L-Ornithine: Arginine's Overlooked Metabolic Child
Molecular structure of l-ornithine ( HMDB. V2.5 ) Ornithine is an amino acid produced in the urea cycle by the splitting off of urea from arginine. It is a central part of the urea cycle, which allows for the disposal of excess nitrogen. L-Ornithine is also a precursor of citrulline and arginine BUT hardly any of the self-proclaimed supplement gurus know about its proven effects on exercise performance. Almost two years ago, Sugino et.al. ( Sugino. 2008 ) published the results of a study which investigated the effect of 2mg or 6mg l-ornithine supplementation on 120min exercise performance on a cycle ergometer and found that oral L-ornithine administration promoted lipid metabolism and activated the urea cycle from serum triacylglycerol, ketone bodies, free fatty acids, and blood ammonia level changing. L-ornithine significantly attenuated the subjective feeling of fatigue (measured by visual analog scale at postrecovery) compared with postload (P < .01). [...] In the ph...