L-Tyrosine

Summary (The Good, The Bad, and all other Essential Benefits/Effects/Facts Information)

L-tyrosine is a naturally occurring amino acid that is the precursor to the neurotransmitter known as 'adrenaline' (also known as epinephrine). Supplementation with L-tyrosine is able to increase levels of adrenaline in the body and exert the benefits typically associated with adrenaline.

Do Not Confuse With

Taurine

Is a Form of

• Fat-Burner

Does Not Go Well With

• Branched Chain Amino Acids

How to Take (recommended dosage, active amounts, other details)

Typically doses of L-Tyrosine are 500mg-2g, taken acutely before exercise or tests of cognitive performance.

Things to Note

L-tyrosine is stimulatory.

Caution Notice (just some FYI - if needed)

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Detailed Summary

1. Adrenaline and L-tyrosine
2. L-tyrosine Supplementation and Sports
3. L-tyrosine and Neurological disorders
4. L-tyrosine and Phenylketonuria

Edit1. Adrenaline and L-tyrosine

The catecholamine metabolic pathway in vivo starts with the amino acid L-phenylalanine, which gets converted into L-tyrosine by the enzyme phenylalanine hydroxylase. L-tyrosine then gets converted into the compound L-DOPA via tyrosine hydroxylase. L-DOPA is then decarboxylated via aromatic L-amino acid decarboxylase into Dopamine, which later turns into noradrenaline via oxidation from the enzyme dopamine-beta-hydroxylase and then finally converted to adrenaline via Phenylethanolamine-N-methyl-transferase. The last three compounds (Dopamine, NA, Adrenaline) are collectively referred to as 'Catecholamines'; the rate limiting step in this formula is the enzyme tyrosine hydroxylase.^[1]

So basically; Phenylalanine -> Tyrosine -> L-DOPA -> Dopamine -> Adrenaline.

Supplementing with any of the prior substrates has the ability to increase adrenaline levels, given that the enzyme between said substrate and adrenalines are not maxed out.

Edit2. L-tyrosine Supplementation and Sports

L-tyrosine is typically supplemented with to alleviate the decline in neurological performance associated with moderate to long term mental exertion (which can be through study or exercise).

It is suspected in increasing performance from neurally intensive activites, as it does not appear to enhance performance systemically.^[2]

Edit3. L-tyrosine and Neurological disorders

Increasing levels of L-tyrosine in the brain is being looked at as a pharmaceutical method of alleviating neurological decline as catecholamines are typically decreased in states of dementia.

Surprisingly, catecholamines may act as anti-oxidants in the brain and be neuroprotective.^[3]|published=2010|authors=Jodko K, Litwinienko G|journal=Postepy Biochem]

Edit4. L-tyrosine and Phenylketonuria

Phenylketonuria (PKA) is a genetic disease in which the body fails to properly metabolize the amino acid 'phenylalanine', and said amino acid can build up to toxic levels.

Tyrosine has been looked at for possibly alleviating symptoms of PKA, as it was theorized that PKA might also be resultant from a deficiency in tyrosine rather than elevated phenylalanine. Results, however, are preliminary.^[4][5]

Scientific Support & Reference Citations

Nutrition, brain function and cognitive performance

References

1. Nakashima A, et al. Role of N-terminus of tyrosine hydroxylase in the biosynthesis of catecholamines. J Neural Transm. (2009)
2. Meeusen R, Watson P, Dvorak J. The brain and fatigue: new opportunities for nutritional interventions. J Sports Sci. (2006)
3. [Oxidative stress in the neurodegenerative diseases--potential antioxidant activity of catecholamines
4. Webster D, Wildgoose J. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. (2010)
5. Poustie VJ, Rutherford P. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. (2000)

Last Updated: Oct 29, 2011 21:30:09