Citrulline is an amino acid that is converted to L-arginine in the body during the urea cycle, alongside the other amino acid L-ornithine. Supplementing with citrulline is a more effective way to raise arginine levels and enhance nitric oxide (NO) production in the body, rather than supplementing with arginine.

Citrulline can help increase blood flow and nutrients to working muscles, help maintain nitrogen balance in the muscles, increase energy levels, help reduce fatigue and post-workout muscle soreness, and enhance endurance during exercise.