Size:120 Count (Pack of 1) 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. Brand Story ----------- By NOW Foods