Glutathione and the enzymes that it forms, such as GTH peroxidase, are essential to life and are present in all cells of both plants and animals. In humans, GTH is found in all tissues, with the highest levels found in the liver, lenses of the eyes, spleen, pancreas, and kidneys. It is a key protector from the potential damage by wastes and toxins and is effective in preventing aging. GTH functions as a:

Reducing agent—protects against oxidation.

Antioxidant (actually an antitoxin as part of an enzyme system that helps protect against environmental and metabolic toxins)—protects against peroxidation. Lipid peroxides alter unsaturated lipids in cell membranes. Peroxides are also potent free radicals. (Like hydrogen peroxide, H2O2, peroxides release oxygen, which can destroy bacteria and parasites, as well as our own cells if they are not protected by all of the nutritional antioxidants.) Some chemicals that increase peroxidation include pesticides, plastics, benzene, and carbon tetrachloride. Glutathione protects against these as well as heavy metals, cigarette smoke, smog, carbon monoxide from cars, drugs, solvents, dyes, phenols, and nitrates. GTH transferase helps to detoxify these chemicals into less toxic forms. It is possible that future uses will allow us to use some form of glutathione to clean up our environment.

An immune helper—GTH helps get nutrients and amino acids to the lymphocytes and phagocytes, thus helping cells combat immunity.

Aids integrity of red blood cells—and really the protection of all cells and membranes.


(AS L-cysteine)


Cigarette smoke

Radiation exposure

Metal toxicity

Chemical exposure

Drug use




Stroke and brain injury


Skin problems


Glutathione’s main uses are to combat all types of pollution and many irritated body states, often those generated by chemical use. As I said, due to cost and actual usability, GTH itself is not usually taken as a supplement (though available as such) but is obtained from L-cysteine or L-methionine (not the D- forms). Since L-cysteine is handled better and is a more direct precursor of GTH, it is supplemented in amounts of 500 mg. daily (250 mg. twice daily) up to 2–3 grams daily. Vitamin C is usually recommended by many authors in doses at least three times that of L-cysteine to facilitate the function of L-cysteine. In general, patients should not take more than 1 gram daily of L-cysteine without being monitored by a physician. Though not all the research is supportive of this method of generating glutathione, apparently it is currently the best way to increase glutathione levels in the body. Up to 200–300 mcg. daily of extra selenium is also given for its antioxidant support, usually along with vitamin E, but not with vitamin C. Vitamin C may increase the conversion of selenite, a common form of supplemental selenium, to its more toxic form, elemental selenium.

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Written by Elson M. Haas MD

Explore Wellness in 2021