Urea-cycle amino acid supplement · Fact sheet
L-ornithine
Also known as Ornithine
L-ornithine is a non-protein amino acid studied for stress and sleep. A small worker study reported subjective sleep and cortisol changes, but it does not establish an insomnia treatment or growth-hormone enhancement regimen.
What is L-ornithine?
Ornithine participates in the urea cycle. Its metabolic role is not proof of additional benefit from supplementation.
L-ornithine and L-ornithine L-aspartate used in liver-related research are different preparations.
Benefits & claims
Interest in L-ornithine spans cognition and sleep, recovery. Study findings apply to the named formulation and population.
What the evidence supports
- The worker trial found lower cortisol-related measures and improved perceived sleep quality.
- The circadian study reported a 15-minute delay in dim-light melatonin onset, not proof of better clinical sleep.
- These studies do not establish treatment of chronic insomnia or meaningful muscle-growth effects.
Research areas
- Formulation-specific human outcomes
- Mechanistic research
Dosage & frequency
Human study contextThis is an exposure from a named human study, not a generally established treatment or enhancement regimen.
Worker stress and sleep randomized study
52 apparently healthy Japanese adults reporting slight stress and fatigue
- Amount
- 400 mg total daily
- Frequency
- Daily for eight weeks
- Route studied or labeled
- Oral
This was not a chronic-insomnia trial and did not establish a growth-hormone or recovery regimen. The measured cortisol changes are not proof of broad health improvement.
How to read these amounts
An approved regimen belongs to a specific product, indication, and population. A study regimen describes what researchers tested; it does not establish a prescription or a safe self-use protocol. Products, routes, and formulations are not interchangeable. A prescriber uses the full label and individual clinical circumstances.
Personal accounts may describe amounts, schedules and outcomes beyond clinical research. They do not establish a regimen. Read the reported experiences
Formulations, interactions & practical context
- Identity and pharmacology
- Ornithine participates in the urea cycle. Its metabolic role is not proof of additional benefit from supplementation.
Formulation differences
- L-ornithine and L-ornithine L-aspartate used in liver-related research are different preparations.
Interactions & precautions
- The reviewed sources do not establish a comprehensive human interaction profile for this exact substance or combination.
What is still unresolved
- Reproducibility in larger independent trials
- Long-term outcomes and adverse effects
- Equivalence of different preparations and interaction profiles
Side effects & risks
- Small selected-population studies cannot characterize rare harms or safety in severe liver or kidney disease.
- Other ornithine salts and combination supplements need their own interaction and tolerability assessment.
This is a summary of the cited evidence, not a complete product label. A lack of human safety data does not establish safety.
Clinical research
Early human evidenceA 52-person eight-week trial reported stress-marker and subjective sleep effects. A separate 28-person study found a small change in a circadian-phase marker.
Studies
52 Japanese workers; stress and sleep questionnaires over eight weeks.
28 adults; short crossover circadian-phase study.
Personal experiences
Reports describe what someone noticed. They cannot establish cause, typical results, or how often a side effect happens. Amounts and schedules describe the individual account, not an effective or safe dose. Product identity and strength may be unverified, and missing details are left explicit.
No attributable personal accounts were found in the sources reviewed.
Approval status
No FDA-approved L-ornithine drug indication is established for the supplement uses discussed here. Supplement availability is not FDA approval of efficacy or safety.
No FDA-approved product for this entry
Approval covers the labeled product, use and population. A trial phase does not establish success; a stopped program is not ongoing research.
Open questions
- Reproducibility in larger independent trials
- Long-term outcomes and adverse effects
- Equivalence of different preparations and interaction profiles
Summary
These studies do not establish treatment of chronic insomnia or meaningful muscle-growth effects.
Sources
Medical evidence and regulatory sources are listed here. Personal reports are linked separately in the experiences section.
- pubmedRandomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers.
52 Japanese workers; stress and sleep questionnaires over eight weeks.
- pubmedA randomized, double-blind and placebo-controlled crossover trial on the effect of l-ornithine ingestion on the human circadian clock.
28 adults; short crossover circadian-phase study.
- fdaFDA: what approval means for supplements
Dietary supplements are not approved by FDA for safety and effectiveness before marketing.