L-Tyrosine is also known by the chemical name of 4-hydroxyphenylalanine. It is one of the 22 amino acids that are used by the cells of the human body to synthesize proteins. The word “Tyrosine” comes from the Greek and means cheese. It was first discovered from casein, a cheese protein, in 1846. Tyrosine is found in a number of high protein food sources. This includes chicken, turkey, fish, peanuts, avocados, milk, cheese, yogurt, bananas, and soy products. L-tyrosine is used to produce noradrenaline and dopamine, which in helps improve mood, energy, focus, and stress.