Citrulline is one of the three dietary amino acids in the urea cycle (the other two are L-arginine and L-ornithine). Taking citrulline increases plasma levels of arginine and improves the ammonia recycling process and nitric oxide metabolism. Consequently, citrulline may be useful in situations in which nitric oxide is relevant, such as athletic performance, vascular health, and erectile dysfunction. There are very few foods that have useful amounts of citrulline, but watermelon is a notable exception. The two most common forms of citrulline are L-citrulline and citrulline malate.
What is citrulline?
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•Last Updated: May 16, 2025
Citrulline is a dietary amino acid that is involved in the urea cycle; it increases plasma arginine levels and enhances ammonia recycling and nitric oxide metabolism. It may benefit athletic performance, vascular health, and erectile dysfunction, and watermelon is a notable food source.