Login or Register

Amino Acid L-Ornithine

Mar 28, 2011 | By Owen Bond

Ornithine is created when another amino acid, arginine, is metabolized during the production of urea, a component of urine. Thus, ornithine is not an amino acid coded by human DNA, nor is it involved in protein synthesis. Along with arginine, ornithine may play a role in building muscle tissue by elevating levels of insulin and human growth hormone, which is why it is a popular supplement for bodybuilders and other athletes. The L-form refers to the orientation of the molecule that is best recognized by the body.

Functions of Ornithine

According to "Advanced Nutrition: Macronutrients, Micronutrients and Metabolism," ornithine is one of the products from the action of the enzyme arginase on arginine, which eventually produces urea. Thus, ornithine plays a central role in the urea cycle, which allows for the disposal of excess nitrogen via the urine. Ornithine is recycled within the body and probably best thought of as a catalyst.

Uses of Ornithine

Commercially, ornithine is synthesized from glutamate within bacteria, such as E. coli; it is sold as a supplement, often along with arginine. The most common reason for supplementing with ornithine and arginine is to stimulate the production and release of certain hormones. According to "Nutritional Sciences," research from various animal studies has shown that ornithine, combined with arginine, may play a part in building muscle tissue by elevating circulating levels of anabolic growth-supporting hormones including insulin and human growth hormone. An older study published in a 1989 edition of the "Journal of Sports Medicine and Physical Fitness" found that taking 2 g of ornithine and arginine daily increased lean muscle mass and strength in adult males. Not surprisingly, ornithine and arginine are popular supplements among bodybuilders and other athletes, despite a relative lack of additional supportive research. Another, more ominous use of ornithine is as an ingredient for cocaine biosynthesis.

Other Health Uses of Ornithine

Other clinical studies have confirmed different health uses for ornithine. A study published in the July 1994 edition of "Age and Aging" found that supplements of ornithine alpha-ketoglutarate helped improve appetite, weight gain and quality of life for people with acute illnesses. Further, a 1998 study published in the "Journal of Nutrition" demonstrated that ornithine alpha-ketoglutarate supplements improved wound healing and decreased hospital stays in people with severe burns. Unfortunately, more current studies on the effects of ornithine on humans are lacking or of poor quality.

Dosages of Ornithine

In some studies, daily dosages reached 30 g of ornithine without serious side effects. In general, dosages up to 10 g daily are considered safe and without side effects, although gastrointestinal complaints have been noted with dosages of more than 10 g daily. According to "Contemporary Nutrition: Functional Approach," mega-dosing arginine causes even fewer side effects, but will lead to production of ornithine within the body; combining the two amino acids might be somewhat redundant.

References

Article reviewed by Mia Paul Last updated on: Mar 28, 2011

Must see: Photo Galleries

Member Comments