Ornithine is a non-proteinogenic amino acid that plays a crucial role in the urea cycle, a process that helps remove ammonia from the body. It is produced from arginine and is essential for the synthesis of polyamines, which are important for cell growth and function. Ornithine is not incorporated into proteins but serves as a precursor for other important compounds. In addition to its role in metabolism, ornithine is sometimes used as a dietary supplement. Some studies suggest it may help improve exercise performance and reduce fatigue. However, more research is needed to fully understand its benefits and potential side effects.