L-cysteine is a conditionally essential amino acid, one of onlythree sulfur-containing amino acids, the others being taurine (whichcan be produced from L-cysteine) and L-methionine from which L-cysteinecan be produced in the body by a multi-step process. Cysteine playsa role in the sulfation cycle, acting as a sulfur donor in phase IIdetoxification and as a methyl donor in the conversion of homocysteineto methionine. Cysteine also helps synthesize glutathione, one of thebodys most important natural detoxifiers. N-acetyl-cysteineis the acetylated form of L-cysteine, which is more efficiently absorbedand used.54-64

Glutathione (gamma-L-glutamyl-L-cysteinyl-glycine) is a peptide(short protein)-like molecule synthesized in the body from thethree amino acids L-glutamic acid, L-cysteine, and glycine. Glutathioneis one of the bodys most important and powerful antioxidants,helping to detoxify xenobiotics. A major function of vitamin Cis to keep glutathione in its reduced form so that they can continueto provide free radical quenching effects.65-68

Even though many published studies show that garlic, selenium,alpha-lipoic acid, L-cysteine, and N-acetyl-cysteine can boostcellular glutathione levels, people with health problems may benefitfrom taking high doses 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 toprevent these amino acids from being oxidized in the body.*