Glutathione

IMMUNOCAL is a natural food protein concentrate in the FDA category of GRAS (generallyrecognized as safe) which assists the body in maintaining optimal concentrations of glutathione(GSH) by supplying the precursors required for intracellular glutathione synthesis. It is clinicallyproven to raise glutathione values (Lands et al, 1999). It has been certified in more than 20 countriesand has over 65 patents.Glutathione is a tripeptide made intracellularly from its constituent amino acids L-glutamate, L-cysteine and glycine. The sulfhydryl (thiol) group (SH) of cysteine serves as a proton donor and isresponsible for the biological activity of glutathione. Provision of this amino acid is the rate-limitingfactor in glutathione synthesis by the cells since cysteine is relatively rare in foodstuffs andfurthermore, if released as the free amino acid, is toxic and spontaneously catabolized in thegastrointestinal tract and blood plasma.Immunocal® is a bovine whey protein isolate specially prepared so as to provide a rich source ofbioavailable cysteine. Following digestion, the cysteine remains as the stable form cystine (2molecules of cysteine linked by disulfide bond) and glutamylcystine. After absorption, thesedipeptides travel safely in the blood stream and readily enter the cells to release free cysteine forintracellular glutathione synthesis. Immunocal® can thus be viewed as a cysteine delivery system.The disulphide bond in cystine is pepsin and trypsin resistant but may be split by heat, low pH ormechanical stress releasing free cysteine. When subject to heat or shearing forces (inherent in mostextraction processes), the fragile disulfide bonds within the peptides are broken and the bioavailabilityof cysteine is greatly diminished.Glutathione is a tightly regulated intracellular constituent and is limited in its production by negativefeedback inhibition of its own synthesis through the enzyme gamma-glutamylcysteine synthetase,thus greatly minimizing any possibility of overdosage.Glutathione has multiple functions:1. It is the major endogenous antioxidant produced by the cells, participating directly in theneutralization of free radicals and reactive oxygen compounds, as well as maintainingexogenous antioxidants such as vitamins C and E in their reduced (active) forms.2. Through direct conjugation, it detoxifies many xenobiotics (foreign compounds) andcarcinogens, both organic and inorganic.3. It is essential for the immune system to exert its full potential, e.g. (1) modulating antigenpresentation to lymphocytes, thereby influencing cytokine production and type of response(cellular or humoral) that develops, (2) enhancing proliferation of lymphocytes therebyincreasing magnitude of response, (3) enhancing killing activity of cytotoxic T cells and NKcells, and (4) regulating apoptosis, thereby maintaining control of the immune response