Description
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.
Claims
Increase muscle size and strength
Reduce body fat
Stimulates the immune system
Theory
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.
Scientific Support
Arginine and ornithine are precursors of nitric oxide and polyamines, respectively -metabolites which participate in a number of metabolic functions. OKG supplements have been shown to promote growth hormone and insulin secretion with anabolic effects in postoperative patients. Their intermediary metabolites (glutamine & proline) may also have beneficial effects in promoting recovery from trauma. In animal studies, OKG supplementation increases levels of arginine and glutamine in skeletal muscles and stimulates immune system function compared to animals not receiving OKG. The immunomodulatory properties found with OKG suggest that it may enhance host-defense mechanisms, particularly during injury and acute stress
OKG supplements (15 grams per day for 5 months) have been shown to improve growth rates in small children. The OKG supplements resulted in elevated concentrations of anabolic (growth) hormones and amino acid metabolites, including insulin-like growth factor 1 (IGF1), glutamine and glutamate. In another study of healthy men, OKG given at 10 grams per day resulted in a 20-30% elevation in insulin (another anabolic hormone), which were not observed with supplementation of either ornithine or alpha-ketoglutarate alone.
A test tube study found that OKG induces a significant increase in growth of human fibroblasts – cells with similarities to muscle fiber cells. This effect was dose-dependent, meaning that a more pronounced growth effect was noted with increasing levels of OKG (but not with increasing levels of ornithine or alpha-ketoglutarate alone).
In one study, the anti-catabolic effects of OKG were investigated in 14 multiple trauma patients who were highly catabolic and hyper-metabolic. One group of subjects received 20 grams of OKG per day and showed a significant increase in protein turnover as well as a an increase in blood levels of insulin, growth hormone, and free amino acids (glutamine, proline and ornithine) compared to subjects not receiving OKG supplements.
Safety
No apparent side effects have been noted with OKG supplementation at the doses studied (10-15 grams/day), although there have been anecdotal reports of increased appetite – perhaps owing to elevated insulin levels (??).
Value
OKG supplements, taken at a dose shown to produce effects (10-15 grams per day) is a fairly expensive regimen. At $30-$35 per 100 capsule bottle (1250 mg capsules), a one month supply will cost over $100. For stimulating increases in muscle mass, creatine may be able to provide the same end benefit – at a much lower cost per day.
Dosage
OKG has been used at doses of 10-15 grams per day in healthy men and short-stature children.
References
1. Cochard A, Guilhermet R, Bonneau M. Plasma growth hormone (GH), insulin and amino acid responses to arginine with or without aspartic acid in pigs. Effect of the dose. Reprod Nutr Dev 1998 May-Jun;38(3):331-43.
2. Jeevanandam M, Petersen SR. Substrate fuel kinetics in enterally fed trauma patients supplemented with ornithine alpha ketoglutarate. Clin Nutr 1999 Aug;18(4):209-17.
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