Arginine, and L-arginine, are precursors of nitric oxide (NO). NO is a colorless gas. Yet it relaxes the smooth muscle of the arteries. This has been discovered and used for decades. Nitrates and nitrites, like nitroglycerin, have been used to decrease angina. Relaxing the smooth muscles of the veins and arteries decreases the load on the heart. That's how it decreases the pain of angina.

In 1998, the Nobel Prize for medicine went to Drs. Furchgott, Murad, and Ignarro for discoveries leading to understanding nitric oxide.

Arginine and citrulline are metabolic precursors of nitric oxide. There is debate within the supplements community re: which is better. That debate is not covered in this video. Instead, we cover a couple of studies dealing with L-arginine as a supplement.