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.
Where is it found?
Dairy products, meats, fish, wheat, oats, and most other protein-containing foods contain tyrosine.
L-tyrosine has been used in connection with the following conditions (refer to the individual health concern for complete information):
| Science Ratings | Health Concerns |
|---|---|
 |
|
 |
Phenylketonuria (for deficiency) |
 |
|
| Reliable
and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies
suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal
or no scientific evidence. For a supplement, little scientific support and/or minimal health
benefit. |
|
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.
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.
