L-Arginine, an amino acid that helps the body produce nitric oxide in the lining of the arteries. The nitric oxide relaxes the arteries, making them more elastic and flexible, thus allowing more efficient blood flow resulting in the lower blood pressure. Healthy Origins L-Arginine –SR is a unique formulation that utilizes a sustained release delivery system specifically manufactured to release the L-Arginine continuously over a 5-7 hour period. This is a vegetarian formulation.