L-Tyrosine has been shown to assist in the production of melanin, the pigment found in hair and skin. Tyrosine is also used by the thyroid and adrenal glands to manufacture natural hormones, which regulate the body's ability to produce energy. Tyrosine is a precursor to dopamine, and therefore, plays a role in neurotranmission signaling and the regulation of depression. It also serves to release the appetite suppressing hormone, CCK, and assists in combatting allergic reactions.