L-Ornithine

What it is

L-ornithine is a non-protein amino acid that participates in the urea cycle, the pathway the body uses to clear ammonia produced during protein metabolism and intense exercise. Because rising ammonia is linked to fatigue, ornithine is studied as an anti-fatigue and recovery aid.

Benefits

Doses around 2-6 g have reduced subjective fatigue and, in one trial, improved short-burst anaerobic performance. Effects on blood ammonia and overall performance are inconsistent across studies.

When to take it

Take before or around exercise, often split into divided doses. Some protocols also use it before sleep for recovery.

Side effects

Generally well tolerated; higher doses may cause gastrointestinal upset such as cramping or loose stools. Limited long-term safety data.

Sources

• Sugino et al. (2008), Effect of L-ornithine hydrochloride ingestion on intermittent maximal anaerobic cycle ergometer performance and fatigue recovery
• Acute and chronic ornithine supplementation on exercise-induced ammonia accumulation and cycling performance (PMC12528257)

Products containing L-Ornithine

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