N-Acetylcysteine (NAC)

Evidence: ★★★★☆ · Status: OTC Supplement, Prescription

In plain English

Your cells' main antioxidant (glutathione) needs a specific building block that runs low. NAC delivers it, restocking your internal rust-protection — especially for the liver.

How it works

Precursor to cysteine, the rate-limiting amino acid for glutathione (GSH) — the body's master antioxidant. Replenishes GSH, modulates glutamate in the brain (obsessive/compulsive circuits), and thins mucus. FDA-approved as the antidote for paracetamol overdose.

Molecular target & official sources

GCLC glutamate-cysteine ligase (NCBI Gene) · Acetylcysteine (PubChem CID 12035)

Protocol

600–1,200 mg/day. Longevity: pair with glycine ("GlyNAC").

Bottom line

Cheap, versatile, genuinely useful for liver and antioxidant capacity.

Helps with: Live Longer · Stress & Anxiety

The human evidence

Gold-standard, hospital-proven as the antidote for paracetamol (acetaminophen) overdose. Beyond that, moderate evidence for mucus/COPD and emerging psychiatric use (OCD, trichotillomania, addiction) as a glutathione/glutamate modulator.

Stacks with

Glycine — together as GlyNAC they restore glutathione more than either alone.

Shares a pathway — often paired with: L-Theanine, Magnesium, Phentermine / Qsymia (phentermine-topiramate), Ashwagandha (Withania somnifera).

Avoid combining with

High doses taken right around training can blunt some of the adaptive benefit of exercise (it is an antioxidant). Caution alongside nitroglycerin.

Availability & where to buy

Prescription only. Prescription-only — a doctor must prescribe it. Not sold over the counter. (In Singapore: HSA-regulated.) Cheap — ~S$20–35 for a few months.

How it works: the GABA / Glutamate pathway →

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