From the desk of Dr. Nancy Collins, PhD, RDN, LD, NWCC, FAND You may have noticed that one of the major ingredients in Expedite™ is the amino acid citrulline. While you probably are familiar with arginine, you might not be as familiar with citrulline. Citrulline is a nonessential amino acid, meaning the body can synthesize it endogenously. The function of citrulline is to ...