NAC (N-Acetyl Cysteine) vs Quercetin

Mechanism

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.

Standard Dosing

600-1200mg daily

Timing

On empty stomach for best absorption, 30 min before meals. Split doses if >600mg.

Cycle Duration

Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production)

Side Effects

• Nausea
• GI upset
• Sulfurous odor/taste
• Rare: skin rash
• Potential zinc/copper chelation at very high doses

Contraindications

• Active gastric ulcers (may increase gastric acid)
• Asthma (rare bronchospasm with inhaled form)
• Concurrent chemotherapy (discuss with oncologist)

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Mechanism

Quercetin is a flavonoid that inhibits mast cell degranulation and histamine release, functions as a potent senolytic (selectively clearing senescent cells) when combined with dasatinib or fisetin, and activates AMPK and SIRT1 pathways. It inhibits PI3K/Akt/mTOR signaling, suppresses NF-kB, and modulates JAK-STAT inflammatory cascades. As a zinc ionophore, it facilitates zinc entry into cells, which may inhibit viral RNA-dependent RNA polymerase.

Standard Dosing

500-1000mg daily

Timing

With meals for absorption. For senolytic effect: 3-day pulse monthly on empty stomach.

Cycle Duration

ongoing for general use; pulsed monthly for senolytic protocols

Side Effects

• Headache
• Mild GI upset
• Tingling extremities at high doses
• Rare: kidney toxicity at very high doses

Contraindications

• Pregnancy/lactation at high doses
• Concurrent cyclosporine therapy

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