L-Cysteine is a crystalline free-form amino acid that is active in many body processes. L-Cysteine works in the liver to protect the body from harmful substances and may help to prevent oxidation of tissues. L-Cysteine, along with L-Glutamic acid and glycine, is the rate-limiting precursor in the synthesis of glutathione peroxidase, one of the body's main antioxidant enzymes, which minimizes lipid peroxidation (fats turning rancid).
L-Cysteine is a conditionally essential amino acid, meaning that it may be manufactured in our bodies if all conditions are met. This process is extremely complex however, requiring the availability of other amino acids and vitamins and is carried out through a number of enzymatic steps. Because of the complexity of this process there is a greater risk of deficiency for cysteine than for many other amino acids. L-Cysteine is a sulfur containing amino acid which can usually be made from L-Methionine and elemental sulfur by the body.
Because of its high affinity for binding metals and other toxins L-Cysteine is frequently taken in combination with Vitamin C to detoxify, chelate, and remove harmful metals and free radicals from the body. An adequate supply of Vitamin C and B6 should always accompany any L-Cysteine supplementation. One of the most important recent discoveries about cysteine is that is required for the formation of glutathione, a tripeptide that also contains the amino acids glycine and glutamic acid.
The cysteine-glutathione connection is important because glutathione is a critical regulator of cell health. It is essential for maintaining electrochemical balance in many cells. It functions as a detoxifying agent in the kidneys and is required for elimination of many environmental toxins, including fungicides, herbicides, nitrosamines, dyes, solvents, plastics, detergents, and insecticides. Glutathione is also required genetically, for synthesis and repair of DNA, as well as for neutralization of free radicals that can damage healthy cells. Immune function, nerve function and cell signaling functions are also heavily influenced by glutathione. Within the immune function category, wound healing, especially healing from skin wounds, appears to depend on glutathione availability.
What is the difference between Cysteine and Cystine? Cysteine is a monomer and Cystine is a dimmer, which is formed by two cysteine molecules. Generally, Cystine is more stable than Cysteine, however, both can be converted into the other form as required by the body. Most supplements contain Cysteine more than Cystine because the absorption of Cysteine is better than Cystine. Cysteine is required by the skin and detoxification of the body, and Cystine is required for vitamin B6 utilization and also helps for wound healing.