Arginine is a Conditionally Essential Amino Acid involved primarily in urea metabolism and excretion, as well as in DNA synthesis and protein production. Description Ingredients How to Use NOW L-Arginine comes in 500 mg veg capsules and is non-GMO. Arginine is a conditionally essential basic amino acid involved primarily in urea metabolism and excretion, as well as in DNA synthesis and protein production. * It is an important precursor of nitric oxide (NO) and thus plays a role in the dilation of blood vessels. * The L-Arginine used in this product is pharmaceutical grade. Natural color variation may occur in this product. Hypromellose (cellulose capsule), Stearic acid (vegetable source) and Silicon dioxide. Take 2 capsules twice daily as needed. Take between meals or at bedtime with at least 8 oz. of water or juice to facilitate absorption.