Overview
Urea cycle amino acid for ammonia clearance.
- Dietary protein from animal sources (meat, fish, eggs, dairy) and plant sources (soy, legumes, grains)
- Free-form amino acid powders and capsules
- Targeted pre-workout, recovery, or sleep formulations
- Free-form crystalline powder
- Capsules or tablets
- Pre-mixed recovery or hydration beverages
- Time-release formulations
Mechanism of action
Substrate for urea cycle; reduces fatigue.
- · Substrate for urea cycle
- · reduces fatigue
Effects on the body
Organ system effects
L-Ornithine supports hepatocyte antioxidant defenses (glutathione, Nrf2) and phase-I/II detoxification.
Evidence-based benefits
Reduces exercise fatigue
Moderate evidencePotential side effects
- · GI upset
Drug interactions
Supplement interactions
- Milk thistle (silymarin)Complementary hepatoprotective antioxidant pathways.
- NACRestores hepatic glutathione.
No specific avoidances listed.
Dosing & bioavailability
Where to buy
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Third-party testedIndependently verified L-Ornithine — look for USP, NSF, or Informed Sport seals on the label for purity and dose accuracy.L-Ornithine third party tested NSF
CapsulesPre-measured L-Ornithine capsules — easiest for travel and consistent daily dosing without scoops or scales.L-Ornithine capsules
PowderBulk unflavored L-Ornithine powder — best cost-per-gram and flexible dosing for stacking or mixing into drinks.L-Ornithine powder unflavored
Best sellersMost-purchased L-Ornithine products on Amazon — a quick way to see what's reviewed widely before you commit.L-Ornithine best sellerScientific evidence8Show studiesHide studies
Ornithine and exercise fatigue
Sugino T, et al.
17 male volunteers
Reduced perceived fatigue during cycling.
PubMed: L-Ornithine — Reduces exercise fatigue
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PubMed: L-Ornithine — randomized controlled trial
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PubMed: L-Ornithine — meta-analysis
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PubMed: L-Ornithine — pharmacokinetics
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PubMed: L-Ornithine — dose response
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Google Scholar: L-Ornithine — clinical evidence
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