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
- 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).
Frequently asked questions
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.
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]
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.
There is a low potential for adverse interactions, and no research has been published documenting adverse interactions. However, it’s important to check with your physician or a pharmacist before using L-tyrosine supplements while taking NDRIs.
Norepinephrine and dopamine reuptake inhibitors (NDRIs) are a class of pharmaceuticals used to treat depression, which work by suppressing the absorption of the catecholamines dopamine and norepinephrine within neurons. Their mechanism of action involves blocking a negative feedback mechanism by suppressing a specialized group of receptors responsible for the reuptake of catecholamines within the synapses of neurons. By suppressing norepinephrine/dopamine reuptake, NDRIs prolong the ability of these neurotransmitters to propagate signals in the CNS. L-tyrosine can be converted to catecholamines such as dopamine and norepinephrine by the enzyme tyrosine hydroxylase, but this enzyme is feedback inhibited when catecholamine levels are elevated.[11] In other words, increased catecholamine levels from concurrent NDRI use would likely suppress the enzyme tyrosine hydroxylase, reducing the potential of adverse interactions while taking L-tyrosine supplements.
Although this feedback-inhibition loop limits the potential of adverse reactions on paper, it is unclear whether there are any variations within individuals that increase the risk of adverse reactions. It’s also important to keep in mind that if you’re taking NDRIs, L-tyrosine supplements may have little effect on dopamine or norepinephrine levels — the primary reason for taking tyrosine supplements in the first place.
There are no known drug interactions between selective serotonin reuptake inhibitor (SSRI) medications and L-tyrosine supplements. However, because L-tyrosine supplements may have an effect on neurotransmitter levels,[12] it’s important to check with your physician before starting supplementation.
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]
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References
- ^Young SNL-tyrosine to alleviate the effects of stress?J Psychiatry Neurosci.(2007-May)
- ^Rivlin R, Asper SPTyrosine and the thyroid hormones.Am J Med.(1966-Jun)
- ^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)
- ^Shurtleff D, Thomas JR, Schrot J, Kowalski K, Harford RTyrosine reverses a cold-induced working memory deficit in humansPharmacol Biochem Behav.(1994 Apr)
- ^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)
- ^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)
- ^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)
- ^Glaeser BS, Melamed E, Growdon JH, Wurtman RJElevation of plasma tyrosine after a single oral dose of L-tyrosineLife Sci.(1979 Jul 16)
- ^S KAUFMAN, S FRIEDMANDOPAMINE-BETA-HYDROXYLASEPharmacol Rev.(1965 Jun)
- ^John D Fernstrom, Madelyn H FernstromTyrosine, phenylalanine, and catecholamine synthesis and function in the brainJ Nutr.(2007 Jun)
- ^Daubner SC, Le T, Wang STyrosine hydroxylase and regulation of dopamine synthesisArch Biochem Biophys.(2011 Apr 1)
- ^Hase A, Jung SE, aan het Rot MBehavioral and cognitive effects of tyrosine intake in healthy human adults.Pharmacol Biochem Behav.(2015-Jun)
