L-Arginine is a semi-essential amino acid which is a precursor to nitric oxide, meaning that the body converts L-Arginine into Nitric Oxide gas.  Nitric Oxide is then used by the body to do many different things.  In fact, the discovery of the Nitric Oxide Pathway was awarded the Nobel Prize in Medicine in 1998.  Nobel Prize Winning Research In 1998, three American doctors were able to demonstrate that the body uses Nitric Oxide gas to make blood vessels relax, elastic and dilated, a significant finding in the race to find new ways to improve and support cardiovascular health. What Is Nitric Oxide? Over 20,000 articles in the medical literature since 1980 attest that “absolutely everything in the body depends on it.” Its function in human physiology is so important that the American Academy of Science named Nitric Oxide the “Molecule of the year” in 1992. The Nobel Prize in Medicine was awarded to scientists who began the research on Nitric Oxide in 1998 and now NO has been referred to as “The Molecule of the Millennium.” “It [Nitric Oxide] does everything, everywhere. You cannot name a major cellular response or physiological effect in which [Nitric Oxide] is not implicated today. It’s involved in complex behavioral changes in the brain, airway relaxation, beating of the heart, dilation of blood vessels, regulation of intestinal movement, function of blood cells, the immune system, even how fingers and arms move.” -Dr. Jonathan S. Stamler, Professor of Medicine at Duke University Medical Center.  There are three types of Nitric Oxide (NO): Endothelial-derived NO Brain-Derived NO Macrophage-Derived NO Endothelial-derived NO diffuses out of endothelial cells (cells lining arteries and veins) and into smooth muscle cells of arteries enhancing relaxation and other properties of vascular physiology. Endothelial-derived NO also functions in platelets (blood cells responsible for blood clots) to inhibit aggregation or blood clotting. Brain-derived NO affects several typ