:Glutathione & Cysteine:

Functions: Detoxifier and antioxidant.

Cysteine is important in energy metabolism. As cystine, it is a structural component of many tissues and hormones.

What makes L-cysteine and all the chemical variants of it that are used in modern medicine: N-acetylcysteine (NAC), D-penicillamine (di-methylcysteine), gamma glutamyl cystine, and cysteamine, so active pharmacologically is that cysteine is a precursor of the ubiquitous tripeptide glutathione.

Glutathione is a compound synthesized from cysteine, perhaps the most important member of the body's toxic waste disposal team.
Like cysteine, glutathione contains the crucial thiol (-SH) group that makes it an effective antioxidant. There are virtually no living organisms on this planet-animal or plant whose cells don't contain some glutathione. Scientists have speculated that glutathione was essential to the very development of life on earth.

Glutathione has many roles; in none does it act alone. It is a coenzyme in various enzymatic reactions. The most important of these are redox reactions, in which the thiol grouping on the cysteine portion of cell membranes protects against peroxidation; and conjugation reactions, in which glutathione (especially in the liver) binds with toxic chemicals in order to detoxify them. Glutathione is also important in red and white blood cell formation and throughout the immune system. (See Selenium also)

Through these basic functions, glutathione is important Everyone is likely to be exposed to many of the pollutants GSH detoxifies, including lead, mercury, radiation, pesticides herbicides, fungicides, plastics, nitrates, cigarette smoke, birth control pills and other drugs. At the same time, cysteine, by its rapid conversion to GSH, protects against these toxins.

Glutathione's clinical uses include the prevention of oxygen toxicity in hyperbaric oxygen therapy, treatment of lead and other heavy metal poisoning, lowering of the toxicity of chemotherapy and radiation in cancer treatments, and reversal of cataracts. In one study, oral glutathione was able to reverse advanced liver cancer in rats (Novi, 1981). Other potential uses may be in increasing the recovery chances of stroke victims, preventing or even reversing liver cirrhosis, and alleviating arthritis, psychosis and allergy.

Cysteine itself, in addition to the detoxifying function that results from its ability to increase glutathione levels, has clinical uses ranging from baldness to psoriasis to preventing smoker's hack. N-acetylcysteine is available in liquid or aerosol and is great for mucus-burdened bronchial passages. In some cases, oral cysteine therapy has proved excellent for treatment of asthma, enabling asthmatics to stop theophylline and other medications.

Cysteine also enhances the effect of topically applied silver, tin and zinc salts in preventing dental cavities. In the future, cysteine may play a role in the treatment of cobalt toxicity, diabetes, psychosis, cancer and seizures.
At the Brain Bio Center, our standard dose of L-cysteine is 500 mg two times per day, often with selenium. Measurement of plasma sulfur amino acids can provide a guide to therapy.