Ornithine Alpha-ketoglutarate (OKG)
Ornithine alpha-ketoglutarate, abbreviated OKG, also known as ornithine 2-oxoglutarate or ornithine oxoglutarate (OGO), is a salt formed of two molecules of the non-protein amino acid, L-ornithine, and one molecule of the Krebs cycle dicarboxylic acid, alpha-ketoglutarate. OKG has been used both enterally and parenterally in burn, trauma, surgical and chronically malnourished patients. It appears to decrease protein catabolism and/or increase protein synthesis under these conditions. OKG is a popular nutritional supplement for athletes, among others.
Ornithine alpha-ketoglutarate (OKG) is a salt formed by combining two molecules of the amino acid ornithine and one molecule of alpha-ketoglutarate. Because OKG seems to be involved in amino acid synthesis and protein availability, many athletes supplement with OKG as a way to increase muscle mass and strength – although the evidence for its effectiveness is this regard is quite limited. OKG has been used to treat patients suffering from burns, surgery, malnutrition and other trauma. Although the precise mechanism is unknown, OKG treatment decreases muscle protein catabolism (breakdown) and/or increases protein synthesis, in addition to promoting wound healing. OKG may promote the secretion of anabolic hormones such as insulin and growth hormone and increase amino acid metabolism (glutamine & arginine), which may help explain some of the clinical findings.
The actions of OKG can be attributed to the metabolites that the OKG components, L-ornithine and alpha-ketoglutarate, give rise to. These metabolites are L-arginine, L-glutamine, L-proline and polyamines. The metabolism of L-glutamine and L-arginine is altered in trauma, and this alteration is linked to immune dysfunction. One of the major biochemical events that occurs following a burn injury is a fall in intramuscular L-glutamine. This amino acid is released from muscle tissue to meet the increased needs of other cells, in particular immune cells and intestinal cells. L-glutamine is now known to be essential for sustaining the proliferation and activation of immune cells. In the intestine it is essential for maintaining the integrity of the mucosal barrier and its metabolic and immune function. Immune and gastrointestinal dysfunctions occur when de novo L-glutamine synthesis is insufficient to maintain normal function of immune cells and enterocytes. Under these conditions, for example a burn injury, the normally non-essential (meaning the body can make it) L-glutamine becomes a conditionally essential amino acid (meaning the body can't make enough of it). OKG is a delivery form of L-glutamine.
L-arginine is also essential for immune cells. It is thought that the role of L-arginine in immunity is mediated by its metabolite nitric oxide. Burn injury and some other traumas affect the status of both L-glutamine and L-arginine in the various tissues of the body, especially muscle, the immune system and the gastrointestinal tract. As in the case of L-glutamine, de novo synthesis of L-arginine during these conditions is probably not sufficient for normal immune and gastrointestinal function, nor for normal protein synthesis. OKG, in addition to being a delivery form of L-glutamine, is also a delivery form of L-arginine or more precisely L-ornithine, which is converted to L-arginine.