Ornithine alpha-ketoglutarate (OKG) is manufactured from two amino acids, ornithine and glutamine. These amino acids are called “conditionally essential.” This means that ordinarily one does not need to consume them in food because the body can manufacture them from other nutrients. However, during periods of severe stress, such as recovery from major trauma or severe illness, the body may not be able to manufacture them in sufficient quantities, and may require an external source.

Ornithine and glutamine are thought to have anabolic effects, meaning that they stimulate the body to build muscle and other tissues. These amino acids also appear to have anti-catabolic effects. This is a closely related but slightly different property; ornithine and glutamine appear to block the effect of hormones that break down muscle and other tissues (catabolic hormones).

Evidence suggests that use of OKG (and related amino acids) may offer benefits for hospitalized patients recovering from serious illness or injury.

Based on these findings (and a leap of logic), OKG has been extensively marketed as a sports supplement for helping to build muscle. However, the fact that OKG helps seriously ill people build muscle does not mean that it will have the same effect in athletes, and there is no direct evidence to indicate that it does.

The amino acids that make up OKG are found in high-protein foods such as meat, fish, and dairy products. Supplements are available in tablet or pill form.