L-theanine is an amino acid (a building block for proteins) found in green tea. This natural nootropic was first isolated from Green Tea in 1949.[1] Since then, it has been researched for its ability to support brain health and enhance focus. People use L-theanine for reducing anxiety and high blood pressure, for relieving of Alzheimer’s disease, and for making cancer drugs more effectively.[2]


L-theanine has a lot of different benefits for mood, cognitive function and general health. L-theanine enhances the production of GABA, an amino acid and neurotransmitter, which works to calm the mind and relax the body by hindering over-excited stress signals in the brain.
There have been a number of studies which prove the benefits of Theanine. The first was from a paper published in 1999 by Food Science and Technology where researchers observed Theanine’s production of alpha brain waves allowed them to be more relaxed and yet alert enough to perform complex tasks. It also may help reduce the side effects of chemo treatment due to the calming and relaxing effects.
The common health benefits of L-Theanine include:

  • Reduces anxiety and stress [5]
  • Improves cognitive function [6]
  • Protects heart and blood vessels [7]
  • Acts as an antioxidant [8]
  • Increases sleep quality [9]
  • Reduces symptoms of schizophrenia [10]
  • Enhances immune function [11]
  • Helps people who are fighting cancer [12]
  • Reduces symptoms of depression [13]
  • Promotes weight loss [14]
  • May heal stomach ulcers [15]
  • Boosts important brain chemicals [16]
  • Helps people who have Alzheimer’s disease [17]

Because of its reducing anxiety and having calming effects on the nerves, L-Theanine is called a neuro-vitamin.
L-Theanine lowers the heart rate, and reduces blood pressure overall that is enhanced circulation throughout the body, which can have a tremendous positive impact on everything from lung capacity to arthritis pain.

How it works

L-Theanine (gamma-glutamylethylamide) is an analog of glutamate and glutamine that is capable of crossing the blood-brain barrier.
It begins by targeting a number of different neurotransmitters which include Serotonin, Dopamine, GABA, and Norepinephrine. These are all powerful brain chemicals which have a number of effects upon cognitive processes, sleep and relaxation cycles, and even pleasure and the brain’s reward system.
Whereas its deeper mechanisms are still under investigation, there is enticing proof that L-theanine influences expression of genes in brain areas responsible for fear and aggression (amygdala) and memory (hippocampus), helping to balance the behavioral responses to stress, and potentially improve conditions such as mood disorders, post-traumatic stress disorder (PTSD), and substance dependence.[3] 
Latest studies show that L-theanine is capable of hindering both the biochemical and structural damage to brain cells induced by aluminum, offering yet another means by which this nutrient can hinder or slow cognitive decline.[4]
The newest studies show that L-theanine has properties that may both help to obstruct strokes and to mitigate the damage caused when they do occur.
This supplement might even defend the brain and support better maintenance of brain cells and it inhibits neurons from damage by blocking over-stimulation of the cells and protects them from low levels of oxygen.


Serious L-theanine side effects are practically non-existent, though there are occasional minor ones. The only common side effects are dizziness, nausea, and headaches evident in clinical studies of L-theanine. Taking theanine along with stimulant drugs might decrease the effectiveness of stimulant drugs.


To achieve L-Theanine’s cognitive lift, sharpening of focus and energy, and relaxing anti-anxiety power, simply fine tune the amount to your body’s particular requirements. The recommended dosage of L-Theanine is 200 to 400 mg once or twice daily (1200 maximum a day). It is advised not to take L-theanine with cholesterol lowering medications.