What Are The Benefits Of L-Ornithine?

Amino acids are known as the building blocks of proteins. 

The latter is made up of several amino acids in a sequence. 

Depending on the sequence, you will have one protein or another. 

Each protein has a code on the DNA depending on its amino acid sequence. But L-Ornithine is not used to create proteins.

This fact makes people wonder: “is ornithine an amino acid?” 

If it is, what are the benefits? Is it necessary for life? 

This article will review what L ornithine is and what it is used for. We will also give you a list of L ornithine benefits and their scientific evidence.

If you are considering buying an ornithine supplement, this article will help you find out when you need it and what it can do for you. 

However, if you plan to use a high dose or want to treat a health condition with ornithine, be sure to talk about it with your doctor before taking the supplement.

What is L-Ornithine?

Ornithine is an amino acid, but it is a different type of amino acid. One that does not form proteins. 

In this regard, it is entirely different from lysine and other essential amino acids. However, it is still important to have it around if you want to stay alive.

Ornithine function is related to liver detoxification and is thought to help with physical performance. 

If you are looking for ornithine supplementation, you will likely find one of these formulations:

  • L-ornithine hydrochloride: It is also known as L-ornithine HCl. It is simply ornithine with an extra hydrogen and chloride atom.
  • Ornithine Alpha-ketoglutarate: This is a more complex supplement. It combines ornithine and gives a more direct raw material for amino acid and nitric oxide synthesis.
  • Arginine and ornithine: These are two amino acids. They are both similar and related to each other. Arginine and ornithine are known to work synergistically. They amplify each other to become more effective.
  • L-ornithine L-aspartate: It is also a combination of two amino acids that complement each other.

What is L-Ornithine used for?

Ornithine supplementation can be used for different conditions and purposes. According to the function you want to trigger, some formulations are more effective than others. 

For instance:

  • L ornithine HCL is mainly used for exercise recovery. It helps reduce physical fatigue and increases muscle performance in athletes and bodybuilders. It may also help with muscle strength (1).
  • Ornithine alpha-ketoglutarate brings L-ornithine benefits further. It is a direct precursor of nitric oxide and arginine. As such, it may help with cardiovascular function and muscle repair. It helps the body increase protein synthesis (2,3).
  • Arginine and ornithine benefit the body in the same way as described above. The difference is that arginine helps the body absorb ornithine. Cells take up more ornithine, and the supplement is now more effective (4).
  • L-ornithine L-aspartate is particularly useful for patients with liver disease. This is the most commonly used combination in patients with hepatic encephalopathy. In these patients, ammonia builds up in the brain, causing neurologic problems. This ornithine supplement is thought to help eliminate waste products (4).

What are the benefits of L-Ornithine?

There are many studies about the benefits of ornithine supplementation. Some are potential benefits with plenty of evidence. Others have fewer studies. 

As you can probably guess, ornithine studies are sometimes difficult to evaluate because there are many formulations. Not all of them have been tried to test the potential benefits.

Still, we can summarize the most critical L-ornithine benefits as follows:

Improvements in athletic performance

This is one of the most popular uses. There are clinical studies on bodybuilders and other athletes. 

The studies show that people recover faster from exercise after taking ornithine—aerobic capacity increases, including muscle strength (5,1). 

One of the most effective combination supplements is L-ornithine L-aspartate, which improves mental sharpness and physical performance.

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Increases the production of growth hormone

This hormone is also helpful in sports. However, injecting growth hormone is banned as doping. 

Ornithine and arginine help your body increase the production of this hormone. However, the dose to achieve a significant increase in growth hormone is very high. 

After consuming such a high dose, it is easier to experience the side effects mentioned below. 

Thus, if you’re looking for this application, talk to your doctor and consume ornithine supplements under supervision (6).

It may improve sleep quality

There is one study on Japanese adults under stress. They had a better sleep quality and reduced their fatigue levels after using ornithine supplements. 

Their mood parameters also improved, reducing hostile and angry behaviors. Interestingly, cortisol levels may also reduce, suggesting that stress levels were reduced (7).

sleep and immune system

It may help patients with hepatic encephalopathy

When the liver fails, this organ stops eliminating a waste product known as ammonia. This and other byproducts accumulate in the body. 

As it builds up in the brain, ammonia then causes mental alterations ranging from memory problems to coma and death. 

In these cases, ornithine supplements can sometimes prevent hepatic encephalopathy. In patients with this condition, it reduces ammonia levels in the blood (8).

It accelerates tissue healing

Ornithine may also help build up new tissue. This includes muscle tissue after strenuous workouts and skin tissue in burns and wounds. Protein breakdown is reduced, and the healing process accelerates. 

A promising study shows burn victims showing improved results after taking this type of supplement. Your doctor should be the one to tell you when to take L-ornithine in such cases (9).

Hangover recovery

This benefit is also very popular but not thoroughly investigated. According to one study, people who take ornithine after consuming alcohol have fewer hangover symptoms

Fatigue levels, confusion, and hostility behaviors are reduced the day after. There are still no studies to clarify how ornithine improves hangover symptoms (10).

Ornithine dosage depends on supplement use. Most studies about athletic performance use doses of 1 gram twice a day. 

Studies about sleep quality and hangover recovery used doses of 400 mg. Higher levels can be warranted if you want to increase growth hormone synthesis.

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Are there any side effects?

L-ornithine side effects depend on the doses. At a low dose, clinical trials rarely report any side effects. Higher doses are typically used to increase growth hormone synthesis and have side effects. 

The most common adverse events associated with ornithine consumption are:

  • Diarrhea
  • Muscle cramps
  • Cough
  • Nausea

Patients with eye disease and genetic health issues may need clearance before using L-ornithine. 

There is a rare disease in visual health known as gyrate atrophy, and these patients can experience retinal damage after long-term consumption of an ornithine supplement.

Similarly, patients with ornithine transcarbamylase deficiency should not consume ornithine supplements. 

These patients lack an important enzyme in the urea cycle. Therefore, their body becomes unable to convert ornithine, and it builds up. 

They should never use this type of supplement and may also need to stay away from foods high in ornithine levels.

Ornithine supplements are not recommended in healthy children, pregnant and lactating women. There are no studies about the risks in these groups. Thus, it should only be used in case of ornithine deficiency.


Ornithine supplementation is a popular choice among bodybuilders and athletes. It is an amino acid, but it is not used to build proteins, unlike essential amino acids. It is used in the urea cycle or as a precursor of other essential molecules.

L ornithine benefits depend on the formulation. For example, ornithine HCl is beneficial to prevent physical fatigue and help athletes recover after a strenuous workout. 

Ornithine alpha-ketoglutarate has been used to speed up tissue healing. L-ornithine L-aspartate has plenty of studies that show it can reduce the symptoms of hepatic encephalopathy. Arginine and ornithine supplementation is used in combination to improve ornithine take-up by cells and tissues. 

Ornithine is a safe supplement to take in low doses. Ornithine side effects are only apparent in a very high dose and include diarrhea, muscle cramps, cough, and nausea.

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  1. Sugino, T., Shirai, T., Kajimoto, Y., & Kajimoto, O. (2008). L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism. Nutrition research, 28(11), 738-743. https://pubmed.ncbi.nlm.nih.gov/19083482/ 
  2. Wernerman, J., Hammarqvist, F. O. L. K. E., von der Decken, A. L. E. X. A. N. D. R. A., & Vinnars, E. R. I. K. (1987). Ornithine-alpha-ketoglutarate improves skeletal muscle protein synthesis as assessed by ribosome analysis and nitrogen use after surgery. Annals of surgery, 206(5), 674. https://pubmed.ncbi.nlm.nih.gov/3118827/ 
  3. Cynober, L. (2004). Ornithine α-ketoglutarate as a potent precursor of arginine and nitric oxide: a new job for an old friend. The Journal of nutrition, 134(10), 2858S-2862S. https://pubmed.ncbi.nlm.nih.gov/15465801/ 
  4. Saavedra-Molina, A., & Pina, E. (1987). Ornithine uptake by rat liver mitochondria: effect of calcium and arginine. Biochemistry International, 15(1), 81-86. https://europepmc.org/article/med/1930251 
  5. Demura, S., Morishita, K., Yamada, T., Yamaji, S., & Komatsu, M. (2011). Effect of L-ornithine hydrochloride ingestion on intermittent maximal anaerobic cycle ergometer performance and fatigue recovery after exercise. European journal of applied physiology, 111(11), 2837-2843. https://pubmed.ncbi.nlm.nih.gov/21431425/ 
  6. Zajac, A., Poprzecki, S., Zebrowska, A., Chalimoniuk, M., & Langfort, J. (2010). 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), 1082-1090. https://pubmed.ncbi.nlm.nih.gov/20300016/ 
  7. Miyake, M., Kirisako, T., Kokubo, T., Miura, Y., Morishita, K., Okamura, H., & Tsuda, A. (2014). Randomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers. Nutrition journal, 13(1), 1-8. https://pubmed.ncbi.nlm.nih.gov/24889392/ 
  8. Hadjihambi, A., Arias, N., Sheikh, M., & Jalan, R. (2018). Hepatic encephalopathy: a critical current review. Hepatology international, 12(1), 135-147. https://pubmed.ncbi.nlm.nih.gov/28770516/ 
  9. De Bandt, J. P., Coudray-Lucas, C., Lioret, N., Lim, S. K., Saizy, R., Giboudeau, J., & Cynober, L. (1998). A randomized controlled trial of the influence of the mode of enteral ornithine α-ketoglutarate administration in burn patients. The Journal of nutrition, 128(3), 563-569. https://pubmed.ncbi.nlm.nih.gov/9482764/ 
  10. Kokubo, T., Ikeshima, E., Kirisako, T., Miura, Y., Horiuchi, M., & Tsuda, A. (2013). A randomized, double-masked, placebo-controlled crossover trial on the effects of L-ornithine on salivary cortisol and feelings of fatigue of flushers the morning after alcohol consumption. BioPsychoSocial Medicine, 7(1), 1-7. https://bpsmedicine.biomedcentral.com/articles/10.1186/1751-0759-7-6 

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