9. GSH: Barometer of Oxidative Stress

In oxidative protection, it seems that all roads lead to GSH, the fundamental "reducing" agent in the body. Many scientists now use GSH levels as a general measure of oxidative stress. For instance, when GSH quenches a radical, it typically oxidizes to GSSG (glutathione disulfide). The measurement of the oxidative balance of a cell or a cellular process is usually based directly on the ratio of GSH to GSSG.³¹

GSH is found in every cell in the body.

• GSH can be incorporated into antioxidant enzymes, such as glutathione peroxidase (GPX).
• GSH is the prime protector of all sulfur-bearing proteins and enzymes, thanks to its sulfhydryl unit (-SH).
• GSH is present in essentially all (mammalian) cells.
• GSH can support SOD activity by filling in for SOD's usual partner, catalase.³²
• GSH recycles vitamins C and E and other antioxidants to their active forms.³³
• GSH is the "antioxidant-of-choice" for immune cells and other highly oxidative tissues.³⁴
• GSH is a detoxifier within many cells.
• GSH plays a major role in the detoxifying activity of the liver.³⁵
• GSH is the "partner" of vitamin E in protecting membranes from radical damage.

From this partial list, we can begin to see why GSH is called "the master antioxidant" of the body.³⁶