Glutathione (GSH) is a tripeptide and is an antioxidant, protecting cells from free radicals. Glutathione is not an essential nutrient since it can be synthesized from the amino acids L-cysteine, L-glutamic acid, and glycine. While all cells in the human body are capable of synthesizing glutathione, liver glutathione synthesis has been shown to be essential.
Glutathione exists in reduced (GSH) and oxidized (GSSG) states. In the reduced state, it is able to donate a reducing equivalent (H++ e-) to other unstable molecules, such as reactive oxygen species. Glutathione (GSH) participates as a cofactor for the enzyme glutathione peroxidase. It is also important as a hydrophilic molecule that is added to lipophilic toxins and waste in the liver during biotransformation before they can become part of the bile. Glutathione is also needed for the detoxification of methylglyoxal, a toxin produced as a byproduct of metabolism.
An increased GSSG-to-GSH ratio is considered indicative of oxidative stress.
Glutathione taken orally is not well absorbed across the GI tract. However, tissue and serum glutathione concentrations can be raised by increased intake of the precursor cysteine, or in chronic conditions, by S-adenosylmethionine (SAMe). Glutathione precursors rich in cysteine include N-acetylcysteine (NAC), glutamine, glycine, vitamin C and undenatured whey protein and these supplements have been shown to increase glutathione content (all present in the Energy Revitalization System vitamin powder — for this reason).
An important advance? Key problems in supplementing with glutathione is that the supplements got digested and oxidized before they were absorbed, making them ineffective. A key advance has resulted in a form that gets absorbed and stays in the critical reduced form. This is called "Clinical Glutathione" by EuroPhrma. Dissolve 1 under the tongue 2x day for 3 months, then 1-2x day.