WHAT IS DL PHENYLALANINE? DL Phenylalanine (DLPA) is a form of the essential amino acid Phenylalanine. It is made up of a combination of D-Phenylalanine, which is produced synthetically, & L-Phenylalanine, which is naturally occurring. DL Phenylalanine is not naturally occurring due to it needing to be synthesised through the combination of D-Phenylalanine & L-Phenylalanine. Phenylalanine itself is however a naturally occurring substance & is found in various high protein foods such