Like many other B-complex vitamins, riboflavin must be converted into its active form to be lized by your cells, hence the importance of riboflavin 5'-phosphate supplements. In the human body, this process takes place in the cellular mitochondria when dietary riboflavin is converted by the enzyme riboflavin kinase into riboflavin 5'-phosphate (R5P), which is the principal form of riboflavin found in cells and tissues. Swanson Ultra R-5-p lets your body sidestep this process by delivering the vitamin directly in its active form so it's ready to perform its vital functions in cellular energy metabolism.