Glutathione is a powerful antioxidant that is produced in the liver. The largest stores of glutathione are found in the liver, where it detoxifies harmful compounds so that they can be excreted through the bile. Some glutathione is released from  the liver directly into the bloodstream, where it helps to maintain the integrity of the red blood cells and protect white blood cells. Glutathione is also found in the lungs and the intestinal tract. It is needed for carbohydrate metabolism and appears to exert anti-aging effects, aiding in the breakdown of oxidized fats  that may contribute to atherosclerosis. 

It can mitigate some of the damage caused by tobacco smoke because it modifies  the harmful effects of aldehydes, chemicals present in cigarette smoke that damage cells and molecules and it may protect the liver from alcohol induced  damage.  

A deficiency of glutathione first affects the nervous system, causing such symptoms as lack of coordination, mental disorders, tremors, and difficulty maintaining balance. These problems are believed to be due to the development of lesions in the brain. A study sponsored in part by the National Cancer Institute found that people with HIV disease who had low glutathione levels had a lower survival rate over a three-year period than those whose glutathione levels were normal. As we age, glutathione levels decline, although it is not known whether this is because we use it more rapidly or produce less of it to begin with. Unfortunately, if not corrected, the lack of glutathione in turn accelerates the aging process.