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L-tyrosine is a non-essential amino acid that can be made from L-phenylalanine in the body.
As well as being incorporated into body proteins, L-tyrosine is the raw material from which a group of neurotransmitters (brain chemicals) called catecholamines are formed.
One of the catecholamines formed from L-tyrosine is adrenalin. Adrenalin, together with other neurotransmitters, helps to focus the mind and improve concentration during Stress (1).
L-tyrosine is also the precursor for thyroid hormone and the Skin pigment melanin (2).
L-tyrosine taken as a supplement has produced excellent results in some types of Depression - specifically tired, apathetic depression as opposed to high Anxiety states. Put simply, L-tyrosine helps replace excitatory neurotransmitters depleted by stress (1,3,4).
Similarly, L-tyrosine supplements are to be recommended in cases of low motivation or poor concentration (1).
Up to 6g/day of L-tyrosine appears to be perfectly safe in human adults, but no more than 2000mg daily is usually necessary for good effect.
L-tyrosine should be avoided by those with high blood pressure or melanoma
MAO inhibitor anti-depressant drugs: It should also not be taken by those on MAO inhibitor anti-depressant drugs.
L-tyrosine should additionally not be taken by pregnant women or schizophrenics.
1. "The Healing Nutrients Within", E R Braverman & C C Pfeiffer, Keats, 1987.