Glutathione is a tripeptide — three amino acids bonded together: glycine, cysteine, and glutamic acid. Your body synthesises it in every cell, in the cytoplasm, from those three precursors. It is not a vitamin, not a mineral, not an essential nutrient in the traditional sense — it is a molecule your body builds and continuously recycles, the hub of your cellular antioxidant defence system, and the primary molecule through which the liver conjugates toxic compounds for excretion in Phase Two detoxification.
When it is depleted — through oxidative stress, heavy metal burden, chronic inflammation, poor nutrition, or the accumulated demands of chronic illness — the consequences are not limited to one system. They radiate outward through every system that depends on oxidative balance, detoxification capacity, and immune function. Which is, essentially, all of them.
What Glutathione Actually Does
Primary cellular antioxidant
Glutathione neutralises reactive oxygen species — the free radicals generated by normal metabolism, amplified by illness, toxins, and inflammation. In its reduced form (GSH), it donates an electron to neutralise the radical and becomes oxidised glutathione (GSSG). The glutathione reductase enzyme then regenerates GSH using NADPH. This cycling is continuous; the ratio of GSH to GSSG is a direct measure of cellular oxidative stress.
Phase Two liver detoxification
Glutathione conjugation is one of the six Phase Two detoxification pathways. The glutathione S-transferase enzymes attach glutathione to reactive compounds — particularly heavy metals, organic solvents, lipid peroxides, and reactive Phase One intermediates — creating water-soluble conjugates for excretion. Without adequate glutathione, Phase Two conjugation is incomplete and reactive intermediates accumulate.
Heavy metal chelation and transport
Glutathione is the primary cellular chelator of heavy metals. Mercury, lead, arsenic, and cadmium are bound by glutathione within cells and transported into the bile for faecal excretion. This mechanism is why heavy metal accumulation directly depletes glutathione — the metal burden consumes glutathione faster than it can be regenerated, eventually overwhelming the system.
Immune system regulation
Lymphocyte proliferation and natural killer cell function both require adequate intracellular glutathione. Oxidative stress from glutathione depletion suppresses immune function through multiple pathways. This is one of the mechanisms behind the immune compromise that accompanies chronic illness — the illness depletes glutathione, the depletion further compromises immunity, creating a cycle that worsens both.
Mitochondrial protection
Mitochondria have their own separate glutathione pool — mitochondrial glutathione (mGSH) — distinct from cytoplasmic glutathione. Mitochondria produce the highest concentration of reactive oxygen species in the cell. mGSH is their primary protection. When it is depleted, mitochondrial membrane integrity fails, oxidative phosphorylation efficiency drops, and cellular energy production declines. Mitochondrial dysfunction and glutathione depletion are tightly coupled.
DNA repair and synthesis
Glutathione is required by ribonucleotide reductase — the enzyme that converts RNA nucleotides to DNA nucleotides — making it essential for DNA synthesis and repair. Under oxidative stress, DNA damage accumulates faster than repair can occur, partly because the glutathione required for the repair enzyme is being consumed elsewhere by the oxidative assault.
The OAT Signal — Pyroglutamic Acid as the Depletion Marker
One of the most clinically significant findings on the Organic Acids Test is elevated pyroglutamic acid — also called pyroglutamate or 5-oxoproline. This marker is the most sensitive functional indicator of glutathione depletion available on routine testing, and understanding why requires a brief explanation of the gamma-glutamyl cycle.
The body synthesises glutathione through a two-step enzymatic process. The first step — catalysed by gamma-glutamylcysteine synthetase — combines glutamate and cysteine to form gamma-glutamylcysteine. The second step adds glycine to complete the tripeptide. This synthesis is feedback-inhibited by glutathione itself — when glutathione levels are adequate, the enzyme slows production.
When glutathione is depleted and demand is high, the first enzyme runs at maximum rate. Gamma-glutamylcysteine accumulates. If cysteine — the rate-limiting precursor — is insufficient to keep pace with demand, gamma-glutamylcysteine cyclises spontaneously to form pyroglutamate. It piles up. The OAT measures it in urine. Elevated pyroglutamate is the biochemical signature of a system trying to make glutathione faster than its precursor supply allows.
Elevated pyroglutamic acid on the OAT is not a diagnosis — it is a signal. It tells you that glutathione synthesis is running under demand and that cysteine supply is the bottleneck. The clinical question it raises is: what is consuming glutathione faster than it can be regenerated? Heavy metal burden, chronic inflammation, toxic chemical exposure, and severe oxidative stress from any cause are all candidates.
What Depletes Glutathione
How to Actually Restore Glutathione
Oral glutathione supplementation has a complicated history. Early research suggested poor bioavailability — glutathione is a tripeptide that digestive enzymes break into its component amino acids before absorption, meaning you were supplementing glycine, cysteine, and glutamic acid rather than glutathione itself. More recent research has complicated this picture, but the most reliable approach to raising intracellular glutathione remains supporting synthesis rather than attempting direct supplementation through standard oral routes.
N-Acetyl Cysteine (NAC)
The rate-limiting precursor to glutathione synthesis, in a stable, bioavailable form. Cysteine itself is poorly absorbed orally and oxidises rapidly. NAC bypasses these limitations. It is absorbed, converted to cysteine intracellularly, and directly feeds glutathione synthesis. Extensively researched, well-tolerated, the most evidence-supported method of raising intracellular glutathione. 600mg twice daily is a standard clinical starting point; up to 1800mg in divided doses in acute situations. The clinical antidote for paracetamol overdose — the highest-stakes glutathione repletion situation in medicine.
Glycine
The third amino acid of the glutathione tripeptide and frequently the second rate-limiting precursor after cysteine in older adults and those with poor dietary protein. Research from Eric Verdin’s group showed that NAC plus glycine — GlyNAC — raises glutathione more effectively than NAC alone, particularly in ageing-associated depletion where glycine availability declines. A simple, inexpensive addition to NAC supplementation with meaningful supporting evidence. 1-3g daily in divided doses alongside NAC.
Liposomal Glutathione
Encapsulating glutathione in phospholipid liposomes protects it from digestive degradation and facilitates direct cellular uptake through membrane fusion. Liposomal delivery has demonstrated significantly higher bioavailability than standard oral glutathione in published research. More expensive than NAC but appropriate when direct repletion is the clinical priority rather than supporting synthesis. Useful in people with compromised synthetic capacity from severe illness or ageing, and as an adjunct to chelation support.
Alpha Lipoic Acid (ALA)
A naturally occurring antioxidant that regenerates glutathione from its oxidised form (GSSG back to GSH) and also directly recycles vitamins C and E. ALA addresses the oxidised-to-reduced ratio — effective when the problem is insufficient regeneration rather than insufficient synthesis. Also chelates certain heavy metals including arsenic and mercury, making it a clinically relevant addition to heavy metal support protocols. 200-600mg daily; always take with food.
Reduced Glutathione (S-Acetyl)
S-acetylglutathione has an acetyl group protecting the cysteine thiol from oxidation in the digestive tract. It passes the intestinal lining more intact than standard reduced glutathione and is deacetylated intracellularly. Better evidence for bioavailability than standard oral GSH. A reasonable middle ground between liposomal and precursor-only approaches.
Sulphur-Rich Foods
Garlic, onions, leeks, cruciferous vegetables (broccoli, Brussels sprouts, cauliflower, kale), egg yolks, and red meat provide the sulphur amino acids that feed glutathione synthesis. Sulforaphane from broccoli and its sprouts is a particularly potent activator of Nrf2 — the transcription factor that upregulates the body’s own antioxidant and detoxification enzyme production, including glutathione synthetase. No supplement replaces the dietary substrate.
Testing Glutathione Status
Direct measurement of glutathione is possible through specific laboratory tests — whole blood glutathione (measuring total and reduced glutathione) or the GSH:GSSG ratio. These are not standard blood panel markers but are available through specialist functional labs.
More practically, the Organic Acids Test provides the pyroglutamic acid marker — the most clinically accessible functional indicator of glutathione synthesis under demand. Elevated pyroglutamate, in the context of heavy metal exposure history, chronic illness, or the clinical picture of oxidative overwhelm, is a reliable signal that glutathione support should be part of the clinical approach.
On blood chemistry, low albumin can reflect reduced hepatic glutathione synthesis capacity — albumin production and glutathione synthesis share overlapping precursor pathways. GGT elevation — gamma-glutamyl transferase — is another indirect marker: GGT is produced in response to oxidative stress as part of the gamma-glutamyl cycle, and its elevation, even within the laboratory normal range, warrants consideration of glutathione status alongside other liver stress markers.
Identify the cause of depletion first. Supplementing glutathione precursors while the source of oxidative drain remains in place is running a bath with the plug out. Heavy metal burden, H. pylori infection, gut dysbiosis driving chronic LPS translocation, ongoing chemical exposure — these upstream drivers need to be addressed alongside glutathione support, not sequentially.
Start with NAC. 600mg twice daily with meals. Add glycine (1-2g) for enhanced effect, particularly in older adults. This is the most evidence-supported, most cost-effective starting point.
Add liposomal or S-acetyl glutathione when the clinical priority is direct repletion — heavy metal chelation support, severe depletion from major illness, or inadequate response to precursor supplementation alone.
Add ALA when heavy metal burden is suspected — it regenerates glutathione from its oxidised form and provides direct chelation support. Not with high-dose DMSA chelation protocols without appropriate clinical supervision.
Retest. OAT pyroglutamate and GGT trend over three to four months are the most accessible markers for assessing response to glutathione support.
Glutathione is not a supplement in the conventional sense — not a nutrient that is absent from your diet that you add back. It is an endogenous defence molecule that your body produces continuously, recycles continuously, and depends on continuously. When it is depleted, the deficit is not a dietary insufficiency. It is a signal that the oxidative demand on the system exceeds its synthetic and regenerative capacity — and addressing it requires both supporting synthesis and reducing the demand. The first question is always: what is consuming it faster than it can be replenished?