L-Arginine is a necessary amino acid for the body to make proteins. L-Arginine is found in red meat, poultry, fish, and dairy products. Once consumed, L-Arginine changes into nitric oxide. Nitric oxide is a powerful neurotransmitter that may help blood vessels relax, improving circulation. It may support cardiovascular health by improving blood flow in the arteries of the heart. L-Arginine helps the body get rid of waste, supporting healthy kidney function, immune function, and repair.