Tyrosine is also used to produce one of the major hormones, thyroxin which plays an important role in controlling metabolic rate, skin health, mental health, and growth rate. Tyrosine is specifically used to treat depression because it is a precursor for those neurotransmitters that are responsible for transmitting nerve impulses and essential for preventing depression. It has been tested on humans for increasing their endurance to anxiety and stress under fatigue. It was proven in research studies that tyrosine supplementation results in increased performance over a control group. Tyrosine was also used with the amino acid tryptophan for treatment of cocaine abuse.
Tyrosine is a mild antioxidant, reacting with free radicals that can cause damage to cells.
It is also known that tyrosine promotes sexual drive. It may also be used as a mild appetite suppressant. Summary L-tyrosine may be effective in treating Parkinson's disease with more favorable clinical results and fewer side effects. Dietary precursors, especially in purified form have been proven to promote the level of precursors in the brain. When taken orally or parenterally, they induce an increase of transmitter formation, further influencing a variety of brain functions.