DL-PhenylalanineThis form of the essential amino acid Phenylalanine is made of equal parts D (synthetic) and L (natural). DLPA activates endorphins which are hormones that trigger and intensify the body's own natural painkilling ability. DLPA can inhibit enzymes that breakdown these endorphins and allow them to do their job by restoring them to normal levels. People with chronic pain typically have lower levels of endorphin activity in their blood and spine fluid.