DL-Phenylalanine. Free Form. Gluten Wheat & Dairy Free. Suitable for Vegetarians. 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. This formulation provides Free Form DLPA to promote optimal absorption and assimilation.