L-tyrosine is an amino acid that can be converted in the brain and in the adrenal glands to dopamine, norepinephrine, and epinephrine (adrenaline) hormones that are depleted by stress, overwork and certain drugs. By replenishing norepinephrine in the brain, mental energy levels may be improved. The conversion step from L-tyrosine to norepinephrine may be enhanced cofactor vitamins B6 and C are consumed with L-tyrosine.
L-tyrosine also acts as a precursor to thyroid hormones, enkephalins and melanin.
Cells in the adrenal medulla synthesize and secrete norepinephrine and epinephrine. Since both norepinephrine and epinephrine can cause smooth muscle (arterial) contraction, care with blood pressure should be taken when supplementing with L-tyrosine.