A studies of tyrosine have shown it to be useful during conditions of Stress, cold, Fatigue and Sleep deprivation, with reductions in stress hormone levels, reductions in stress and improvements in cognitive and physical performance. However, because tyrosine hydroxylase is the rate-limiting enzyme, effects are do not seem to have any major significance on Mood, or cognitive and physical performance during a normal routine.
The daily recommended dose daily dosage is about 100mg for an adult, which amounts to about 6.8 grams (an equivalent to 1–3 capsules of pure tyrosine). It is not recommended to exceed 12000 mg (12g) per day, as excessive doses may decrease the absorption of other Amino Acids.
There are three known parts of tyrosine. In addition to L-tyrosine, there are two additional variations, which include meta-tyrosine and ortho-tyrosine (these both occur in nature). These tyrosine variations are rare and arise through non-enzymatic free-radical hydroxylation of phenylalanine under conditions of oxidative stress.
Please note: L-Tyrosine should not be used with MAO inhibitors (a type of anti-depressant medicine).