Citrulline vs. Arginine Which One's Better for Vasodilation? @moreplatesmoredates A lot of pre workouts still include Arginine under the assumption that since it's the direct precursor to nitric oxide, it must be GNC L Arginine & L Citrulline 500 mg 500 mg 120 Caplets (120 Servings) GNC L citrulline is an intermediate in the urea and nitric oxide cycles. Download Scientific Diagram L Citrulline vs L Arginine: The Right Amino Acid for Formula L Arginine L Citrulline 500 250 Bestvite.com The Most Trusted Name in Vitamins