What Is It?
Tyrosine is one of the non-essential amino acids (can be manufactured by the body) and has powerful physiological effects when both administered alone and provided in high concentrations.
What Does It Do?
Tyrosine is an amino acid and nutrient precursor for approximately 90% of the brain's 3 stimulatory catecholamines (dopamine, norepinephrine, and epinephrine).
For a dietary neurotransmitter precursor to be important:
- Blood concentrations must vary with dietary intake.
- It must cross the blood brain barrier.
- Its transport systems must be able to accommodate more precursor than what is regularly available.
- The levels of the precursor are what limit neurotransmitter formation.
Since tyrosine meets these qualifications, it's evident that a large increase in dietary tyrosine will lead to increases in both brain and peripheral catecholamine concentrations. Human studies confirm that large doses of tyrosine (33mg/kg, 3x per day) can increase blood and urinary catecholamines by up to 25%.
By increasing brain neurotransmitter concentrations, tyrosine can help increase attention and combat performance decrements during sustained efforts, especially when sleep deprived. In addition to this mild stimulant effect, tyrosine may act as an "anti-stress supplement", suppressing rises in cortisol and the norepinephrine depletion associated with the stress response. Finally, tyrosine supplementation may reduce reaction time.
Where Does It Come From?
Tyrosine is a basic dietary component and is present in protein-containing foods. However, the provision of this amino acid individually can lead to more rapid digestion and absorption as well as increased blood concentrations.
How Do I Use It?
For strength athletes, 3g of tyrosine taken both before and after exercise can improve both workout intensity and recovery of the CNS. Since tyrosine can increase catecholamine synthesis and caffeine and green tea can increase catecholamine release, these compounds should act synergistically to increase arousal and performance.
N-acetyl-L-tyrosine acts similarly to tyrosine. The main difference is that acetylation (adding an acetyl group) of the nitrogen terminus (end) of the amino acid makes it more soluble in water. Increased solubility means better dissolution in water and potentially increased digestion and absorption of the amino acid. Most people report the similar effects to tyrosine at ½ the dose. Therefore 1.5g of N-acetyl-L-tyrosine should do the trick.
| Credibility Rating: |   |
Rating Scale:4/4 - This supplement/regimen has significant scientific backing and can produce significant benefits in most individuals.
3/4 - There exists a sound theoretical basis for its ergogenic effects; may work in certain individuals; further research is needed to elucidate their respective effects. 2/4 - Science is equivocal, animal data and human data may be conflicting; or mechanism of action may be unclear.
1/4 - Little or no science as well as poor theoretical foundation.
Scientific References:
- Agharanya J, et al. Am J Clin Nutr. Jan;34(1):82-7, 1981.
- Melamed E. J Neural Transm. 47(4): 299-306, 1980
- Neri D, et al. Aviat Space Environ Med 66(4): 313-9, 1995.
- Reinstein D et al. Life Sci. 37(23): 2157-63, 1985.
- Lieberman H, et al. Am J Clin Nutr. 42(2): 366-70, 1985.
About The Author
John M. Berardi is one of the world's foremost experts in the field of human performance and nutrition. His company, Science Link, provides unique and highly effective training, nutrition, and supplementation programs for high level athletes as well as recreational exercisers. John is a prolific author and a sought after speaker and consultant. Visit www.johnberardi.com for more information about John and his team. Also, check out his new DVD entitled "No Nonsense Nutrition".
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