In the body, citrulline has several important effects. Vasodilation is one way it works. Vasodilation is the widening of arteries or veins. Lower blood pressure and increased blood flow are associated with it. +
Citrulline is converted to arginine after consumption.
As arginine is converted into nitric oxide, blood vessels are dilated by relaxing smooth muscle cells that constrict them. Consuming citrulline may increase arginine levels more than consuming arginine alone. Arginine and citrulline are processed and absorbed differently by the body. + 
Citrulline supplements may lower blood pressure, especially in people with high blood pressure. Researchers found that citrulline reduced blood pressure by 6–16% after seven days in a small study of 12 adults with normal blood pressure. After exercise, citrulline can increase growth hormone (GH) levels. + 
The performance of endurance exercise is not improved by a single dose of citrulline. Oxygen consumption is not affected by taking supplements for one to two weeks. It can, however, increase the amount of oxygen in muscle tissue. Citrulline malate has been shown to improve weight training performance in several studies. +
Citrulline malate was evaluated in one study on 41 men in order to determine its effects on the ability to perform repetitions during upper body exercises. Citrulline malate increased repetition performance by 53% compared to a placebo. +