Citrulline is a non-essential amino acid that is an important intermediate in the urea cycle, functioning along with Arginine and Ornithine to rid the body of ammonia, a byproduct of protein metabolism.  Because Citrulline is a precursor of Arginine, it provides a readily available source material for Arginine production, which in turn, can be used for the production of Nitric Oxide (NO).  NO plays a fundamental role in vascular function and blood flow.  Citrulline therefore, not only supports detoxification pathways, but also supports NO production and a healthy cardiovascular system.*