L-Arginine is necessary for the execution of many physiological processes. These physiological processes include hormone secretion, an increase in growth hormone output, the removal of toxic waste products from the body, and immune system defences. Because Arginine is a precursor of nitric oxide [which is responsible for vasodiolation 3] it is often used for supporting healthy sexual function. Recently, dietary supplements containing Arginine have become popular due to Arginine's nitric oxide producing ability, its ability to scavenge free radicals, as well as its ability to signal muscle cells, release growth hormone, support healthy cholesterol, and enhance fat metabolism. Arginine helps regulate salt levels in the body. For this reason, it should be of interest to competing bodybuilders, as retaining water under the skin can make one looks smooth, bloated and washed out. The nitrogen retaining abilities of Arginine are well-known within the bodybuilding and scientific communities. Arginine is also believed to be crucial for muscle growth due to its vasodilating abilities, as well as its ability to participate in protein synthesis.