Solgar DLPA (DL-Phenylalanine) is a mixture of both the D and L forms of the amino acid phenylalanine.  DLPA may have the unique ability to block the enzyme enkephalinase in the central nervous system, thereby sparing feel good hormones such as endorphins and enkephalins. The Solgar DLPA formulation provides Free Form DLPA to promote optimal absorption and assimilation.