + NAC, 2021 Baylor RCT) corrected glutathione deficiency alongside mitochondrial dysfunction, insulin resistance, and oxidative stress in older adults. NAC is FDA-approved for acetaminophen overdose and mucolytic use.
1registered clinical trials reference this intervention
3selected from 6+ PubMed papers (longevity / aging angle)
- The glutathione precursor N-acetylcysteine improves immune function in postmenopausal women
- N-Acetylcysteine extends lifespan of Drosophila via modulating ROS scavenger gene expression
- Pharmacological recapitulation of the lean phenotype induced by the lifespan-extending sulfur amino acid-restricted diet
Key active: N-acetylcysteine — glutathione precursor.
According to PubMed and ClinicalTrials.gov: trial counts from ClinicalTrials.gov, peer-reviewed literature from PubMed. Counts auto-refresh weekly; last checked 2026-06-12. They include trials across many endpoints, not only longevity.
Informational only — not medical advice, a treatment claim, or a substitute for a qualified clinician. Evidence strength varies; we show mixed and null results on purpose.
Evidence collections
NAC (N-Acetylcysteine) appears in
Compare the evidence
How NAC (N-Acetylcysteine) stacks up
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