Ornithine is a non-proteinogenic amino acid that plays a role in the body mainly in the so-called urea cycle, a metabolic pathway through which excess nitrogen from protein breakdown is disposed of. Unlike many other amino acids, ornithine is not built into body protein but takes part in metabolism itself.
The body can make ornithine itself from the amino acid arginine, which is why it is not considered essential. Ornithine occurs in food only in small amounts, and isolated ornithine supplements are offered mainly in the area of sports nutrition.
Relevance for nutrition and sport
In sport, ornithine is occasionally discussed in connection with recovery and the breakdown of ammonia after intense exertion, as it is involved in the urea cycle. The scientific evidence for targeted ornithine supplementation is thin overall and does not allow reliable statements about a measurable training effect.
For most physically active people, a separate intake of ornithine is not necessary, as the body can produce it from other amino acids. The page amino acids offers a broader overview of amino acids in the context of nutrition and sport. Anyone who eats a balanced, protein-rich diet does not usually need to give their ornithine status any special thought.
