Ornithine is a nonessential amino acid that is structurally similar to arginine 
and is formed from arginine in the urea cycle within the body. For this reason, some researchers call ornithine “son of arginine”.
The popularity of ornithine among athletes is related to its effect on releasing growth hormone. Ornithine plays an important role in the urea cycle and act as a precursor for amino acids glutamic acid, proline and citrulline. Ornithine is also an important component of ornithine alphaketoglutarate (OKG). The anabolic effects of ornithine arise from its ability to increase GH and insulin levels.
Other effects attributed to ornithine are improving liver function in liver cirrhosis, accelerating wound healing, and effectiveness in treating burns. These findings, however, require independent confirmation.
Because of the above-mentioned effects, strength athletes such as weight lifters, sprinters, and bodybuilders may find ornithine very useful. It can be found in many high protein diets, for instance in meat and fish.
Dosage and Side Effects:
There is no standard dosage for ornithine. Dosages ranging from 2 to 15 grams per day have been used, but most researchers recommend using 2 to 5 grams before going to sleep. Using ornithine with glutamine, arginine or lysine enhances their effects. One study showed that 5 to 10 grams of arginine and 2.5 to 5 grams of ornithine taken before sleeping on an empty stomach elevated GH levels.
Even though no toxicity and side effects have been reported in up to 6 grams per day, consumption of large amounts of ornithine may cause indigestion, bloating, and diarrhea.
