Arginine and citrulline are two amino acids that are integral to protein metabolism and utilization, as well as to the maintenance of muscle tissue.* Both are key intermediates in the urea cycle, where they participate in the detoxification of ammonia via the production of urea.* In addition, any arginine not converted to urea enters general circulation where it is distributed to various tissues and metabolized for other uses such as protein synthesis.* Natural color variation may occur in this product.