Arginine + Citrulline is AN optimal combination of two amino acids, which works well as a nitrogen booster. As the research shows, there is a strong synergy between the two amino acids, so when combined together have much better effects than taken separately.
Preparations with arginine and citrulline support the improvement of exercise capacity, reduce the feeling of fatigue, and when combined with resistance training they may also contribute to the enhancement of muscle protein synthesis. They also bring a desired by many athletes effect of enlarging the muscle girth, colloquially called "muscle pump". They can be also used for health-promoting purposes – they work well in the prevention of hypertension, cardiovascular disease, and sexual dysfunctions.
Supplements based on arginine and citrulline work by increasing the production of nitric oxide (NO) and increasing its half-life in the body. The key substrate for the production of NO is arginine. Unfortunately, it is sensitive to the activity of arginase enzyme – it is estimated that only less than half of the arginine delivered to the body gets into the systemic circulation, and the remaining part is degraded. Here is the succor – citrulline, which can be easily converted into arginine, Studies show that arginine level is more effectively increased by supplementation with citrulline compared to supplementation with arginine itself (!). Simultaneous administration of both amino acids brings even better results.