Nutircost's L-Tyrosine is a pure form of L-Tyrosine. L-Tyrosine is a non-essential amino acid that plays an important role in the production of neurotransmitters dopamine and norepinephrine. These feed directly into the brain which scientists have determined may have a positive effect on cognitive abilities. Tyrosine may also have an effect on the level of mental cognition that a person can reach. In addition, because L-Tyrosine is necessary for the synthesis of thyroid hormone and epinephrine (adrenaline), L-Tyrosine supports healthy glandular function, reduced physical fatigue, and stress response.