Glutathione (GSH - a tripeptide consisting of glutamic acid - cysteine - glycine), acts as the substrate for the enzyme glutathione peroxidase. It is also the product of the enzyme glutathione reductase. GSH is the major intracellular antioxidant, protecting cytosolic organelles in particular from the damaging effects of the many oxidative and nitrosative substances formed during normal metabolism and xenobiotic detoxification. In addition, GSH also acts synergistically with ascorbic acid and alpha-tocopherol to re-cycle these nutrient antioxidant vitamins to their reduced state after their interaction with reducing chemical species inside the cell. Dietary sources of glutathione are found in fresh fruit and vegetables and it has been suggested that deficiency in the consumption of these is an important factor in the development of many cancers .
No supplements for at least 24 hours before the test.
In glutathione synthetase deficiency (5-oxoprolinuria), as well as in nutritional deficiency, the total level of GSH in the red cells is reduced. Enzyme-deficient subjects may be identified by studying the stability of the enzyme and affected individuals may also suffer from chronic haemolysis and late-onset intellectual regression.
Green (lithium heparin)