Amino Acid
Ornithine
SaveA non-protein amino acid that participates in the urea cycle, facilitating ammonia detoxification. Studied for exercise-induced fatigue reduction, sleep quality, and stress hormone modulation.
Quick verdict
Limited but interesting evidence for reducing exercise-related fatigue and improving subjective sleep. Effects are modest.
Evidence score
A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.
What the research shows
Small trials show ornithine supplementation may reduce subjective fatigue during prolonged exercise, likely through enhanced ammonia clearance. A few Japanese studies report improved sleep quality and reduced cortisol. Evidence quality is moderate at best.
Benefits
- May reduce exercise-related fatigue via ammonia clearance
- Preliminary evidence for improved sleep quality
- Potential stress-hormone modulation
Dosage notes
400–2000 mg before exercise or before bed, depending on intended use.
Side effects
- GI distress at high doses
- Diarrhea
Who should be cautious
Generally well tolerated. GI distress possible at high doses. Limited data in pregnancy.
What this page cannot tell you
Most studies are small and many come from a single research group. Replication in larger, diverse populations is needed.
Leaderboard scores
- Recovery40
- Sleep40
- Energy30
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