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What is ornithine? Why do we need it?

Ornithine is an amino acid manufactured by the body. It is produced when another amino acid, arginine, is metabolized during the production of urea, a substance found in human urine. It plays an important role in the metabolism of nitrogen and is believed to stimulate the release of growth hormones.

Several studies have been conducted on the benefits of ornithine, primarily in body builders. Some studies have found that a combination of ornithine and arginine may promote muscle-building activity; other studies have reported increases in lean muscle mass and strength, but these studies have yet to be confirmed independently.

Other clinical studies have found different uses for ornithine. A 1994 study on people with acute illnesses suggested that supplements of ornithine alpha-ketoglutarate helped improve appetite, weight gain and quality of life. Another study conducted in 1998 showed that ornithine alpha-ketoglutarate supplementation improved wound healing and decreased hospital stays in people with severe burns.

How much ornithine should I take?

Most people do not benefit from ornithine supplementation. However, the vast majority of human ornithine studies involve between 5-10 grams of the substance, sometimes in combination with arginine. Some sports physicians recommend between 1,500-2,500mg of ornithine twice daily to stimulate muscle growth.

What are some good sources of ornithine? What forms are available?

In addition to being produced naturally by the body, ornithine can be found in meat, fish, dairy products and eggs. The typical Western diet provides about five grams of ornithine per day.

What can happen if I don't get enough ornithine? What can happen if I take too much? Are there any side-effects I should be aware of?

Since ornithine is produced naturally, it is highly unlikely a deficiency would occur; however, pregnant women and people who have suffered severe trauma or malnutrition may become ornithine deficient. Some patients have experienced gastrointestinal disturbances and insomnia when taking more than 10 grams of ornithine per day.

As of this writing, there are no known drug interactions with ornithine.


  • Brocker P, Vellas B, Albarede JL, Poynard T. A two-centre, randomized, double-blind trial of ornithine oxoglutarate in 194 elderly, ambulatory, convalescent subjects. Age Ageing 1994;23:303—6.
  • Bucci LR, Hickson JF, Wolinsky I, et al. Ornithine supplementation and insulin release in bodybuilders. Int J Sport Nutr 1992;2:287—91.
  • De Bandt JP, Coudray-Lucas C, Lioret N, et al. A randomized controlled trial of the influence of the mode of enteral ornithine alpha-ketoglutarate administration in burn patients. J Nutr 1998;128:563—9.
  • Elam RP, Hardin DH, Sutton RA, et al. Effects of arginine and ornithine on strength, lean body mass and urinary hydroxyproline in adult males. J Sports Med Phys Fitness 1989;29:52—6.
  • Zieve L. Conditional deficiencies of ornithine or arginine. J Am Coll Nutr 1986;5:167-76.
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