Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| NAC (N-Acetyl Cysteine) | Sulforaphane (Broccoli Seed Extract) | |
|---|---|---|
| Category | Supplements | Supplements |
| Standard Dose | 600-1200mg daily | 10-30mg sulforaphane daily (equivalent to ~100-200mg broccoli seed extract standardized to glucoraphanin + myrosinase) |
| Timing | On empty stomach for best absorption, 30 min before meals. Split doses if >600mg. | On empty stomach or with light meal. Myrosinase enzyme required for conversion from glucoraphanin — ensure supplement contains it or add mustard seed powder. |
| 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)
Sulforaphane is the most potent natural activator of the Nrf2-ARE (antioxidant response element) pathway. It modifies Keap1 cysteine residues, releasing Nrf2 to translocate to the nucleus and upregulate >200 cytoprotective genes including NQO1, glutathione S-transferases, heme oxygenase-1, and UDP-glucuronosyltransferases (Phase II detox enzymes). It also inhibits HDAC activity (epigenetic modification), induces Phase II/III xenobiotic metabolism, and suppresses NF-kB inflammatory signaling.
10-30mg sulforaphane daily (equivalent to ~100-200mg broccoli seed extract standardized to glucoraphanin + myrosinase)
On empty stomach or with light meal. Myrosinase enzyme required for conversion from glucoraphanin — ensure supplement contains it or add mustard seed powder.
ongoing
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