Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| NAC (N-Acetyl Cysteine) | Selenium (Selenomethionine) | |
|---|---|---|
| Category | Supplements | Minerals |
| Standard Dose | 600-1200mg daily | 200 mcg selenomethionine daily |
| Timing | On empty stomach for best absorption, 30 min before meals. Split doses if >600mg. | With meals. Can be taken any time of day. |
| Cycle Duration | Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production) | ongoing |
| Evidence Level | strong_human | strong_human |
NAC is a precursor to L-cysteine, the rate-limiting substrate for glutathione (GSH) synthesis via glutamate-cysteine ligase. It directly replenishes intracellular GSH, the master endogenous antioxidant. NAC also modulates glutamatergic neurotransmission by stimulating the cystine-glutamate antiporter (system Xc-), influencing extrasynaptic glutamate levels. Additionally, it acts as a mucolytic by cleaving disulfide bonds in mucus glycoproteins.
600-1200mg daily
On empty stomach for best absorption, 30 min before meals. Split doses if >600mg.
Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production)
Selenium is incorporated as selenocysteine (the 21st amino acid) into 25 selenoproteins. Key enzymes: glutathione peroxidases (GPx1-4, reduce hydrogen peroxide and lipid hydroperoxides), thioredoxin reductases (TrxR1-3, maintain cellular redox balance), iodothyronine deiodinases (DIO1-3, convert T4 to T3 and regulate thyroid hormone metabolism), selenoprotein P (selenium transport and brain antioxidant), and selenoprotein W (muscle antioxidant). Selenium is essential for thyroid function, immune defense, reproductive health, and cancer chemoprevention.
200 mcg selenomethionine daily
With meals. Can be taken any time of day.
ongoing
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