Here’s the scenario; you’re feeling a little sluggish and need a boost. You think about putting away a quick cup of coffee but dread the crash and not to mention the jitters that can come with over-caffeination. 

It’s a common situation millions of us face every day. Creeping up around lunchtime or at some point in our afternoon, we tend to search for something to close out the remainder of the day. 

While there might be a number of hacks or solutions to this problem, it really depends on who you are, what your diet is and how much you sleep. For the majority of us, this can be repaired with our good friend L-theanine.

L-theanine is an amino acid found in green tea. 

Green tea has a long history for its relaxation, and health benefits.  While green tea has skyrocketed in popularity lately, L-theanine is still not common in the diet of most people, despite its prominence in tea leaves (Camellia sinensis).


L-theanine is used for relaxation without the sedative (sleepy) unwanted effects. It can also play a role in improving memory, and attention, especially when combined with a caffeine source (hello, coffee).

To understand why L-theanine is such a great amino acid, we ought to first understand how it works.

L-theanine in the brain

If you are anything like us, you likely love the words Molecular Mechanism when it comes to neuroscience.  

No? Just us?

Either way, here is a rundown on how theanine works in your brain.

L-theanine blood levels peak within 1 hour and can stay elevated up to 5 hours after ingesting it.  Just like Tyrosine, L-theanine can pass through the blood brain barrier (the wall in the brain that says what can go in and out).  

The mechanism of L-theanine is pretty complicated, and still not well understood, however, there is some very cool literature regarding its molecular mechanism.  

Let’s look at the central nervous system as a whole.  There are two main competing neurotransmitters: the inhibitory neurotransmitter, GABA, and the excitatory neurotransmitter, glutamate. The GABA and glutamate pathways are linked to many other neurotransmitters like dopamine, and serotonin. Changes in one of these two neurotransmitters can affect other neurotransmitters.  

Oral ingestion of L-Theanine increases GABA release.  This makes sense, it's promoting inhibition and relaxation, but how?

Many believe it promotes GABA release indirectly by interacting with glutaminergic neurons (neurons that release glutamate). Because L-theanine’s molecular structure is similar to the molecular structure of the amino acid glutamine and glutamate, it can block transporters and receptors important for the release of glutamate.


This means L-theanine is changing the balance of neurotransmitters in the brain, promoting GABA (inhibitory) over glutamate (excitatory), consequently, increasing other neurotransmitters like dopamine and serotonin. 

To put it in simple terms, L-theanine can activate the brain’s calming pathways, as well as influence other neurotransmitters important for mood, motivation, attention, and memory.  

How do we know theanine calms your brain?

It’s all in L-theanine mechanism of action.  Think of a pharmacological drug to promote relaxation, and to reduce anxiety.  A classical one is a class of drugs called benzodiazepines. These drugs not only relax but act as a sedative.  Similar to L-theanine, benzodiazepines increase the effects of GABA in the brain. Contrary to L-theanine, benzodiazepines interact directly with the GABA receptors.  L-theanine on the other hand indirectly increases GABA levels.  The indirect stimulation of the GABA pathway is believed to be the reason why L-theanine supplementation can not only relax but decrease anxiety, without the unwanted sedation side effects.  

What does the brain tell you about L-theanine

Your brain cells work through sets of electrical impulses.  These impulses can be seen using a device called an electroencephalogram (EEG).  Different brain wave patterns can say a lot about a person's state of mind.  Here is a run down of some different wave types and what they mean: 

  • Beta waves are characteristic of being awake and alert
  • Alpha waves are awake and relaxed
  • Theta waves are when you are sleeping 
  • Delta waves are associated with deep sleep.

What does all of this have to do with L-theanine?

Taking L-theanine can promote alpha wave activity, which means you are awake and relaxed.  What’s even more interesting, is that increases in alpha wave patterns are linked to decreases in circulating cortisol levels.  In times of high stress, L-theanine can promote relaxation, while also improving attention, motivation, cognition, and memory.

L-theanine and caffeine

The effects of L-theanine is often in combination with caffeine because of its synergistic effects.  Together, they can increase attention, alertness and accuracy in healthy adults during cognitive testing. When taking a coffee, we are all aware of that brutal caffeine crash or “jitters, L-theanine supplementation cans actually dampens that crash and reduces the "jitters" associated with caffeine intake and actually enhances caffeine's cognitive boosting activities.

L-theanine is one of those nutrients that is a no brainer: it helps relax, reduces anxiety and stay alert. As a bonus, it increases your cognitive benefits when paired with coffee.  Most importantly, high quality L-theanine is safe, and effective.