L-Theanine Summary:

L-Theanine is an amino acid analogue found commonly in the plant that gives us green, black and oolong tea (Camellia sinensis).

In recent years it has shown an abundance of beneficial actions on the brain and vascular systems. It works through several pathways including the dopaminergic pathway, vasodilation including the cerebral arteries, and through a possible mimicing action of glutamic acid.

L-Theanine is easily obtained in pure form online, or through high quality shade grown green tea such as matcha or gyokuro. It combines very well with caffeine, and has been shown to ammeliorate many of the negative side effects of this common stimulant.

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Where Does It Come From?

L-theanine is an amino acid isomer found naturally in plants of the Theaceae family. camellia sinensis primarily. In this species, the L-Theanine content is especially high in shade grown crops like Gyokuro or high quality sencha.

Theaceae Family

Camellia sinensis

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Found in some fungal species

 High-quality Matcha is a great source of L-theanine

High-quality Matcha is a great source of L-theanine


+ Indications

  • Depression
  • In combination with caffeine
  • Anxiety
  • To improve memory
  • To improve concentration

+ Contraindications

None noted.

+ Mechanisms

  • Dopaminergic
  • Cerebrovasodilator

General Actions:

  • Relaxant
  • Sedative (Mild)
  • Euphoric
  • Reduces stress
  • Vasodilator
  • Neuroprotective
  • Anxiolytic
  • Antidepressant (Mild)


500 - 750 mg/day

Split up into 2-3 doses per day.

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Chemical Description:

L-Theanine is an amino acid analogue of the proteogenic amino acids L-glutamate and L-glutamine [1]. 



Still compiling research...


Pharmacology and Medical Research:

+ Dopaminergic

Still Compiling research.

+ Neuroprotective

Still compiling research.



No negative side effects were noted in the dosage range of 200-400 mg/day.



Synergistic with caffeine. Works to reduce the side effects of the caffeine, and improve the cognitive enhancing ability. L-theanine is calming and imporves concentration, caffeine stimulates the mind and reduces fatigue and sleepiness. 

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Justin Cooke

The Sunlight Experiment

Updated: March 2017

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  1. Nathan PJ, Lu K, Gray M, Oliver C (2006) The neuropharmacology of L- theanine(N-ethyl-L-glutamine): A possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother 6:21–30