L-arginine and L-ornithine are complementary amino acids involved in the Urea cycle in humans (along with L-Citrulline) and are a popular choice among athletes especially weightlifters and bodybuilders. L-ornithine is primarily used to aid in vasodilation (widening of the blood vessels) and increase muscular performance and growth. L-ornithine is made in the body as well as in laboratory and is also used as a medicine and as a supplement by many bodybuilders. Bodybuilders use ornithine for improving athletic performance.
Growth Hormone Stimulation with L-Ornithine and L-Arginine Combination
It is well-known that growth hormone is essential to gain benefits from training such as increasing muscle mass and strength due to causing anabolic action [1]. Many amino acids have been shown to have growth hormone secretion effect (by intravenous infusion or oral ingestion) [1]. However, ornithine, arginine and lysine and are believed to be superior in stimulating growth hormone secretion than others [2].
We encourage you to read our article about effects of L-arginine on athletic performance and growth hormone secretion.
Zajac, Adam, et al. [3] designed a study to investigate the effect of arginine and ornithine supplementation on serum growth hormone, insulin-like growth factor-1, insulin-like growth factor-binding protein 3 (GH, IGF-1, IGFBP-3), testosterone, cortisol, and insulin levels. During 3-week heavy-resistance training, bodybuilders were randomly divided between L-Arginine / L-ornithine group (n = 9) and the placebo group (n = 8). Fasting blood samples were collected at rest, 2 minutes after the cessation of the training, and after 1 hour of recovery. Both growth hormone and insulin-like growth factor-1 serum levels were significantly increased (p < 0.05) after L-Arginine and L-ornithine supplementation at both time points, whereas a significant decrease in IGFBP-3 protein was seen during the recovery period. There was no between-group difference in the remaining hormone levels.
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To investigate whether L-ornithine L-arginine combination effects total strength, lean body mass and urinary hydroxyproline(UH) Elam, R. P. and colleagues [4] tested twenty-two adult males. They participated in a 5-week progressive strength training program. Eleven subjects received the amino acids L-arginine and L-ornithine and the other half, a placebo. The results showed that subjects who were taking the combination scored significantly higher in total strength and lean body mass (p < 0.05), and significantly lower in UH (p less than.05), compared to placebo. It was later noted that statistical analyses in this study were seriously flawed and inappropriate [5].
Effects of L-Ornithine Ingestion on Human Growth Hormone
Chromiak and assistants [2] have examined the effect of L-ornithine hydrochloride ingestion on serum growth hormone secretion response after strength training in young untrained men. Results show significantly increased blood growth hormone levels after strength training by L-ornithine hydrochloride ingestion. This study was funded by Kyowa Hakko Bio Co., Ltd, the company that produces this kind of amino acids plus the study design lacked randomization. In 1990 Bucci et al. [7] also reported a significant increase in serum growth hormone levels 45 and 90 minutes after bodybuilders ingested 170 mg/kg of L-ornithine hydrochloride. Demura and colleagues [1] examined the effects of ornithine HCl ingestion before resistance exercise on postexercise growth hormone secretion and reported greater blood growth hormone concentrations after resistance exercise in subjects that ingested ornithine HCl compared to placebo group.
One small study by Lambert and colleagues [8] reported that growth hormone concentrations were not altered consistently in healthy young males following the ingestion of 1.85-g ornithine/tyrosine supplement. Serum growth hormone concentration was also unaffected with somewhat lower dose 100 mg/kg of ornithine HCl during submaximal endurance exercise [9].
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Keep in Mind…
The use of specific amino acids to induce growth hormone release may not be very effective in strength-trained individuals consuming high-protein diets. Diets high in protein apparently increase basal growth hormone levels [6].
L-Ornithine Side Effects
A Bucci et al. [7] study reported that six out of ten subjects complained of gastrointestinal discomforts such as stomach ache and diarrhea.
(Other common names: Chlorhydrate d’Ornithine, L-Ornithine, L-Ornithine HCl, L-Ornithine Hydrochloride, L-5-aminorvaline, L-2,5-diaminovaleric acid, Ornitina, Ornithine)
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References
- Demura, Shinichi, et al. “The effect of L-ornithine hydrochloride ingestion on human growth hormone secretion after strength training.” (2010).
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Chromiak, Joseph A., and Jose Antonio. “Use of amino acids as growth hormone-releasing agents by athletes.” Nutrition 18.7 (2002): 657-661.
- Zajac, Adam, et al. “Arginine and ornithine supplementation increases growth hormone and insulin-like growth factor-1 serum levels after heavy-resistance exercise in strength-trained athletes.” The Journal of Strength & Conditioning Research 24.4 (2010): 1082.
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Elam, R. P., et al. “Effects of arginine and ornithine on strength, lean body mass and urinary hydroxyproline in adult males.” J Sports Med Phys Fitness 29.1 (1989): 52-6.
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Chromiak, Joseph A., and Jose Antonio. “Use of amino acids as growth hormone-releasing agents by athletes.” Nutrition 18.7 (2002): 657-661.
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Sellini, M., et al. “Behavior of basal values and circadian rhythm of ACTH, cortisol, PRL, and GH in a high-protein diet.” Boll Soc Ital Biol Sper 57 (1981): 963.
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Bucci, Luke, et al. “Ornithine ingestion and growth hormone release in bodybuilders.” Nutrition Research 10.3 (1990): 239-245.
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Lambert, M. I., et al. “Failure of commercial oral amino acid supplements to increase serum growth hormone concentrations in male body-builders.” International Journal of Sport Nutrition 3.3 (1993): 298-305.
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Demura, Shinichi, et al. “L-ornithine hydrochloride ingestion increased carbohydrate oxidation but not lipid oxidation during submaximal endurance exercise following resistance exercise.” Advances in Bioscience and Biotechnology 4 (2013): 81.
