Nutritional Supplement

L-Tyrosine

Also indexed as: Tyrosine

Possible Deficiencies

Some people affected by PKU are deficient in tyrosine. Tyrosine levels are occasionally low in depressed people.12 Any person losing large amounts of protein, such as those with some kidney diseases, may be deficient in several amino acids, including tyrosine.13

Side Effects

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.

References

1. Owasoyo JO, Neri DF, Lamberth JG. Tyrosine and its potential use as a countermeasure to performance decrement in military sustained operations. Aviat Space Environ Med 1992;63:364-9 [review].

2. Deijen JB, Wientjes CJ, Vullinghs HF, et al. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull1999;48:203-9.

3. Neri DF, Wiegmann D, Stanny RR, et al. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med 1995;66:313-9.

4. Banderet LE, Lieberman HR. Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain Res Bull 1989;22:759-62.

5. Shurtleff D, Thomas JR, Schrot J, et al. Tyrosine reverses a cold-induced working memory deficit in humans. Pharmacol Biochem Behav 1994;47:935-41.

6. Deijen JB, Orlebeke JF. Effect of tyrosine on cognitive function and blood pressure under stress. Brain Res Bull 1994;33:319-23.

7. Dollins AB, Krock LP, Storm WF, et al. L-tyrosine ameliorates some effects of lower body negative pressure stress. Physiol Behav 1995;57:223-30.

8. Rose DP, Cramp DG. Reduction of plasma tyrosine by oral contraceptives and oestrogens: a possible consequence of tyrosine aminotransferase induction. Clin Chim Acta 1970;29:49-53.

9. Moller SE. Tryptophan and tyrosine availability and oral contraceptives. Lancet 1979;2:472 [letter].

10. Kishimoto H, Hama Y. The level and diurnal rhythm of plasma tryptophan and tyrosine in manic-depressive patients. Yokohama Med Bull 1976;27:89-97.

11. Gelenberg AJ, Wojcik JD, Growdon JH, et al. Tyrosine for the treatment of depression. Am J Psychiatry 1980;137:622-3.

12. 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.

13. 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.

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.