Effects of Supplementation with Glutathione and its Precursors on Athlete Performance
Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2019, Vol 12, Issue 4
Abstract
Glutathione (GSH) is a thiol-containing tripeptide consisting of glutamate (Glu), cysteine (Cys) and glycine (Gly), which plays central roles in the defense against oxidative damage and in signaling pathways. The cellular concentration of GSH and its oxidative state (GSSG), and their molar ratio are indicators of cell functionality and redox state. Glutathione is the most important antioxidant in human organism. Its level can be increased by supplementation with glutathione precursors. Furthermore, glutathione is the most popular drug (supplement) used by athletes and people remaining in physical activity. The increase in GSH body content can be achieved by supplementation with N-acetyl-L-cysteine (NAC), α- lipoic acid (ALA), whey preparation or L-glutamine. There are many scientific reports showing a key role of glutathione in treatment of many diseases. Furthermore, authors demonstrated improvement of the sport performance and physical condition of athletes by supplementation of glutathione and glutathione precursors.Intensive exercise is related to an increased generation of reactive oxygen species (ROS), the main cause of oxidative stress, as a consequence of higher energy demand [1,2]. In active tissues such as skeletal muscles, ROS activity results mainly from mitochondria damage and may impair the muscle force production. Therefore, many athletes consume antioxidant supplements to suppress muscle fatigue or to facilitate the process of recovery. Whether such antioxidant supplementation has beneficial effects on sport performance and health is a matter of controversy which seems to stem from considerable differences in study designs [3]. Some authors report that antioxidant supplementation, especially a prolonged one, may have deleterious effects on health and sport performance, e.g. by down regulating natural ROS quenching mechanisms or hampering organism adaptation to increased physical exercise [4-8]. Such results are in line with the free radical theory of development which posits that formation of reactive species plays a very important role in development of organisms and their adaptation to environmental changes [9]. Other studies report that antioxidant supplementation may lead to increased sport performance or shortens the process of post-exercise recovery; the effects highly desired by competitive athletes. A common feature of those studies seems to be a short and acute supplementation period, usually a few days or weeks long, which perhaps still allows for triggering the adaptation mechanisms in response to increased production of ROS. These studies are of the main interest of this review.Glutathione (γ-L-glutamyl-L-cysteinyl-glycine, GSH) plays a very important role in physical exercise by controlling the level of oxidative stress. It is the major endogenous intracellular antioxidant and currently one of the most studied substances of this class. It is synthesized primarily in the hepatic cells and has numerous physiological functions, including protection of cells against oxidative stress, detoxication of toxins and carcinogens, posttranslational regulation of protein function, and maintenance of immune function of the immune system. In human body, GSH is synthesized by sequential addition of the precursor amino acids, cysteine (Cys), glutamic acid (Glu) and glycine (Gly), through enzymatic catalysis by two ATP-dependent enzymes namely, glutamate cysteine ligase (GCL) and GSH synthetase (GS) [10,11].
Authors and Affiliations
Krzysztof Grucza, Piotr Chołbiński, Dorota Kwiatkowska, Mirosław Szutowski
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