Glutathione (GSH)

Forms/Synonyms:
Reduced L-glutathione

Chemical Name:
Gamma-L-glutamyl-L-cysteninylglycine.

Chemistry/Function:
L-Glutathione is a biologically active sulfur amino acid tripeptide compound containing three amino acids L-Cysteine, L-Glutamic Acid and Glycine. Most glutathione is found in the liver where it detoxifies many harmful compounds to be excreted thru the bile. Some glutathione can also be found in red and white blood cells, the lungs and the intestinal tract. The primary biological function of glutathione is to act as a non-enzymatic reducing agent to help keep cysteine thiol side chains in a reduced state on the surface of proteins. Reduced glutathione is involved in the synthesis and repair of DNA, helps to recycle vitamins C and E, blocks free radical damage and enhances the antioxidant activity of vitamin C, facilitates the transport of amino acids, and plays a critical role in the detoxification of harmful compounds. It is also the base material for several other key antioxidant enzyme systems including glutathione-peroxidase, glutathione-reductase, and glutathione-transferase. Declines in glutathione concentrations in intracellular fluids correlate directly with indicators of aging.

Dietary Sources:
Glutathione is derived from L-Cysteine, L-Glutamic Acid and Glycine and is not consumed directly as a food constituent. Glutathione levels are enhanced via intake of vitamin C.

Supplemental Sources:
A daily dose of 500 mg of vitamin C may be adequate to elevate and maintain reduced glutathione concentrations in the blood. In contrast, direct consumption of glutathione orally does not seem to be an effective means of enhancing liver and intracellular gltathione levels. Following a small human study with seven subjects Witschi et al concluded that "because of hydrolysis of glutathione by intestinal and hepatic gamma-glutamyltransferase, dietary glutathione is not a major determinant of circulating glutathione, and it is not possible to increase circulating glutathione to a clinically beneficial extent by the oral administration of a single dose of 3 g of glutathione". On the other hand, intravenous glutathione administration may provide a direct and effective route for increasing intracellualr glutathione levels. Evidence indicates that oral consumption of NAC (N-Acetyl-Cysteine) may be an effective, but not necessarily safe or efficient, means of enhancing glutathione levels.
(Johnston CS, et al. Am J Clin Nutr. 1993 Jul;58(1):103-105; Witschi A, et al. Eur J Clin Pharmacol. 1992;43(6):667-669.)

Deficiency:
Symptoms of glutathione deficiency may include coordination problems, generalized cell damage, mental disorders, various nervous system disorders, tremors, and twitching. Red cells are prone to burst, white blood cells decline in function, and nerve tissue degenerates. A deficiency of intracellular glutathione has been associated with a variety of conditions including AIDS, alcohol-induced liver disease and some forms of cancer.

Proven or Potential Therapeutic Uses:
Antioxidant action, cancer, cataracts, liver disease, macular degeneration.

Mechanism:
Support of antidoxidant processes.

Maintenance Dose:
Usually not necessary. Optimal levels of intake have not been established. 50 mg is a common dose in supplemental forms.

Therapeutic Dose:
500 mg a day is used by some practitioners to treat various conditions.

Side Effects:
Glutathione is generally considered to be free of side effects.

Toxicity:
No toxicities have been reported or suspected as being associated with glutathione.

Contraindications:
None known, except for use during some forms of chemotherapy and radiation where antioxidants are contraindicated due to their inhibition of the free radical formation which is an intentional part of the therapeutic mechanism.

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