Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.
Well below target. Risk of deficiency symptoms tied to glutathione · liver.
Below the recommended daily target. Long-term adequacy not assured.
Daily target met. Standard nutritional support for glutathione · liver.
Common for specific health goals. Check the evidence for your situation before sustaining this level.
Past the point where extra intake typically helps. Evidence for further benefit is thin.
N-acetylcysteine — acetylated derivative of the conditionally essential amino acid cysteine. Used clinically as acetaminophen overdose antidote (>50 years), mucolytic, and increasingly studied for psychiatric, pulmonary, and longevity applications via its role as a glutathione precursor.
Hydrolysed to L-cysteine, which combines with glutamate and glycine via gamma-glutamylcysteine synthetase (the rate-limiting enzyme) and GSH synthase to produce reduced glutathione. GSH then donates electrons to oxidised substrates and to detoxify xenobiotics. The acetyl group makes NAC more stable and better-absorbed than free L-cysteine.
Not an essential nutrient — cysteine is the relevant precursor and is met by adequate dietary methionine/cysteine intake. Glutathione status may be marginal in chronic illness and aging.
Well-tolerated up to ~6 g/day orally; higher IV doses used in overdose. Sulfur metabolites can produce odour and mild GI upset.
N-acetyl-cysteine (NAC) at 600–1,200 mg/day in divided doses. Take on an empty stomach for absorption. Sulfur smell is normal. Don't combine with nitroglycerin without medical supervision. FDA contested NAC's dietary-supplement status briefly (2020-2022) but enforcement discretion has returned to allowing OTC sale.
Oral bioavailability of intact NAC is low (~10%) due to first-pass metabolism, but conversion to cysteine and incorporation into GSH is reliable. Empty stomach improves uptake. Plasma cysteine peaks at 1–2 h.
Glutathione status declines with age. GlyNAC (glycine + NAC, 1.3 g + 1 g of each per day in trials) restored GSH levels and improved mitochondrial function, insulin sensitivity, and inflammatory markers in older adults. Mechanism is well-grounded; outcome trials are early but promising.
N-acetyl-cysteine; glutathione precursor, antioxidant, mucolytic. Common dose 600–1200 mg.
The mechanisms and systems this nutrient feeds. Click any to drill into what runs on it.
★ = load-bearing / primary cofactor. Track these in My Journey.