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Types of L-Ornithine: Forms & Bioavailability

Evidence:Preliminary
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Forms Comparison

FormBioavailabilityBest For
L-Ornithine HClModerateGeneral supplementation; most common form
L-Ornithine-L-Aspartate (LOLA)ModerateLiver support and hepatic encephalopathy treatment
Ornithine Alpha-Ketoglutarate (OKG)ModerateWound healing and clinical nutrition applications

L-Ornithine HCl

Bioavailability: Moderate. Best for: General supplementation; most common form.

L-Ornithine-L-Aspartate (LOLA)

Bioavailability: Moderate. Best for: Liver support and hepatic encephalopathy treatment.

Ornithine Alpha-Ketoglutarate (OKG)

Bioavailability: Moderate. Best for: Wound healing and clinical nutrition applications.

Full L-Ornithine Guide

References

  1. RCTMiyake M, Kirisako T, Kokubo T, et al. (2014). Randomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers. Nutrition Journal. DOI PubMed
  2. RCTSugino 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. DOI PubMed
  3. Butterworth RF, McPhail MJ. (2019). L-Ornithine L-Aspartate (LOLA) for Hepatic Encephalopathy in Cirrhosis: Results of Randomized Controlled Trials and Meta-Analyses. Drugs. DOI PubMed
  4. Meta-analysisHe Q, Mao C, Chen Z, Zeng Y, et al. (2024). Efficacy of L-ornithine L-aspartate for minimal hepatic encephalopathy in patients with cirrhosis: A meta-analysis of randomized controlled trials.. Arab journal of gastroenterology : the official publication of the Pan-Arab Association of Gastroenterology. DOI PubMed
  5. Meta-analysisButterworth RF (2020). Beneficial effects of L-ornithine L-aspartate for prevention of overt hepatic encephalopathy in patients with cirrhosis: a systematic review with meta-analysis.. Metabolic brain disease. DOI PubMed
  6. Meta-analysisGoh ET, Stokes CS, Sidhu SS, Vilstrup H, et al. (2018). L-ornithine L-aspartate for prevention and treatment of hepatic encephalopathy in people with cirrhosis.. The Cochrane database of systematic reviews. DOI PubMed
  7. Bai M, Yang Z, Qi X, Fan D, et al. (2013). l-ornithine-l-aspartate for hepatic encephalopathy in patients with cirrhosis: a meta-analysis of randomized controlled trials.. Journal of gastroenterology and hepatology. DOI PubMed
Show 5 more references
  1. Jiang Q, Jiang XH, Zheng MH, Chen YP (2009). L-Ornithine-l-aspartate in the management of hepatic encephalopathy: a meta-analysis.. Journal of gastroenterology and hepatology. DOI PubMed
  2. Ismaiel A, Ciornolutchii V, Popa SL, Dumitrascu DL (2026). Can ammonia scavenging treat MASLD? Evaluating the evidence for L-ornithine L-aspartate-A systematic review.. European journal of clinical investigation. DOI PubMed
  3. Yang H, Kuramochi Y, Sato S, Sakai R, et al. (2025). Safety assessment of L-ornithine oral intake in healthy subjects: a systematic review.. Amino acids. DOI PubMed
  4. Zhang H, Fu Y, Lin M, Nan Z, et al. (2025). Efficacy and safety of L-ornithine L-aspartate combined with lactulose in treatment of hepatic encephalopathy: a systematic review and meta-analysis of randomized controlled trial.. Frontiers in medicine. DOI PubMed
  5. Shynkevych VI, Kolomiiets SV, Udaltsova KO, Kaidashev IP (2025). L-ornithine supplementation in periodontitis treatment yields greater benefits than L-arginine after one year: Part II of a randomized controlled pilot study.. Complementary therapies in medicine. DOI PubMed