GSH is one of the most extensively studied chemicals of the human body and its decline with aging and disease risk is well established. GSH is needed both for maintenance of normal metabolism and for defense against a range of disease and toxicity mechanisms. GSH is maintained by continuous processes of GSSG reduction and GSH transport, degradation, and synthesis. GSH concentrations are considerably higher in tissues than in most body fluids, but the fluid concentrations are important because they protect cell surfaces and support protective barrier defenses. Extensive research in model systems establishes that GSH is transported by cells and that added GSH protects against a range of chemical and infectious threats. Although most Americans consume an adequate supply of dietary precursors for GSH synthesis, there is a gap between the amount synthesized and the amount needed (ie, a decline in GSH is associated with disease risk). Based upon the loss of GSH from food during processing and the measured contents of reactive chemicals in food, this gap can be estimated to be 300 mg/day. However, higher values may be needed to compensate for adverse environmental conditions and disease, but the possible amounts can only be speculated.
Because the American healthcare system is approaching crisis with the ballooning costs of late-stage disease treatment, cost-effective means are needed to preserve health. Available (but not FDA-approved) methods allow prospective assessment of GSH in individuals prior to disease onset, and health maintenance programs are beginning to adopt GSH analysis as part of quantitative health assessment (but not disease treatment). Simple strategies, including supply of GSH, GSH precursors, complementary antioxidants, and zinc, are available to improve GSH status in individuals with low or oxidized GSH. Such strategies could have considerable personal and societal health and economic impact.