Glutathione is a substance naturally produced by the human body through the synthesis of certain amino acids in the liver. It's also used by virtually every cell of the body to neutralize toxins. Since glutathione is composed of three amino acids, namely gamma-glutamic acid, cysteine, and glycine, it is classified as a tripeptide. However, unlike some other tripeptides, it possesses a unique peptide linking structure within the cysteine and glutamate chain. The thiol group in the former allows the molecule to provide what is known as a reducing equivalent, which means the ability to donate one electron to other molecules rendered unstable and highly reactive due to a lack of balanced electron pairs. For this reason, this form is called reduced glutathione (GHS).
The majority of this substance found in the cells and tissue of the body is in the GHS state. However, as electron donation continues, GHS molecules also become unstable due to unpaired electrons and eventually bind to a fellow molecule to create an oxidized form, or glutathione disulfide (GSSG). Of total glutathione concentration in the body, only 10% resides as GSSG.
The primary function of glutathione is to provide antioxidant activity by regulating the reduction of cysteine thiol side chains as they adhere to proteins. This action helps to deter oxidative stress and cellular damage from free radicals. In fact, this substance is essential to protect the eyes, skin, kidneys, liver and many other organs from toxic byproducts produced by the body through normal metabolism. In the liver, it aids in the detoxification and removal of harmful toxins, including those generated through environmental pollution, and the consumption of alcohol and drugs.
Glutathione also plays an important role in promoting a healthy immune system. For instance, it inhibits inflammatory mediators, such as leukotrienes, which are involved in a variety of inflammatory disorders ranging from allergies to arthritis. Since research has shown a link between decreased glutathione availability and age-related diseases, experimental therapy is underway to help treat many age-related conditions, such as cancer, Alzheimer’s disease and Parkinson’s disease. There is also evidence to suggest that people afflicted with an autoimmune disorder, such as AIDS, may be deficient in this substance and may benefit from supplementation.
While several studies have demonstrated the beneficial properties of glutathione, evidence that oral supplementation has any therapeutic value is less promising. For one thing, it is not well absorbed in supplement form. For another, studies have shown that a supplemental dose does not necessarily increase levels circulating in the body, even if taken intravenously. However, increasing intake of cysteine, a precursor to glutathione, may increase available levels in cells. Studies have shown that S-Adenosylmethionine (SAM-e), N-acetylcysteine (NAC), and supplements made from unadulterated whey protein, raise cysteine levels.
While glutathione supplementation is generally considered safe, there are certain risks and side effects to consider. Individuals with an allergy to milk protein (casein), for instance, should not take it. In addition, patients undergoing immune suppressive therapy should not take glutathione, including individuals that have received an organ transplant. There have also been reports of intestinal cramping and bloating, particularly if water intake is not increased.