L-Ornithine
Accelerates ammonia clearance through the urea cycle, reducing exercise-induced fatigue and supporting recovery during prolonged efforts.
L-Ornithine is a non-protein amino acid that plays a central role in the urea cycle, helping the body eliminate ammonia. During intense or prolonged exercise, ammonia accumulates and contributes to fatigue. Ornithine supplementation may help clear ammonia more efficiently, reducing fatigue and supporting recovery. It's often combined with arginine for synergistic effects on growth hormone and exercise performance.
Accelerates ammonia detoxification
Helps clear exercise-induced ammonia buildup
May stimulate GH release when combined with arginine
How Ornithine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
2-6g daily
Loading: Not required
Take with food
| Form | Type |
|---|---|
| 💊L-Ornithine HCl | Recommended |
| 💊L-Ornithine capsules | Alternative |
| 💊OKG (Ornithine Alpha-Ketoglutarate) | Alternative |
Often sold in combination with arginine. OKG may have enhanced effects.
Minimum: 2 weeks
Optimal: 8 weeks
Cycling: Not required
Note: Can be combined with arginine. For sleep benefits, take 30-60 minutes before bed.
Less ammonia-related exhaustion during exercise
Improved recovery between training sessions
May enhance sleep, especially after stress or exercise
May cause digestive upset at high doses
Limited data; consult healthcare provider
May benefit those with high ammonia production
Tip: Take with food; reduce dose
Tip: Reduce dose; divide into smaller doses
Top studies from 38+ peer-reviewed papers
Langer G et al. • The Cochrane database of systematic reviews (2024)
“The benefits of nutritional interventions with various compositions for pressure ulcer prevention and treatment are uncertain.”
Ramanathan G et al. • Metabolomics : Official journal of the Metabolomic Society (2025)
“These identified metabolites hold potential as early markers for T2D-induced DKD.”
Zinellu A et al. • Cells (2023)
“Our study suggests that the presence of significant alterations in metabolites within the arginine, transsulfuration, and folic acid pathways can be useful for assessing nitric oxide dysregulation and oxidative stress and identifying novel treatment targets in COPD. (PROSPERO registration number: CRD42023448036.).”
Pulik K et al. • Cells (2023)
“Metabolomics, by searching for biomarkers and distinguishing metabolic pathways, can allow us to understand the pathophysiology of COPD and the development of its phenotypes.”
Onoja A et al. • International journal of molecular sciences (2023)
“Whilst the studies reviewed here were small and may be subject to confounders, it is desirable that biomarker panels be resilient across cohorts if they are to find use in the clinic, highlighting the importance of assessing the robustness and reproducibility of metabolomics analyses in independent populations.”
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