Glutathione is involved in many processes in the body, including tissue building and repair, making chemicals and proteins needed in the body, and for the immune system. Glutathione is a substance produced naturally by the liver.
People take glutathione by mouth for treating cataracts and glaucoma, preventing aging, treating or preventing alcoholism, asthma, cancer, heart disease (atherosclerosis and high cholesterol), hepatitis, liver disease, diseases that weaken the body’s defense system (including AIDS and chronic fatigue syndrome), memory loss, Alzheimer’s disease, osteoarthritis, and Parkinson’s disease. Glutathione is also used for maintaining the body’s defense system (immune system) and fighting metal and drug poisoning. Glutathione is breathed in (inhaled) for treating lung diseases, including idiopathic pulmonary fibrosis, cystic fibrosis, and lung disease in people with HIV disease.
Healthcare providers give glutathione as a shot (by injection into the muscle) for preventing poisonous side effects of cancer treatment (chemotherapy) and for treating the inability to father a child (male infertility). Healthcare providers also give glutathione intravenously (by injection into the vein, by IV) for preventing “tired blood” (anemia) in kidney patients undergoing hemodialysis treatment, preventing kidney problems after heart bypass surgery, treating Parkinson’s disease, improving blood flow and decreasing clotting in individuals with “hardening of the arteries” (atherosclerosis), treating diabetes, and preventing toxic side effects of chemotherapy.

What is Glutathione?

Glutathione is a sulfur-containing amino acid that is an important part of the body's antioxidant defense system. Glutathione is composed of three different amino acids: cysteine, glutamic acid, and glycine. Vitamins B6 and riboflavin are critical for maintaining adequate levels of glutathione within the body.
Research suggests that a variety of minerals, including copper and selenium, have a strong influence on cellular levels of glutathione. In addition, selenium is an essential part of many different forms of glutathione that exist in the body. Because of its antioxidant properties, glutathione neutralizes damaging free radicals and peroxide molecules, and recharges oxidized vitamin C, so that the body may reuse it. Glutathione is required for a variety of metabolic processes. In addition, glutathione bolsters the structure of body proteins and assists in the transport of amino acids across cell membranes.

How is it Made?
Glutathione is not an essential nutrient, since it can be synthesized from the amino acids L-cysteine, L-glutamic acid, and glycine. The sulfhydryl (thiol) group (SH) of cysteine serves as a proton donor and is responsible for the biological activity of glutathione. Provision of this amino acid is the rate-limiting factor in glutathione synthesis by the cells, since cysteine is relatively rare in foodstuffs. Furthermore, if released as the free amino acid, cysteine is toxic and spontaneously catabolized in the gastrointestinal tract and blood plasma.
Glutathione is synthesized in two adenosine triphosphate-dependent steps:

Dosage
When taken by mouth, most glutathione dosages range from 50 mg to 600 mg. However, it should be noted that research suggests that glutathione is not significantly absorbed into the body when taken by mouth (so Scientists have also developed sublingual form of Glutathione). When inhaled, a dose of 600 mg twice daily has been recommended. When given as an intramuscular injection, a dose of 600 mg every day or every other day has been suggested by some clinical studies. A few studies that have used glutathione intravenously (IV) have used doses based on body surface area (a measure calculated using your height and weight). The best way to increase Glutathione is to consume its precursor like NAC, which is highly absorbed in the body.

Possible Side effects / Precautions / Possible Interactions
Glutathione is possibly safe for most adults when taken by mouth, by inhalation, or by injection into the muscle or into the veins. But the possible side effects are not known.

Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the use of glutathione during pregnancy and breast-feeding. Stay on the safe side and avoid use.
Asthma: Do not inhale glutathione if you have asthma. It can increase some asthma symptoms.

Research Studies / References