L-Arginine is an amino acid best known for its beneficial effect on the vascular system. It is converted to nitric oxide (NO) in vascular endothelial cells and causes vasodilation while also decreasing the potent vasoconstrictor endothelin-1 in the plasma. Aging selectively impairs the endothelium’s dilatory response, which can negatively affect the microvasculature and the organs they supply.

Aadministration of L-arginine has been shown to restore endothelium-dependent vasodilation in those with an impaired response. In addition, L-arginine protects the delicate vessels by acting as a potent antioxidant and reducing the superoxide free radical. Preliminary clinical evidence suggests that L-arginine, along with potent antioxidants, can enhance erectile function.