L-Theanine and the Brain

L-theanine (N-ethyl-L-glutamine) is a non-proteinaceous amino acid that is found in high amounts almost exclusively in tea (Camellia sinensis). In fact, L-theanine accounts for around 50 % of the amino acids in tea leaves. L-theanine is structurally similar to glutamic acid. L-theanine is of interest nutritionally because it appears to have an ability to increase calmness and focus in humans and this relates to the way it interacts with the brain. L-theanine is able to cross the blood brain barrier and here it can interact with neurones such as the N-methyl-D-aspartate (NMDA) receptor to antagonise its activity. This reduces the excitability of the brain and therefore explains the calming effects of the amino acid. L-theanine also appears to be able to increase synthesis of a number of neurotransmitters including GABA, serotonin and dopamine, and this may have particular mood-elevating effects. Drinking tea has been shown to have these effects, but L-theamine can also be taken as a supplement in powder form.  

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Nathan, P.J., Lu, K., Gray, M. and Oliver, C. 2006. The neuropharmacology of L-theanine (N-ethyl-L-glutamine) a possible neuroprotective and cognitive enhancing agent. Journal of Herbal Pharmacotherapy. 6(2): 21-30

About Robert Barrington

Robert Barrington is a writer, nutritionist, lecturer and philosopher.
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