L-Ornithine: Benefits, Dosing, Where To Buy, And More!

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Key Information

L-ornithine lowers stress and anxiety:

L-ornithine can modulate the GABA system, lower cortisol levels, and attenuate the stress response.

L-ornithine improves sleep quality and satisfaction:

L-ornithine can increase melatonin production, promote non-REM sleep, and release growth hormones.

L-ornithine enhances physical performance and endurance:

L-ornithine can buffer ammonia, promote fat metabolism, and reduce fatigue during exercise.

L-ornithine boosts mood and well-being:

L-ornithine can improve feelings of well-being, especially in stressful situations, and may affect serotonin and dopamine levels.

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L-ornithine is a remarkable amino acid that has been gaining attention in the world of nootropics for its potential to enhance brain health, improve sleep quality, and support overall cognitive function. At Holisticnootropics.com, we are dedicated to exploring evidence-based, nutrition-first strategies to optimize mental performance and well-being.

This comprehensive guide will explore the science behind L-ornithine, its mechanisms of action, potential benefits, dosage recommendations, and how it fits into a holistic approach to cognitive enhancement.

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What is L-Ornithine?

L-ornithine is a non-proteinogenic amino acid, meaning it is not used to build proteins in the body. Instead, it plays a crucial role in the urea cycle, a process that helps remove excess nitrogen from the body in the form of urea. L-Ornithine was first discovered in the late 19th century by the German chemist Albrecht Kossel, who isolated it from bird droppings, hence the name “ornithine” derived from the Greek word for bird, “ornis” [1].

Learn More: What are Nootropics? The Ultimate Beginners Guide To Cognitive Enhancers

How L-Ornithine Works in the Body

L-ornithine’s primary function is its involvement in the urea cycle, a series of biochemical reactions in the liver to detoxify ammonia, a toxic byproduct of protein metabolism. By converting ammonia into urea, which can be safely excreted through urine, L-Ornithine helps maintain a healthy nitrogen balance[2].

In addition to its role in the urea cycle, L-Ornithine serves as a precursor for several important compounds:

  • Glutamic acid: An excitatory neurotransmitter involved in learning and memory
  • Proline: An amino acid essential for collagen synthesis and wound healing
  • Citrulline: Another amino acid that participates in the urea cycle and nitric oxide production

L-ornithine also influences key neurotransmitters in the brain, particularly gamma-aminobutyric acid (GABA) and glutamate. By modulating the balance between these neurotransmitters, L-Ornithine may help promote relaxation, reduce stress, and support cognitive function [3].

Learn More: Glutamate: The Good, Bad, And Ugly Neurotransmitter

Benefits of L-Ornithine

Research has uncovered several potential benefits of L-ornithine supplementation for brain health and cognitive performance:

Stress and Anxiety Reduction

L-ornithine has been shown to modulate the GABA system, which promotes relaxation and reduces stress. By enhancing GABA activity, L-Ornithine may help alleviate anxiety and promote a sense of calm. Additionally, L-ornithine has been found to lower cortisol levels, the primary stress hormone in the body [4].

Improved Sleep Quality

Several studies have investigated the effects of L-ornithine on sleep quality. In a randomized, double-blind, placebo-controlled trial, participants who took L-ornithine before bed reported reduced fatigue, decreased feelings of hostility, and increased feelings of refreshment upon waking [4].

Enhanced Athletic Performance

L-ornithine has been studied for its potential to improve athletic performance by reducing ammonia and lactic acid buildup during exercise. In a study on healthy volunteers, L-ornithine supplementation attenuates physical fatigue and promotes lipid metabolism, suggesting its potential as an ergogenic aid [5].

Liver Health Support

Given its role in the urea cycle, L-Ornithine has been investigated for its potential to support liver health by helping detoxify ammonia and protect against liver damage. In animal studies, L-ornithine supplementation has shown promise in reducing markers of liver injury and improving liver function [6].

Cognitive Benefits

Although more research is needed, some studies suggest that L-Ornithine may offer cognitive benefits, such as improved focus, mental clarity, and reduced brain fog. These effects may be attributed to L-Ornithine’s influence on neurotransmitter balance and its ability to reduce ammonia levels in the brain [7].

L-Ornithine Dosage and Forms

The typical dosage range for L-ornithine is between 2 and 6 grams per day, usually divided into two or three doses. To maximize absorption and effectiveness, it is generally recommended to take L-ornithine on an empty stomach, either in the morning or before bed.

L-ornithine is available in several forms, including:

  • L-Ornithine HCl: The hydrochloride salt of L-Ornithine, which is highly water-soluble and well-absorbed
  • L-Ornithine Aspartate (LOLA): A combination of L-Ornithine and aspartic acid, often used for liver health support
  • L-Ornithine Alpha-Ketoglutarate (OKG): A salt formed by combining L-Ornithine with alpha-ketoglutarate, which may offer additional benefits for muscle growth and recovery

L-ornithine is often stacked with other supplements to enhance its effects, such as:

  • Arginine: An amino acid that works synergistically with L-Ornithine to support nitric oxide production and growth hormone release
  • Citrulline: Another amino acid involved in the urea cycle and nitric oxide metabolism, which may complement L-Ornithine’s effects

Learn More: The Best Nootropic Stack For Ultimate Brain Performance

Potential Side Effects and Interactions

L-ornithine is generally well-tolerated, with few reported side effects. However, some individuals may experience gastrointestinal discomfort, such as nausea or diarrhea, especially at higher doses. It is essential to start with a lower dose and gradually increase as tolerated.

Caution should be exercised in individuals with certain genetic conditions, such as hyperammonemia or gyrate atrophy, as L-ornithine supplementation may exacerbate these conditions. Additionally, L-ornithine may interact with certain medications, particularly those affecting liver function or amino acid metabolism. As with any supplement, it is always best to consult with a healthcare professional before starting L-ornithine supplementation.

Natural Sources of L-Ornithine

While L-Ornithine is not abundant in many foods, some natural sources include:

  • Animal protein: Meat, fish, and eggs contain small amounts of L-ornithine
  • Nuts and seeds: Pumpkin seeds, peanuts, and almonds are sources of L-ornithine
  • Grains and legumes: Soybeans, lentils, and wheat germ contain L-ornithine

L-Ornithine vs Other Amino Acids

Amino AcidKey FunctionsTypical Dose
L-OrnithineUrea cycle, precursor to glutamic acid, proline, citrulline2-6 g/day
L-ArginineNitric oxide production, growth hormone release2-5 g/day
L-CitrullineUrea cycle, nitric oxide production3-6 g/day
L-GlutamineProtein synthesis, intestinal health, immune function5-15 g/day

Learn More: L-Glutamine: Benefits, Dosing, Where To Buy, And More!

FAQ about L-Ornithine

Where to Buy L-Ornithine

When shopping for L-Ornithine supplements, it is essential to choose a reputable brand that adheres to strict quality control standards. Look for products that are third-party tested for purity and potency, and free from unnecessary fillers or additives.

Some trusted brands that offer high-quality L-Ornithine supplements include:

L-Ornithine by NOW #1

L-Ornithine by NOW

Say goodbye to stress and sleepless nights

L-Ornithine supplements can be purchased online through various health and wellness retailers, as well as in select brick-and-mortar stores specializing in natural health products. When in doubt, consult with a healthcare professional or a trusted supplement specialist to find the best L-Ornithine product for your needs.

Learn More: Magnesium Breakthrough Review + Discount Code

L-Ornithine Discussions on Reddit

L-Ornithine for Sleep and Relaxation

Many Reddit users report positive experiences with L-Ornithine for improving sleep quality and promoting relaxation:

Hope it works for you! I take 1g of Now brand before bed. Usually dont leave reviews unless Im very happy or very upset and I am very impressed with this product. Just got done with my first workout using this and wow. The pump was insane. I dont usually use pre workout sups and this is the first one Ive used in many years.

u/Interesting-Dig-8651 in discussion ‘Exhausted after l-ornithine HCL?’

L-Ornithine for Ammonia Detoxification

L-Ornithine is often discussed as a potent ammonia scavenger, helping to remove excess ammonia from the brain and body:

Like immediately. And I dont say this lightly. Ive been on psychiatric meds of all kinds, spent a life savings on supplements, but nothing ever gave me a immediate relief from that feeling when your brain is on fire, you are wired but tired, cant focus, procrastinating for days… I guess L-ornithine works really fast to get ammonia out of the brain at least.

u/vanyab25 in discussion ‘L Ornithine for lowering Ammonia’

L-Ornithine Dosage and Timing

Reddit users share insights on optimal L-Ornithine dosage and timing for various effects:

1 suggested serving really makes a positive difference in my workout regimen.

u/imBoo69 in discussion ‘L Ornithine? Anyone taking?’


L-Ornithine is a promising nootropic amino acid with a wide range of potential benefits for brain health, sleep quality, stress reduction, and athletic performance. By supporting the urea cycle, modulating neurotransmitter balance, and influencing key physiological processes, L-Ornithine may help optimize cognitive function and overall well-being.

As with any supplement, it is crucial to approach L-Ornithine use with caution and to consult with a healthcare professional before starting a new regimen. By staying informed, listening to your body, and taking a holistic approach to brain health, you can harness the potential of L-Ornithine to support your cognitive performance and mental well-being.

At Holisticnootropics.com, we are committed to providing our readers with the most up-to-date, science-backed information on nootropics and brain health strategies. Stay tuned for more in-depth articles, engaging podcasts, and expert insights designed to help you optimize your cognitive function and live your best life.

Learn More: 11 Best Nootropics For Brain Fog


  1. Wu G. Amino acids: metabolism, functions, and nutrition. Amino Acids. 2009 May;37(1):1-17. doi: 10.1007/s00726-009-0269-0. https://pubmed.ncbi.nlm.nih.gov/19301095/
  2. Morris SM Jr. Regulation of enzymes of the urea cycle and arginine metabolism. Annu Rev Nutr. 2002;22:87-105. doi: 10.1146/annurev.nutr.22.110801.140547. https://pubmed.ncbi.nlm.nih.gov/12055339/
  3. Kurata K, Nagasawa M, Tomonaga S, Aoki M, Morishita K, Denbow DM, Furuse M. Orally administered L-ornithine reduces restraint stress-induced activation of the hypothalamic-pituitary-adrenal axis in mice. Neurosci Lett. 2012 Jan 11;506(2):287-91. doi: 10.1016/j.neulet.2011.11.024. https://pubmed.ncbi.nlm.nih.gov/22133808/
  4. Miyake M, Kirisako T, Kokubo T, Miura Y, Morishita K, Okamura H, Tsuda A. Randomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers. Nutr J. 2014 Jun 3;13:53. doi: 10.1186/1475-2891-13-53. https://pubmed.ncbi.nlm.nih.gov/24889392/
  5. Sugino T, Shirai T, Kajimoto Y, Kajimoto O. L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism. Nutr Res. 2008 Nov;28(11):738-43. doi: 10.1016/j.nutres.2008.08.008. https://pubmed.ncbi.nlm.nih.gov/19083482/
  6. Staedt U, Leweling H, Gladisch R, Kortsik C, Hagmüller E, Holm E. Effects of ornithine aspartate on plasma ammonia and plasma amino acids in patients with cirrhosis. A double-blind, randomized study using a four-fold crossover design. J Hepatol. 1993 Nov;19(3):424-30. doi: 10.1016/s0168-8278(05)80553-7. https://pubmed.ncbi.nlm.nih.gov/8151104/
  7. Kurata K, Nagasawa M, Tomonaga S, Aoki M, Akiduki S, Morishita K, Denbow DM, Furuse M. Orally administered L-ornithine elevates brain L-ornithine levels and has an anxiolytic-like effect in mice. Nutr Neurosci. 2013 Nov;16(6):255-61. doi: 10.1179/1476830512Y.0000000036. https://catalog.lib.kyushu-u.ac.jp/opac_download_md/27291/48_furuse.pdf

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Erik Abramowitz is a certified Nutritional Therapy Practitioner (NTP), Naturopathic Doctoral student, health coach, and father. He is the primary content creator for HolisticNootropics.com and the host of the Holistic Nootropics Podcast.