What is glutathione as a therapeutic supplement?

Overview

Dangerous naturally occurring substances in the body called free radicals
pose a risk to many tissues. The body deploys an antioxidant defense system to
hold free radicals in check. Glutathione, a protein made from the amino acids
cysteine, glutamic acid, and glycine, is one of the most important elements of
this system.

Glutathione does much of its work in the liver, although it is also found elsewhere in the body. Besides fighting free radicals, it helps keep various essential biological molecules in a chemical state called reduced (as opposed to oxidized). In addition, glutathione can act on toxins such as pesticides, lead, and dry cleaning solvents, transforming them in such a way that the body can excrete them more easily.

Nutrients such as vitamin C and vitamin E
also help neutralize free radicals. In the 1990s, such antioxidant supplements
were widely promoted for preventing a variety of diseases, including cancer and
heart disease. During this period, oral glutathione became popular as an
additional antioxidant supplement. Glutathione is not absorbed when taken by
mouth, so such supplements are almost certainly useless. It may be possible,
however, to raise glutathione levels in the body by taking other supplements, such
as vitamin C, cysteine, lipoic acid, and N-acetylcysteine. Whether doing so would offer any health
benefits remains unclear.

Requirements and Sources

There is no dietary requirement for glutathione. The body makes it from scratch, utilizing vitamins and common amino acids found in food. Glutathione levels in the body are reduced by cigarette smoking. Various diseases are associated with reduced levels of glutathione, including cancer, cataracts, diabetes, and human immunodeficiency virus (HIV) infection.

Therapeutic Dosages

A typical recommended dose of oral glutathione is 50 milligrams twice daily. However, as noted above, when glutathione is taken by mouth it is destroyed. Therefore, no matter what the dose, it will not make any difference. It is possible that some glutathione may be absorbed if it is held in the mouth and allowed to dissolve, but this has not been well studied.

A more promising method for raising glutathione levels in the body involves
taking supplemental cysteine or antioxidant supplements. Evidence
suggests that cysteine (often supplied in the form of whey protein, which is high
in cysteine) can raise glutathione levels in people with cancer, hepatitis, or
HIV.

In addition, because vitamin C has overlapping functions with glutathione,
vitamin C supplements may spare some of the body’s glutathione from being used up,
thereby increasing its levels in the body. The antioxidant supplement lipoic acid
appears to raise glutathione levels as well. Other supplements that might raise
glutathione levels include N-acetylcysteine, glutamine,
methionine, and S-adenosyl methionine (SAMe).

Therapeutic Uses

Various Web sites promote glutathione for a wide variety of health problems, from preventing aging to enhancing sports performance. However, oral glutathione supplements are almost certainly useless for any condition, since they are not absorbed.

There is a bit of evidence that injected glutathione might offer a few health benefits, such as preventing blood clots during surgery, reducing the side effects and increasing the effectiveness of cancer chemotherapy drugs such as cisplatin, treating male infertility, and alleviating symptoms of early Parkinson’s disease. Although oral glutathione is not likely to provide the same benefits, it is at least theoretically possible that taking the nutrients described in the previous section (and thereby raising glutathione levels indirectly) could offer similar benefits. However, there is no direct evidence to indicate that this hypothesis is true.

Safety Issues

Oral glutathione should be entirely safe, since it is not absorbed.

Bibliography

Bharath, S., et al. “Glutathione, Iron, and Parkinson’s Disease.” Biochemical Pharmacology 64 (2002): 1037-1048.

Bounous, G. “Whey Protein Concentrate (WPC) and Glutathione Modulation in Cancer Treatment.” Anticancer Research 20 (2000): 4785-4792.

De Rosa, S. C., et al. “N-Acetylcysteine Replenishes Glutathione in HIV Infection.” European Journal of Clinical Investigation 30 (2000): 915-929.

Droge, W., and R. Breitkreutz. “Glutathione and Immune Function.” Proceedings of the Nutrition Society 59 (2000): 595-600.

Hultberg, B., et al. “Lipoic Acid Increases Glutathione Production and Enhances the Effect of Mercury in Human Cell Lines.” Toxicology 175 (2002): 103-110.

Lenzi, A., et al. “Lipoperoxidation Damage of Spermatozoa Polyunsaturated Fatty Acids (PUFA): Scavenger Mechanisms and Possible Scavenger Therapies.” Frontiers in Bioscience 5 (January, 2000): E1-E15.

Packer, L., et al. “Molecular Aspects of Lipoic Acid in the Prevention of Diabetes Complications.” Nutrition 17 (2001): 888-895.