Glutathione (GSH) has been the focus of increased scientific interest in the last decades. It plays a crucial role in all major physiological processes by supplying antioxidant defenses through participating in cellular redox reactions in the human body and other living organisms. GSH also participates in detoxifying xenobiotics, protecting protein thiols from crosslinking and oxidation, regulating the cell cycle, storing cysteine, etc. The significant role of GSH in the most important physiological processes has been highlighted, such as maintaining the redox balance and reducing oxidative stress due to its ability to inactivate the reactive oxygen, nitrogen, and sulfur species. It can also enhance metabolic detoxification and regulate the function of the immune system. All of these characteristics make it a universal biomarker since its proper balance is essential for improving health and treating some age-related disorders. This review presents a current concept of the synthesis and metabolism of GSH; its main functions in a living organism, and as a precursor and cofactor; data on the use of GSH for medicinal purposes in the prevention and treatment of some diseases, as well as a nutritional strategy to maintain a normal pool of GSH in the body. The data were gathered by searching relevant information in multiple databases, such as PubMed, Scopus, ScienceDirect, and Google Scholar.

alanine (BA), being a non-proteinogenic amino acid, is an important constituent of L-carnosine (LC), which is necessary for maintaining the muscle buffering capacity and preventing a loss of muscle mass associated with aging effects. BA is also very important for normal human metabolism due to the formation of a part of pantothenate, which is incorporated into coenzyme A. BA is synthesized in the liver, and its combination with histidine results in the formation of LC, which accumulates in the muscles and brain tissues and has a well-defined physiological role as a good buffer for the pH range of muscles that caused its rapidly increased popularity as ergogenic support to sports performance. The main antioxidant mechanisms of LC include reactive oxygen species (ROS) scavenging and chelation of metal ions. With age, the buffering capacity of muscles also declines due to reduced concentration of LC and sarcopenia. Moreover, LC acts as an antiglycation agent, ultimately reducing the development of degenerative diseases. LC has an anti-inflammatory effect in autoimmune diseases such as osteoarthritis. As histidine is always present in the human body in higher concentrations than BA, humans have to get BA from dietary sources to support the required amount of this critical constituent to supply the necessary amount of LC synthesis. Also, BA has other beneficial effects, such as preventing skin aging and intestinal damage, improving the stress-- fighting capability of the muscle cells, and managing an age-related decline in memory and learning. In this review, the results of a detailed analysis of the role and various beneficial properties of BA and LC from the anti-aging perspective.