A quiet analytical research laboratory at night, racks of glass vials along a dim bench.

Antioxidant Defense and Liver Support: Glutathione and Its Precursors

The liver's main intracellular antioxidant is glutathione, and it is hard to deliver directly. Oral glutathione is largely broken down before absorption, and its precursor NAC has an oral bioavailability of roughly 6 to 10%. Vegalab's pipeline programs (NAC Nano and Glutathione Nano) address stability and uptake of these two molecules.

How the system works

Glutathione is a tripeptide (glutamate, cysteine, glycine) present at millimolar levels in liver cells. It neutralizes reactive oxygen species, regenerates vitamins C and E, and conjugates electrophilic metabolites for excretion. Synthesis is limited by cysteine supply, which is why N-acetylcysteine (NAC) is used as a precursor. Upstream, the Nrf2 pathway regulates glutathione synthesis enzymes. When a toxic load such as an acetaminophen overdose depletes hepatic glutathione, reactive metabolites bind liver proteins; NAC is the approved antidote for that specific situation.

Regulatory status by compound

Intravenous NAC (Acetadote) is FDA approved for acetaminophen overdose, and inhaled NAC is approved as a mucolytic. In the US, FDA issued guidance in 2022 stating it would exercise enforcement discretion for NAC sold as a dietary supplement. Glutathione is sold as a supplement ingredient in the US and several other markets. Silymarin (milk thistle) is a supplement or traditional herbal ingredient. None of these ingredients may carry a claim to treat or prevent liver disease outside an approved drug label.

The delivery problem

Glutathione is hydrolyzed by gamma-glutamyltransferase in the gut, and a single 3 g oral dose did not raise plasma glutathione in healthy volunteers. Longer daily dosing raised body stores in one six-month trial, so the evidence is mixed. NAC absorbs but undergoes extensive first-pass metabolism, and its sulfur odor complicates liquid formats. Both molecules oxidize readily: glutathione to its disulfide GSSG, NAC to its dimer. Stability on shelf is as much a problem as absorption.

Key facts

IV acetylcysteine (Acetadote) is FDA approved to prevent or lessen hepatic injury after acetaminophen overdose (FDA label, Acetadote 2004)
Oral bioavailability of NAC in humans was about 4% for reduced NAC and 9% for total NAC (Olsson et al. 1988, Eur J Clin Pharmacol 34:77)
A single 3 g oral dose of glutathione did not increase plasma glutathione in healthy volunteers (Witschi et al. 1992, Eur J Clin Pharmacol 43:667)
Daily oral glutathione for 6 months increased glutathione stores in blood and buccal cells (Richie et al. 2015, Eur J Nutr 54:251)
FDA stated it will exercise enforcement discretion for certain NAC products labeled as dietary supplements (FDA guidance, Policy Regarding N-acetyl-L-cysteine, 2022)

How our delivery technology applies

Both molecules carry a free thiol that oxidizes on contact with air and water. A multi-layer biopolymer shell reduces oxygen and moisture exposure during storage, and an outer layer designed to resist low pH can shift release past the stomach. For glutathione, the target is reducing enzymatic hydrolysis at the brush border; this is a research hypothesis measured by stability assays and pharmacokinetic studies, not an established outcome.

Discuss NAC Nano or Glutathione Nano partnership terms with our team.