L-tyrosine (tyrosine) is a non-essential amino acid (one that can be produced by the body) which is a precursor for the neurotransmitters dopamine, norepinephrine, and epinephrine, each of which have important effects on mood, sleep, energy etc.. In the diet, Tyrosine is found in almonds, avocados, bananas, beef, dairy, eggs, fish, lima beans, pumpkin seeds, sesame seeds and soy.
As a supplement Tyrosine has been found to improve cognitive performance and reduce blood pressure in subjects who have been exposed to stressful environments. (NOTE: N-Acetyl L-Tyrosine is a more rapidly absorbed and bioavailable form of the amino acid L-tyrosine, and is less prone to urinary excretion.)
L-tyrosine supplements are available as capsules and in bulk powder.