ALA: 1. Alpha-linolenic acid 2.Aminolevulinic acid, a naturally occurring chemical in the body that is converted to protoporphyrin IX, a light-sensitive compound. Aminolevulinic acid has been used in the photodynamic therapy of skin precancer and cancer. In this therapy topical treatment with forms of ALA sensitizes the tissues to light. Then a special blue or red light depending upon the form of ALA used is then shone on the tissue to be treated. The reaction of the ALA treated tissues to the light source can kill cells.