Glutathione Supplement

## What is glutathione? Glutathione (GSH) is a small tripeptide synthesized in every cell from three amino acids: glutamate, cysteine, and glycine. It is the body's most abundant intracellular antioxidant, present at 1 to 10 millimolar concentrations in most tissues, with the highest levels in liver. Its central biological roles include neutralizing reactive oxygen species, recycling oxidized vitamins C and E back to their active forms, conjugating xenobiotics for excretion via the GSH-S-transferase enzyme system, and regulating the redox state of cysteine residues on proteins (the central mechanism of cellular redox signaling). Glutathione exists in reduced (GSH) and oxidized (GSSG) forms, with the GSH:GSSG ratio serving as the standard cellular redox indicator. Healthy cells maintain a ratio of 100:1 or higher; chronic disease states (HIV, cancer, neurodegenerative disease) often show ratios below 10:1. Supplementation has been studied for decades with mixed results. Oral glutathione is largely degraded in the gut to its constituent amino acids before absorption. The 2014 Richie trial (n=54, 250 to 1,000 mg/day for 6 months) reported significant increases in body GSH stores, partially overturning the older consensus that oral GSH was inactive. Sublingual, liposomal, and IV forms bypass the gut and produce more reliable plasma rises. NAC (N-acetylcysteine) is often a better indirect strategy because cysteine is the rate-limiting precursor for GSH synthesis. Legal status: dietary supplement in the US, EU, and most major markets. Not WADA-listed. ## Mechanism of action Glutathione is the substrate for several enzyme systems: - **Glutathione peroxidase**: reduces hydrogen peroxide and lipid peroxides using GSH as the electron donor; central to oxidative stress defense - **Glutathione S-transferase**: conjugates electrophilic toxins (drugs, heavy metals, environmental toxins) to GSH for biliary or renal excretion - **Glutathione reductase**: regenerates GSH from oxidized GSSG using NADPH - **Glutaredoxin**: catalyzes GSH-dependent thiol-disulfide exchange on proteins, regulating redox-sensitive signaling The rate-limiting step in GSH synthesis is the gamma-glutamylcysteine ligase (GCL) enzyme, which combines glutamate and cysteine. Cysteine availability is the practical bottleneck, which is why NAC (an N-acetylated form of cysteine that bypasses the gut conversion) is the most-used indirect GSH-raising supplement. ## Evidence base by outcome ### Liver function B-tier. NAFLD trials report modest improvements in liver enzymes with oral GSH at 300 to 1,000 mg/day; the 2017 Honda trial (n=29, 300 mg/day for 4 months) reported reduced ALT in NAFLD patients. ### Heavy metal detoxification C-tier. IV glutathione is used clinically for acetaminophen overdose (NAC works through GSH replenishment). Heavy-metal chelation claims for oral GSH are weak. ### Aging skin and oxidative stress C-tier. Small trials report improved skin elasticity and reduced wrinkles at 250 to 500 mg/day for 12 weeks. Effect sizes modest. ### Immune function C-tier. Low GSH correlates with poor immune function in HIV and aging cohorts; supplementation modestly improves immune markers but rarely changes hard outcomes. ### Cardiovascular outcomes D-tier. No completed RCT measures cardiovascular events on glutathione supplementation. ## Dosage and administration - **Oral reduced GSH**: 250 to 1,000 mg/day, divided. Bioavailability variable; the Richie 2014 protocol used 1,000 mg/day for 6 months. - **Liposomal GSH**: 200 to 500 mg/day. Better bioavailability than capsule form. - **Sublingual GSH**: 100 to 300 mg, hold under tongue 1 to 2 minutes. Bypasses gut conversion. - **IV glutathione**: 600 to 2,400 mg, weekly. Clinical setting; not for self-administration. - **Indirect via NAC**: 600 to 1,800 mg/day NAC; rate-limiting precursor strategy. Morning empty-stomach dosing is conventional for oral forms; with-meal dosing for liposomal forms. No cycling required. Tolerance does not develop. ## Side effects and safety Clean safety record at supplemental doses. Mild GI upset is the main reported issue. IV administration carries injection-site risks and rare hypersensitivity. Asthma patients should approach IV / inhaled GSH with caution; bronchospasm has been reported. Drug interactions are minimal. Theoretical concern with chemotherapy (some agents rely on GSH depletion in tumor cells); consult oncologist. ## Stack interactions and timing NAC is the most common pairing; NAC raises cysteine, the GSH precursor. Pair safely. Vitamin C and selenium support GSH function (vitamin C recycles GSSG to GSH; selenium is a cofactor for glutathione peroxidase). Pair safely. Milk thistle and TUDCA pair through different liver-protective mechanisms. Pair safely. ## Practical notes Quality varies. Setria glutathione is the most-studied branded form (used in Richie 2014). Liposomal forms vary in actual encapsulation efficiency. For most users seeking GSH support: NAC at 600 to 1,200 mg/day is more cost-effective than direct glutathione supplementation. Direct GSH is the right pick when NAC is contraindicated or insufficient. Expect skin and energy effects in 4 to 12 weeks if any. Liver enzyme changes (if applicable) in 8 to 16 weeks.