Designs for Health’s L‑Arginine provides 750 mg of the amino acid, arginine, per capsule. Arginine is an amino acid that supports heart health and helps promote a healthy circulatory system and immune system.* It is a precursor of nitric oxide, a compound known to be important for blood pressure maintenance and healthy endothelial function.* Endothelial cells form a single cell layer that lines all blood vessels and acts as a barrier and regulates exchanges between the bloodstream and the surrounding tissues. Arginine is needed for protein structure and function, but it has additional biological roles, including the support of heart health and immune function and helps maintain normal blood pressure.* As a precursor to nitric oxide, arginine plays an important role in relaxing blood vessels and helping maintain normal blood pressure. Nitric oxide also helps support immune function.* Arginine can be synthesized in the body, which may generate an adequate supply of argninine. However, there are several factors that may cause the body to be unable to synthesize sufficient amounts of arginine, which is why it is considered a conditionally essential amino acid. Certain conditions and populations may increase the need for arginine. Pregnancy, strenuous exercise, trauma, and recovery from surgery may also increase the need for arginine.*