L-cysteine is a conditionally essential amino acid, one of only three sulfur-containingamino acids, the others being taurine (which can be produced from L-cysteine)and L-methionine from which L-cysteine can be produced in the body by a multi-stepprocess. Cysteine plays a role inthe sulfation cycle, acting as a sulfur donor in phase II detoxificationand as a methyl donor in the conversion of homocysteine to methionine.Cysteine also helps synthesize glutathione, one of the bodys mostimportant natural detoxifiers. N-acetyl-cysteine is the acetylatedform ofL-cysteine, which is more efficiently absorbed and used.54-64

Glutathione (gamma-L-glutamyl-L-cysteinyl-glycine) is a peptide (short protein)-likemolecule synthesized in the body from the three amino acids L-glutamicacid, L-cysteine, and glycine. Glutathione is one of the bodys most importantand powerful antioxidants, helping to detoxify xenobiotics. A major functionof vitamin C is to keep glutathione in its reduced form so that they cancontinue to provide free radical quenching effects.65-68

Even though many published studies show that garlic, selenium, alpha-lipoicacid, L-cysteine, and N-acetyl-cysteine can boost cellular glutathionelevels, people with health problems may benefit from taking highdoses of glutathione.65,69-71*

When taking L-cysteine, N-acetyl-cysteine, or glutathione, it is recommendedthat three times as much vitamin C should be taken at the same time to preventthese amino acids from being oxidized in the body.*