Learn More About L-Ornithine
What is l-ornithine?
L-ornithine (also called 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).
Animal research has suggested that ornithine, along with arginine, may promote muscle-building activity in the body by increasing levels of growth-promoting (anabolic) hormones such as insulin and growth hormone. However, most human research does not support these claims at reasonable intake levels.1 2 3 One study that did demonstrate increased growth hormone with oral ornithine used very high amounts (an average of 13 grams per day) and reported many gastrointestinal side effects.4 One controlled study reported greater increases in lean body mass and strength after five weeks of intensive strength training in athletes taking 1 gram per day each of arginine and ornithine compared with a group doing the exercise but taking a placebo.5 These findings require independent confirmation.
In clinical studies on people hospitalized for surgery, generalized infections, cancer, trauma, or burns, supplementation with ornithine alpha-ketoglutarate (OKG) has been reported to produce several beneficial effects.6 A double-blind trial evaluated the effects of OKG supplementation in elderly people recovering from acute illnesses.7 Those who took 10 grams of OKG per day for two months had marked improvement in appetite, weight gain, and quality of life compared with those taking the placebo. They also had shorter recovery periods and required fewer home visits by physicians and nurses and needed fewer medications.
Ornithine aspartate has been shown to be beneficial in people with brain abnormalities (hepatic encephalopathy) due to liver cirrhosis. In a double-blind trial, people with cirrhosis and hepatic encephalopathy received either 18 grams per day of L-ornithine-L-aspartate or a placebo for two weeks.8 Those taking the ornithine had significant improvements in liver function and blood tests compared with those taking the placebo.
Preliminary9 and controlled10 studies of people with severe burnsshowed that supplementation with 10–30 grams of ornithine alpha-ketoglutarate per day significantly improved wound healing and decreased the length of hospital stays.
Where is l-ornithine found?
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.
Who is likely to be deficient?
Since ornithine is produced by the body, a deficiency of this nonessential amino acid is unlikely, though depletion can occur during growth or pregnancy, and after severe trauma or malnutrition.11 4
How much l-ornithine is usually taken?
In human research involving ornithine, 5–10 grams are typically used per day, sometimes combined with arginine.
Are there any side effects of l-ornithine?
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.
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2. 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.
3. Lambert MI, Hefer JA, Millar RP, et al. Failure of commercial oral amino acid supplements to increase serum growth hormone concentrations in male body-builders. Int J Sport Nutr 1993;3:298–305.
4. Bucci L, Hickson JF, Pivarnik JM, et al. Ornithine ingestion and growth hormone release in bodybuilders. Nutr Res 1990;10:239–45.
5. 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.
6. Cynober L. place des nouveaux substrats azotés en nutrition artificielle périopératoire de l’adulte. Nutr Clin Métabole 1995;9:113 [in French].
7. 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.
8. Stauch S, Kircheis G, Adler G, et al. Oral L-ornithine-L-aspartate therapy of chronic hepatic encephalopathy: results of a placebo-controlled double-blind study. J Hepatol 1998;28:856–64.
9. Cynober L. Amino acid metabolism in thermal burns. JPEN J Parenter Enteral Nutr 1989;13:196–205.
10. 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.
11. Zieve L. Conditional deficiencies of ornithine or arginine. J Am Coll Nutr 1986;5:167–76. [review]
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