L-Arginine is a naturally occurring amino acid vital for a variety of biochemical reactions in our bodies, and is most notably a precursor of Nitric Oxide. L-Arginine is involved in cell division, immune and cardiovascular functions, and the release of growth hormone, insulin, and other substances. L-Arginine plays an important role in our body's protein metabolism and is therefore essential to a healthy diet.Natrol L-Arginine:- Supports muscle protein synthesis,- Enhances sexual responsiveness,- Supports the health of your blood vessels and circulation,- Supports vasodilation to enhance blood flow,- Maintain heart health.It is also popular among bodybuilder and fitness enthusiast as recent clinical studies show evidence that it can:- Build lean muscle,- Boost HGH production,- Preserve bone density.