Now Foods L-Arginine, Double Strength 1000 mgL Arginine is 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. FEATURES: Double StrengthAmino AcidConditionally Essential Amino AcidNitric Oxide PrecursorNon GMOKosherAmino AcidsGMP Quality AssuredThe L Arginine used in this product is Pharmaceutical