L-Tyrosine

Tyrosine is not considered an essential amino acid. Tyrosine is a precursor to thyroid, adrenocortical hormones and to dopamine. Some of the symptoms of its deficiency include low body temperature, low blood-pressure, and restless legs. Tyrosine derives from phenylalanine.

Therapeutically, tyrosine has been employed to enhance its derivatives (dopa, dopamine, norepinephrine, and epinephrine) as well as to alter brain activity. Brain tyrosine levels are raised by ingestion of pure tyrosine, with a high carbohydrate meal to lower levels of competing amino acids. A high protein meal will increase blood and brain tyrosine to a degree but not enough to effect neurotransmitter synthesis significantly.

Tyrosine is reported to help some people with Parkinson disease and to aid in relieving depression. Tyrosine has been found to be most effective when there exists a deficiency state. There is evidence that small doses of Tyrosine are more effective in increasing brain levels of neurotransmitters, than large dosages. Although blood and brain levels of tyrosine will increase with large doses, there appears to be an inhibition of the enzyme tyrosine hydroxylase which converts tyrosine to neurotransmitters when large amounts of tyrosine are present.

Tyrosine is not compatible with the intake of MAO drugs (monoaminoxidases).