Tyrosine is a non-essential amino acid synthesized in the body from the essential amino acid phenylalanine. The typical dietary amount provided by a 3 oz portion of animal protein is 0.3-1 g of tyrosine. Tyrosine is the precursor amino acid from which the body makes Dopamine (with vitamin B6 as cofactor), which is then converted to Nor-epinephrine (with vitamin C as cofactor ) and then to Epinephrine (with SAMe as cofactor).

Tyrosine competes for uptake with other large neutral amino acids, so in order to maximize absorption from the supplemented Tyrosine into various tissues (such as brain, adrenals, nerves), it should be taken on an empty stomach, or two hours away from a protein containing meal.