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Tyrosine

Scientific Name(s): 4-hydroxyphenylalanine, C9H11NO3
Common Name(s): L-tyrosine, Tyrosine

Medically reviewed by Drugs.com. Last updated on Jan 10, 2018.

Clinical Overview

Use

There is no evidence to support the use of tyrosine in the metabolic genetic disorder phenylketonuria. Some evidence for improved cognitive performance in conditions of stress, including sleep deprivation, exists. Clinical trial data for other conditions is limited and does not support tyrosine supplementation, including for the enhancement of sports performance.

Dosing

Limited clinical studies use 100 to 150 mg/kg per day. Manufacturers commonly recommend 500 to 1,500 mg/day, and dosages of more than 12 g/day are not recommended.

Contraindications

Tyrosine is contraindicated in hyperthyroidism or Graves disease because it may increase levels of thyroid hormone. Coadministration of tyrosine with monoamine oxidase inhibitors (MAOIs) is contraindicated.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

Coadministration of tyrosine and MAOIs is contraindicated. Tyrosine could increase levels of thyroid hormone and levodopa.

Adverse Reactions

Information is limited. Tyrosine supplementation may trigger migraine.

Toxicology

Information is limited.

Source

Tyrosine is made endogenously from phenylalanine and can be found in soy products, milk, cheese, yogurt, chicken, turkey, fish, peanuts, almonds, bananas, lima beans, avocado, pumpkin seeds, and sesame seeds.Zimmermann 2001

History

The name tyrosine is derived from the Greek tyri, meaning "cheese." Tyrosine was first identified in cheese protein casein in 1846 by German chemist Justus von Liebig.

Chemistry

Tyrosine is a nonessential, yet indispensable, amino acid made endogenously and eaten in a usual diet. It is a fundamental building block for proteins, specifically for neurotransmitters. Tyrosine is converted to L-dopa, dopamine, epinephrine, norepinephrine, triiodothyronine (T3), thyroxine (T4), and melanin.

Uses and Pharmacology

Depression

Animal data

Research reveals no recent animal data regarding the use of supplemental tyrosine for use in depression.

Clinical data

Despite a theoretical basis for the use of tyrosine in depression, studies conducted in the 1980s using small sample sizes did not show any benefit.Meyers 2000, Parker 2011 More recent studies focused on serotonin precursors, revealing little evidence of a place in therapy for tyrosine.Meyers 2000, Parker 2011, Fernstrom 2000

Exercise/Performance

Animal data

Research reveals no recent animal data regarding the use of supplemental tyrosine for the use of performance enhancement.

Clinical data

Limited clinical studies provide equivocal data on the effects of supplemental tyrosine in exercise,Chinevere 2002, Tumilty 2011 with older studies conducted in the 1980s reporting more positive findings. Among 8 cyclists exercising in heat, tyrosine 150 mg/kg appeared to improve endurance,Tumilty 2011 while a similar trial also conducted among cyclists resulted in increased plasma tyrosine levels but not improved performance; however, tyrosine may have altered their perception of fatigue.Chinevere 2002

The effect of tyrosine on core cognitive-control performance, as measured by stopping overt responses, was investigated in a small double-blind, randomized, placebo-controlled cross-over study in 22 young healthy female adults. One hour after administration of L-tyrosine 2 g (in 400 mL orange juice), participants were observed to more efficiently inhibit unwanted actions compared to the placebo phase (P<0.05). Response execution was not affected and no significant changes were found in physiological parameters (eg, blood pressure, heart rate) or mood.Colzato 2014

Parkinson disease

Animal data

Limited studies with animal models of Parkinson disease provide little evidence of supplemental tyrosine effect.Fernstrom 2000, Feve 2012

Clinical data

Tyrosine hydroxylase is the rate-limiting step in the production of L-dopa and dopamine, forming the basis for the use of supplemental tyrosine. However, clinical trial data supporting a place in therapy are lacking.Fernstrom 2000, Feve 2012

Phenylketonuria

Tyrosine deficiency is rare, but possible among people with phenylketonuria because of their avoidance of phenylalanine-containing foods such as milk, eggs, and meat. Tyrosinemia is also rare.Glaeser 1979

Animal data

Research reveals no recent animal data regarding the use of supplemental tyrosine in phenylketonuria.

Clinical data

A Cochrane meta-analysis of 6 trials with a total of 56 patients found that increased blood tyrosine levels result from supplementation. However, this does not translate to improvement in any outcome measures, including intelligence, neurophysiological performance, growth, nutritional status, quality of life, or mortality.Posner 2009 A case study suggests a role for tyrosine supplementation in patients with attention deficit hyperactivity disorder symptoms who also have phenylketonuria.Webster 2013

Stress

Animal data

Research reveals no recent animal data regarding the use of supplemental tyrosine for the use of stress prevention. Tyrosine has been shown to impair enzymes of energy metabolism in the cerebral cortex of rats, but the implications of this finding are unclear.de Andrade 2012

Clinical data

Studies evaluating supplemental tyrosine's role in mitigating the effects of stress on cognitive performance and memory deficit have generally found positive, but limited, effects (and lesser than for amphetamine).Deijen 1999, Fernstrom 2000 Among military cadets (N = 21), cognitive performance was supported by tyrosine 10 g/day during physical and psychological training.Deijen 1999 Tyrosine 300 mg/kg in 2 divided doses mitigated the stress-related decrease in cognitive performance induced by cold immersion in another small study.Mahoney 2007 Following sleep deprivation, tyrosine 150 mg/kg improved some aspects of cognitive and motor performance in another small study.Magill 2003 At a dose of 100 mg/kg, L-tyrosine administered 90 minutes prior to heat exposure (45°C x 90 minutes) in 10 healthy young males from the Indian military mitigated the reduction in information processing and cognitive decline seen during the placebo phase of a double-blind, randomized, cross-over study. Tyrosine was also observed to increase plasma norepinephrine levels compared to placebo.Kishore 2013

Dosing

Tyrosine is unable to cross the blood-brain barrier, despite brain tyrosine levels being dependent on plasma concentrations.Glaeser 1979 An alternative form, N-alpha-linolenoyl tyrosine, has been developed to overcome this issue.Yehuda 2002 Coadministration of tyrosine with vitamin B6, folate, and copper could enhance conversion of tyrosine to brain neurotransmitters.

Limited clinical studies use 100 to 150 mg/kg per day. A single dose of 2 g has been used in a cognitive performance trial.Colzato 2014, Kishore 2013, Magill 2003, Mahoney 2007, Tumilty 2011

Manufacturers commonly recommend 500 to 1,500 mg/day, and dosages of more than 12 g/day are not recommended.

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

Case reports are lacking; however, tyrosine is contraindicated in patients taking MAOIs, including isocarboxazid, phenelzine, tranylcypromine, and selegiline. Because tyrosine could increase levels of thyroid hormone and levodopa, caution is warranted.

Adverse Reactions

Case reports are lacking; however, higher plasma tyrosine levels have been noted in cases of chronic migraine.D'Andrea 2013

Toxicology

Symptoms associated with hereditary tyrosinemia, including the development of skin and eye lesions, were apparent at plasma levels 10 times of that found following administration of tyrosine 150 mg/kg in clinical trials.Glaeser 1979 L-tyrosine has been safely used as an adjuvant in vaccine preparation.Baldrick 2002

References

Baldrick P, Richardson D, Wheeler AW. Review of L-tyrosine confirming its safe human use as an adjuvant. J Appl Toxicol. 2002;22(5):333-344.12355563
Chinevere TD, Sawyer RD, Creer AR, Conlee RK, Parcell AC. Effects of L-tyrosine and carbohydrate ingestion on endurance exercise performance. J Appl Physiol (1985). 2002;93(5):1590-1597.12381742
Colzato LS, Jongkees BJ, Sellaro R, van den Wildenberg WP, Hommel B. Eating to stop: tyrosine supplementation enhances inhibitory control but not response execution. Neuropsychologia. 2014;62:398-402.24433977
D'Andrea G, D'Amico D, Bussone G, et al. The role of tyrosine metabolism in the pathogenesis of chronic migraine. Cephalalgia. 2013;33(11):932-937.23493762
de Andrade RB, Gemelli T, Rojas DB, et al. Tyrosine impairs enzymes of energy metabolism in cerebral cortex of rats. Mol Cell Biochem. 2012;364(1-2):253-261.22311600
Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJ. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999;48(2):203-209.10230711
Fernstrom JD. Can nutrient supplements modify brain function? Am J Clin Nutr. 2000;71(suppl 6):1669S-1675S.10837313
Feve AP. Current status of tyrosine hydroxylase in management of Parkinson's disease. CNS Neurol Disord Drug Targets. 2012;11(4):450-455.22583428
Glaeser BS, Melamed E, Growdon JH, Wurtman RJ. Elevation of plasma tyrosine after a single oral dose of L-tyrosine. Life Sci. 1979;25(3):265-271.481129
Kishore K, Ray K, Anand JP, Thakur L, Kumar S, Panjwani U. Tyrosine ameliorates heat induced delay in event related potential P300 and contingent negative variation. Brain Cogn. 2013;83(3):324-329.24141022
Magill RA, Waters WF, Bray GA, et al. Effects of tyrosine, phentermine, caffeine D-amphetamine, and placebo on cognitive and motor performance deficits during sleep deprivation. Nutr Neurosci. 2003;6(4):237-246.12887140
Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav. 2007;92(4):575-582.17585971
Meyers S. Use of neurotransmitter precursors for treatment of depression. Altern Med Rev. 2000;5(1):64-71.10696120
Parker G, Brotchie H. Mood effects of the amino acids tryptophan and tyrosine: 'Food for Thought' III. Acta Psychiatr Scand. 2011;124(6):417-426.21488845
Posner J, Gorman D, Nagel BJ. Tyrosine supplements for ADHD symptoms with comorbid phenylketonuria. J Neuropsychiatry Clin Neurosci. 2009;21(2):228-230.19622700
Tumilty L, Davison G, Beckmann M, Thatcher R. Oral tyrosine supplementation improves exercise capacity in the heat. Eur J Appl Physiol. 2011;111(12):2941-2950.21437603
Webster D, Wildgoose J. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. 2013;6:CD001507.23737086
Yehuda S. Possible anti-Parkinson properties of N-(alpha-linolenoyl) tyrosine: a new molecule. Pharmacol Biochem Behav. 2002;72(1-2):7-11.11900763
Zimmermann M. Burgerstein's Handbook of Nutrition: Micronutrients in the Prevention and Therapy of Disease. Stuttgart; New York: Thieme; 2001.

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This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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