L-tyrosine is a nonessential amino acid
(protein building block) that the body synthesizes from phenylalanine, another amino acid. Tyrosine is
important to the structure of almost all proteins in the body. It is also the precursor of
several neurotransmitters, including L-dopa, dopamine, norepinephrine, and epinephrine.
L-tyrosine has been used
in connection with the following conditions (refer to the individual
health concern for complete information):
Who is likely to be deficient?
Some people affected by PKU are deficient
in tyrosine. Tyrosine levels are occasionally low in depressed people.1 Any person losing large
amounts of protein, such as those with some kidney diseases, may be deficient in several amino acids, including tyrosine.2
How much is usually taken?
Most people should not supplement with L-tyrosine. Some human research with people
suffering from a variety of conditions used 100 mg per 2.2 pounds of body weight, equivalent
to about 7 grams per day for an average-sized person. The appropriate amount to use in people
with PKU is not known, therefore, the
monitoring of blood levels by a physician is recommended.
Are there any side effects or interactions?
L-tyrosine has not been reported to cause any serious side effects. However, it is not
known whether long-term use of L-tyrosine, particularly in large amounts (such as more than
1,000 mg per day) is safe. For that reason, long-term use of L-tyrosine should be monitored by
a doctor.
Vitamin B6, folic acid, and copper are necessary for conversion of L-tyrosine into
neurotransmitters.
Are there any drug
interactions?
Certain medicines may interact with L-tyrosine. Refer to drug interactions for a list of those medicines.
References:1. Chiaroni P, Azorin JM, Bovier P, et al. A multivariate analysis of red
blood cell membrane transports and plasma levels of L-tyrosine and L-tryptophan in depressed
patients before treatment and after clinical improvement. Neuropsychobiology
1990;23:1–7.
2. Alvestrand A, Ahlberg M, Forst P, Bergstrom J. Clinical results of
long-term treatment with a low protein diet and a new amino acid preparation in patients with
chronic uremia. Clin Nephrol 1983;19:67–73.