L-Tyrosine

Last Updated: July 11, 2023

L-Tyrosine is an amino acid that is used as a precursor for the synthesis of the catecholamines dopamine (DA) and norepinephrine (NE). DA and NE are depleted under stressful conditions, which can compromise cognitive function. L-Tyrosine supplementation may help alleviate acute stress-induced cognitive decline by restoring catecholamine levels in the brain.

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L-Tyrosine is most often used for

What is L-tyrosine?

L-Tyrosine is an amino acid found in the diet that is metabolized to produce catecholamines such as dopamine (DA) and norepinephrine (NE).[1] L-tyrosine is also used in the production of thyroid hormones.[2] L-Tyrosine is often taken as a supplement to help increase catecholamine levels depleted during stressful or challenging conditions.[1] It is taken as a free-form amino acid supplement, commonly alone or as part of weight loss or preworkout supplements.

What are L-tyrosine’s main benefits?

The main benefits of L-tyrosine are related to its ability to replenish catecholamine levels in the brain, which can become depleted under stressful conditions.[1] Multiple studies have demonstrated that L-tyrosine can help to prevent declined cognitive function under stressful, cognitively demanding conditions.[3] Although it has not been shown to improve memory under resting conditions, L-tyrosine supplementation has been shown to alleviate reduced memory under acutely stressful conditions.[4] Overall L-tyrosine appears to be safe and well-tolerated at moderate doses, with one 2-week human trial using a dose of 2500 mg, provided three times per day for two weeks,[5] and another trial using single doses of up to 150 mg/kg of body weight (around 10,000 mg for a 68 kg/150 lb individual), both with no adverse effects.[6]

What are L-tyrosine’s main drawbacks?

Although L-tyrosine has shown beneficial effects in some studies, it has a mixed track record for efficacy, with some studies failing to observe positive effects on cognition.[7][3] This may be partially explained by the fact that L-tyrosine increases catecholamine synthesis only when catecholamine levels are depleted, limiting efficacy to sufficiently stressful or challenging conditions. Efficacy may also vary in different individuals, as highlighted by one study that found that the effects of L-tyrosine on cognitive function become detrimental with older age.[7] There are also possible contraindications for L-tyrosine supplementation in people with hyperthyroidism or anyone taking L-dopa or monoamine oxidase inhibitors. If this applies to you, consult with your physician before supplementing with L-tyrosine.

How does L-tyrosine work?

L-Tyrosine is used in the body to make the catecholamines dopamine (DA) and norepinephrine (NE), which can become depleted under stressful or cognitively challenging conditions. After supplementation, L-tyrosine levels in the blood peak after one to two hours, and stay elevated for up to eight hours.[8] L-tyrosine then passes through the blood-brain barrier, where it is absorbed by brain cells and converted in a series of enzymatic reactions to DA, which can be converted to NE through the action of another enzyme.[9] The ability of L-tyrosine to enhance catecholamine synthesis only in neurons that are actively firing may explain its ability to reverse the effects of neurotransmitter depletion during stress.[10]

What are other names for L-Tyrosine?
L-Tyrosine should not be confused with:
  • Taurine
Dosage information

Anecdotally, L-Tyrosine tends to be taken in doses of 500–2000 mg approximately 30–60 minutes before any acute stressor (this tends to be exercise)

Studies in humans showing most anti-stress promise for acute supplemental L-Tyrosine use a dosage range of 100–150 mg/kg of bodyweight which can be taken 60 minutes before exercise; this is a dosage range of 9–13.5 g for a 200 lb person and 7–10 g for a 150 lb person.

If using higher doses and finding digestive issues, this may be split into two doses separated by half an hour (30 and 60 minutes prior to acute stress).

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Update History
2023-07-11 16:56:08

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Written By

Bill Willis

Reviewed By

Nick Milazzo

Research Breakdown

🚧 Under Renovation 🚧

The information in this section is slated for renovation — it will soon be transformed into a more usable (and readable!) form in the coming months. As such, the text in this section may be out of date and not up to Examine’s current standards for writing style.

References
  1. ^Young SNL-tyrosine to alleviate the effects of stress?J Psychiatry Neurosci.(2007-May)
  2. ^Rivlin R, Asper SPTyrosine and the thyroid hormones.Am J Med.(1966-Jun)
  3. ^Jongkees BJ, Hommel B, Kühn S, Colzato LSEffect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A reviewJ Psychiatr Res.(2015 Nov)
  4. ^Shurtleff D, Thomas JR, Schrot J, Kowalski K, Harford RTyrosine reverses a cold-induced working memory deficit in humansPharmacol Biochem Behav.(1994 Apr)
  5. ^M J Sole, C R Benedict, M G Myers, F H Leenen, G H AndersonChronic dietary tyrosine supplements do not affect mild essential hypertensionHypertension.(Jul-Aug 1985)
  6. ^Ondine van de Rest, Mirjam Bloemendaal, Rianne de Heus, Esther AartsDose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in AgingNutrients.(2017 Nov 23)
  7. ^Mirjam Bloemendaal, Monja Isabel Froböse, Joost Wegman, Bram Bastiaan Zandbelt, Ondine van de Rest, Roshan Cools, Esther AartsNeuro-Cognitive Effects of Acute Tyrosine Administration on Reactive and Proactive Response Inhibition in Healthy Older AdultseNeuro.(2018 Apr 30)
  8. ^Glaeser BS, Melamed E, Growdon JH, Wurtman RJElevation of plasma tyrosine after a single oral dose of L-tyrosineLife Sci.(1979 Jul 16)
  9. ^S KAUFMAN, S FRIEDMANDOPAMINE-BETA-HYDROXYLASEPharmacol Rev.(1965 Jun)
  10. ^John D Fernstrom, Madelyn H FernstromTyrosine, phenylalanine, and catecholamine synthesis and function in the brainJ Nutr.(2007 Jun)
Examine Database References
  1. Heart Rate - A B Dollins, L P Krock, W F Storm, R J Wurtman, H R LiebermanL-tyrosine ameliorates some effects of lower body negative pressure stressPhysiol Behav.(1995 Feb)
  2. Body Temperature - James A Lang, Alex C Krajek, Kelsey S Schwartz, Joel E RandOral L-Tyrosine Supplementation Improves Core Temperature Maintenance in Older AdultsMed Sci Sports Exerc.(2020 Apr)
  3. Processing Accuracy - Thomas J, Lockwood P, Singh, A, Patricia, DTyrosine Improves Working Memory in a Multitasking EnvironmentPharmacol Biochem.()
  4. Reaction Time - Catherine O'Brien, Caroline Mahoney, William J Tharion, Ingrid V Sils, John W CastellaniDietary tyrosine benefits cognitive and psychomotor performance during body coolingPhysiol Behav.(2007 Feb 28)
  5. Working Memory - Deijen JB, Orlebeke JFEffect of tyrosine on cognitive function and blood pressure under stressBrain Res Bull.(1994)
  6. Working Memory - Ondine van de Rest, Mirjam Bloemendaal, Rianne de Heus, Esther AartsDose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in AgingNutrients.(2017 Nov 23)
  7. Working Memory - Shurtleff D, Thomas JR, Schrot J, Kowalski K, Harford RTyrosine reverses a cold-induced working memory deficit in humansPharmacol Biochem Behav.(1994 Apr)
  8. Working Memory - Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJTyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training courseBrain Res Bull.(1999 Jan 15)
  9. Working Memory - Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DLThe effects of tyrosine on cognitive performance during extended wakefulnessAviat Space Environ Med.(1995 Apr)
  10. Alertness - Nicole A Coull, Samuel L Watkins, Jeffrey W F Aldous, Lee K Warren, Bryna C R Chrismas, Benjamin Dascombe, Alexis R Mauger, Grant Abt, Lee TaylorEffect of tyrosine ingestion on cognitive and physical performance utilising an intermittent soccer performance test (iSPT) in a warm environmentEur J Appl Physiol.(2015 Feb)
  11. Rate of Perceived Exertion - Les Tumilty, Nicholas Gregory, Manfred Beckmann, Rhys ThatcherNo Influence of Low-, Medium-, or High-Dose Tyrosine on Exercise in a Warm EnvironmentMed Sci Sports Exerc.(2020 Jun)
  12. Rate of Perceived Exertion - Les Tumilty, Glen Davison, Manfred Beckmann, Rhys ThatcherFailure of oral tyrosine supplementation to improve exercise performance in the heatMed Sci Sports Exerc.(2014 Jul)
  13. Rate of Perceived Exertion - Les Tumilty, Glen Davison, Manfred Beckmann, Rhys ThatcherOral tyrosine supplementation improves exercise capacity in the heatEur J Appl Physiol.(2011 Dec)
  14. Dopamine - D D Rasmussen, B Ishizuka, M E Quigley, S S YenEffects of tyrosine and tryptophan ingestion on plasma catecholamine and 3,4-dihydroxyphenylacetic acid concentrationsJ Clin Endocrinol Metab.(1983 Oct)
  15. Dopamine - Li J, Zie FEffects of tyrosine supplementation ration on anaerobic sports capacity and plasma catecholamine levels in soccer athletesBiomed Res.()
  16. Renin Activity - C R Benedict, G H Anderson, M J SoleThe influence of oral tyrosine and tryptophan feeding on plasma catecholamines in manAm J Clin Nutr.(1983 Sep)
  17. Heart Rate - James A Lang, Kevin A SmallerOral l-tyrosine supplementation augments the vasoconstriction response to whole-body cooling in older adultsExp Physiol.(2017 Jul 1)
  18. Heart Rate - Troy D Chinevere, Robert D Sawyer, Andrew R Creer, Robert K Conlee, Allen C ParcellEffects of L-tyrosine and carbohydrate ingestion on endurance exercise performanceJ Appl Physiol (1985).(2002 Nov)
  19. Blood glucose - Erin E Sutton, M Regina Coill, Patricia A DeusterIngestion of tyrosine: effects on endurance, muscle strength, and anaerobic performanceInt J Sport Nutr Exerc Metab.(2005 Apr)
  20. Working Memory - Banderet LE, Lieberman HRTreatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humansBrain Res Bull.(1989 Apr)
  21. Fatigue Symptoms - Harris R Lieberman, Lauren A Thompson, Christina M Caruso, Philip J Niro, Caroline R Mahoney, James P McClung, Gregory R CaronThe catecholamine neurotransmitter precursor tyrosine increases anger during exposure to severe psychological stressPsychopharmacology (Berl).(2015 Mar)
  22. Heart Rate - Joanne DiFrancisco-Donoghue, Ely Rabin, Eric M Lamberg, William G WernerEffects of Tyrosine on Parkinson's Disease: A Randomized, Double-Blind, Placebo-Controlled TrialMov Disord Clin Pract.(2014 Oct 23)
  23. Schizophrenia symptoms - Deutsch SI, Rosse RB, Schwartz BL, Banay-Schwartz M, McCarthy MF, Johri SKL-tyrosine pharmacotherapy of schizophrenia: preliminary dataClin Neuropharmacol.(1994 Feb)
  24. Impulse Control - Lorenza S Colzato, Bryant J Jongkees, Roberta Sellaro, Wery P M van den Wildenberg, Bernhard HommelEating to stop: tyrosine supplementation enhances inhibitory control but not response executionNeuropsychologia.(2014 Sep)
  25. Narcolepsy Symptoms - R D Elwes, H Crewes, L P Chesterman, B Summers, P Jenner, C D Binnie, J D ParkesTreatment of narcolepsy with L-tyrosine: double-blind placebo-controlled trialLancet.(1989 Nov 4)
  26. Heart Rate - M J Sole, C R Benedict, M G Myers, F H Leenen, G H AndersonChronic dietary tyrosine supplements do not affect mild essential hypertensionHypertension.(Jul-Aug 1985)
  27. Depression Symptoms - A J Gelenberg, J D Wojcik, W E Falk, R J Baldessarini, S H Zeisel, D Schoenfeld, G S MokTyrosine for depression: a double-blind trialJ Affect Disord.(1990 Jun)