Glutathione is a major antioxidant acting as a free radical scavenger that protects the cell from reactive oxygen species (ROS). Sulfur amino acids (SAAs), such as methionine and cysteine, play a critical role in the maintenance of health. GSH depletion as well as alterations of SAA metabolism are linked to a host of disease states including liver cirrhosis, various pulmonary diseases, myocardial ischemia and reperfusion injury, aging, Parkinson's disease, Alzheimer's disease, sepsis, and others. This book provides researchers with a comprehensive review of the biochemistry, absorption, metabolism, biological activities, disease prevention, and health promotion of glutathione and sulfur amino acids.