Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Milk Thistle (Silymarin) | NAC (N-Acetyl Cysteine) | |
|---|---|---|
| Category | Supplements | Supplements |
| Standard Dose | 200-400mg silymarin daily (standardized to 70-80% silymarin) | 600-1200mg daily |
| Timing | With meals. Split doses for higher amounts. Phytosome form can be taken without food. | On empty stomach for best absorption, 30 min before meals. Split doses if >600mg. |
| Cycle Duration | Cycle 8-12 weeks for liver support; ongoing at low dose for maintenance | Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production) |
| Evidence Level | strong_human | strong_human |
Silymarin is a complex of flavonolignans (silybin A, silybin B, silychristin, silydianin, isosilybin) with silybin being the most active. Hepatoprotective mechanisms: stabilizes hepatocyte cell membranes by altering outer lipid layer composition (preventing toxin penetration), stimulates ribosomal RNA polymerase I (accelerating hepatocyte protein synthesis and regeneration), inhibits NF-kB and TNF-alpha (anti-inflammatory), scavenges free radicals (both ROS and RNS), promotes glutathione synthesis (increases intracellular GSH by 35%), and inhibits hepatic stellate cell activation (anti-fibrotic). Silybin also activates AMPK and enhances bile flow.
200-400mg silymarin daily (standardized to 70-80% silymarin)
With meals. Split doses for higher amounts. Phytosome form can be taken without food.
Cycle 8-12 weeks for liver support; ongoing at low dose for maintenance
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)
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