The amino acid tyrosine is best-known for its role in the production of thyroid hormones, which are made purely from tyrosine and the mineral iodine. The thyroid governs our metabolism, including the production of energy from the food that we eat; and it has an important role in growth too. Tyrosine is also needed for our body to make dopamine – a neurotransmitter and hormone whose roles include a feeling of reward or pleasure that motivates us to continue an activity or behaviour – for example when you’ve had a good session at the gym! And from dopamine, the body makes noradrenaline and adrenaline, hormones that give us ‘get up and go’ and get us ready for action.

As dopamine and noradrenaline/adrenaline also play a role in mood (together with serotonin), tyrosine has been studied for its potential to relieve depression. A clinical trial from 2004 found that volunteers who took an amino acid mixture that did not contain tyrosine and phenylalanine (the amino acid precursor to tyrosine) showed more behaviours consistent with low mood and depression compared to those taking a balanced amino acid mixture.[23]. A similar effect was observed in a clinical trial from 2000 on 41 healthy women, finding vulnerability to lowered mood in the group taking a formula deficient in tyrosine and phenylalanine.[24]




23. McLean A et al. The effects of tyrosine depletion in normal healthy volunteers: implications for unipolar depression. Psychopharmacology (Berl). 2004 Jan;171(3):286-97.
24. Leyton M et al. Effects on mood of acute phenylalanine/tyrosine depletion in healthy women. Neuropsychopharmacology. 2000 Jan;22(1):52-63.




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