Arginine, also called L-arginine, is an amino acid used by the body as a protein building block. It’s also an intermediate metabolite in the urea cycle and the nitric oxide cycle.[1][2][3] The urea cycle removes excess ammonia, a toxic molecule, from the body, and the nitric oxide cycle produces nitric oxide, which is an important signaling molecule involved in vascular function.[1][2][3] Although the body can synthesize arginine, arginine can also be obtained in the diet through protein-containing foods or dietary supplements.[1][2][3]
What is arginine?
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•Last Updated: May 16, 2025
Arginine, or L-arginine, is an amino acid that serves as a protein building block and plays a role in the urea and nitric oxide cycles, which help remove toxic ammonia and produce nitric oxide for vascular signaling. It can be synthesized by the body or obtained from protein-rich foods and dietary supplements.