L-Arginine is a popular amino acid for its amazing nitrogen retention ability.* Nitrogen as you are all aware is one of the key elements in muscle protein synthesis. Some plants can absorb nitrogen, but we mammals have to make do with the stuff we make ourselves. Arginine is mostly present in protanines and histones, two proteins commonly associated with nucleic acids (like DNA and RNA).

L-Arginine is a conditionally essential basic amino acid involved primarily in urea metabolism and excretion as well as DNA synthesis. NOW's L-Arginine 1000 has double that of what other supplements on the market provide to be used as a dietary supplement.