L-citrulline is an amino acid found in watermelon, pumpkins, and cucumbers. It can also be taken as a supplement to improve athletic performance, increase blood flow, and reduce muscle soreness.
It works by increasing nitric oxide production in the body, which improves circulation and endurance during workouts. L-citrulline has also been studied for its potential to improve erectile dysfunction, reduce high blood pressure, and support cardiovascular health.