NAC is the affordable precursor your body turns into glutathione; oral glutathione is the finished product but is poorly absorbed unless liposomal. For most people NAC (or glycine + NAC) is the better-evidenced route.
Side by side
| Feature | NAC | Glutathione |
|---|---|---|
| What it is | N-acetylcysteine — a cysteine source for making glutathione | The antioxidant itself (tripeptide) |
| Oral absorption | Good | Poor for standard forms; liposomal and S-acetyl forms do better |
| Evidence | Decades of clinical use; lungs, liver, mood adjunct | Growing; best data for liposomal forms |
| Typical amount | 600–1,200 mg/day | 250–500 mg/day (liposomal) |
| Taste/tolerance | Sulfur smell; can cause nausea on an empty stomach | Neutral |
| Cost | Low | High |
The evidence
Glutathione is the body's master antioxidant, but you make it from cysteine, glycine and glutamate — and cysteine is usually the limiting amino acid, which is what NAC supplies. The GlyNAC trials pair NAC with glycine and show improvements in oxidative stress and mitochondrial markers in older adults. Oral glutathione raises body stores only in trials using liposomal or high-dose forms.
Who each may suit
- You want the best-evidenced, affordable option
- Liver or lung support is the goal
- You'll pair it with glycine
- You don't tolerate NAC
- You'll use a liposomal form
- A clinician has recommended it (IV in some settings)
Cautions
NAC can thin mucus and, rarely, interact with nitroglycerin; stop before surgery. Neither is a substitute for treating the cause of oxidative stress (sleep, alcohol, blood sugar).
Cost
NAC is a fraction of the price of liposomal glutathione. GlyNAC (glycine + NAC) is the value protocol with the most interesting recent data.
Educational, not medical advice. Reviewed by the medical advisory board; last reviewed Sep 2026. Standards
