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Amino acids: arginine, lysine, ornithine
Last reviewed: 08.07.2025
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Arginine and ornithine are replaceable amino acids, while lysine is an essential amino acid that must be obtained from food.
Main functions
- Increase muscle mass.
- Reduce the amount of fatty tissue.
- Increase the secretion of growth hormone.
Theoretically, it can be concluded that oral consumption of one amino acid or a combination of them will increase the circulation of growth hormone (GH) and insulin. The advantage of elevated GH and insulin levels is related to their anabolic properties. It is suggested that elevated GH and insulin levels contribute to an increase in muscle mass and a decrease in the amount of fat tissue.
GH concentrations increased at 30, 60, and 90 minutes of exercise, but no differences were observed between groups. At basal levels, acute GH secretion increased after amino acid administration.
Research results
Fogelholm et al. studied the consumption of 2 g of arginine, lysine, and ornithine taken twice daily. Eleven weightlifters were given either the amino acid or placebo, and GH and insulin levels were measured every 24 hours. The peaks in GH levels were not different between the placebo and amino acid supplemented groups, and insulin levels did not increase after supplementation. The researchers concluded that the ergogenic value of low doses of amino acids is questionable.
Because GH levels decline with age, Corpas et al. examined the effects of oral lysine and arginine supplementation on GH in elderly men (69 ± 5 years). Two groups of eight healthy men were given 3 g of arginine and lysine twice daily for 14 days. GH levels were measured in blood samples collected every 20 min from 2 a.m. to 8 a.m. The results showed that both GH and serum insulin levels did not change significantly, suggesting that oral arginine and lysine supplementation is not a means of enhancing GH secretion in elderly men.
Suminski et al. studied the effects of amino acid supplementation and resistance training on plasma GH concentrations in young men. Four sets of studies were conducted on 16 subjects: the first set involved exercise and placebo, the second set involved exercise and amino acid, the third set involved amino acid alone, and the fourth set involved placebo alone.
Recommendations
Studies have shown that supplementation with arginine, lysine, and ornithine does not affect GH levels or body composition. Combining supplementation with exercise does not increase GH levels more than exercise alone.
The rapid expansion of free amino acid supplements has made it possible to consume large amounts of individual amino acids. This is not possible with protein foods or protein supplements, since they contain different amino acids. There are no known problems associated with the consumption of individual amino acids, except for eosinophilia-myalgia syndrome (caused by contaminated tryptophan). However, large doses of some amino acids may interfere with absorption, cause gastrointestinal disturbances, and lead to metabolic imbalances, so it is prudent to avoid large doses of individual amino acids until their safety is proven.
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