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Ornithine, an amino acid, is manufactured by the body when another amino acid, arginine, is metabolized during the production of urea (a constituent of urine).
As with amino acids in general, ornithine is predominantly found in meat, fish, dairy, and eggs. Western diets typically provide 5 grams per day. The body also produces ornithine.
Some athletes say that ornithine
Ornithine in large amounts has raised levels of growth hormone in some athletes, while smaller amounts had no effect. Some research has demonstrated benefits of combining arginine and ornithine, but this research needs to be independently confirmed.
Large quantities (170 mg per 2.2 pounds of body weight per day) of a the amino acid ornithine have raised growth hormone levels in some athletes.1 High amounts of arginine (another amino acid) or ornithine do not appear to raise levels of insulin,2 3 another anabolic (bodybuilding) hormone. More modest amounts of a combination of these amino acids have not had measurable effects on any anabolic hormone levels during exercise.4 5
Nonetheless, double-blind trials conducted by one group of researchers, combining weight training with either arginine and ornithine (500 mg of each, twice per day, five times per week) or placebo, found the amino-acid combination produced decreases in body fat,6 resulted in higher total strength and lean body mass, and reduced evidence of tissue breakdown after only five weeks.7
No side effects have been reported with the use of ornithine, except for gastrointestinal distress with intakes over 10 grams per day.
The presence of arginine is needed to produce ornithine in the body, so higher levels of this amino acid should increase ornithine production.
At the time of writing, there were no well-known drug interactions with ornithine.
*Athletes and fitness advocates may claim benefits for ornithine based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on ornithine. For more complete and detailed information, including references and safety information, see Ornithine as a nutritional supplement.
1. Bucci L, Hickson JF, Pivarnik JF, et al. Ornithine ingestion and growth hormone release in body-builders. Nutr Res 1990;10:239–45.
2. Gater DR, Gater DA, Uribe JM, et al. Effects of arginine/lysine supplementation and resistance training on glucose tolerance. J Appl Physiol 1992;72:1279–84.
3. Bucci LR, Hickson JF Jr, Wolinsky I, et al. Ornithine supplementation and insulin release in bodybuilders. Int J Sport Nutr 1992;2:287–91.
4. Suminski RR, Robertson RJ, Goss FL, et al. Acute effect of amino acid ingestion and resistance exercise on plasma growth hormone concentration in young men. Int J Sport Nutr 1997;7:48–60.
5. Fogelholm GM, Naveri HK, Kiilavuori KT, et al. Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters. Int J Sport Nutr 1993;3:290–7.
6. Elam RP. Morphological changes in adult males from resistance exercise and amino acid supplementation. J Sports Med Phys Fitness 1988;28:35–9.
7. 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.
Copyright © 2007 Healthnotes, Inc. All rights reserved. www.healthnotes.com
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.
