The Most Full L-Theanine Review

l theanine review

If you have never heard of L-Theanine and become interested in supplements enhancing your mood, concentration, and focus, you will be surprised that you probably already get one while drinking green tea.

L-Theanine is a natural amino acid called L-Glutamic acid or gamma-glutamylethylamide. This compound was isolated in 1949 in Green tea (in particular, the primary compound – Camellia Sinensis). L-Theanine is also presented in certain types of mushrooms.

Chemically this supplement is similar to the formula of another amino acid – Tryptophan, and analog of glutamate and glutamine.

In its turn, L-Glutamic acid is a precursor of Serotonin – a neurotransmitter responsible for wakefulness schedule and sleep pattern, and therefore L-Theanine’s main effect is in increasing the level of Serotonin.

The first studies which provided complete research on the beneficial effects of L-Theanine were conducted in 1999 (Food Science and Technology), read on Pubmed.

Patients were given the dose which had become a standard one after it.

All nootropics have a similar mechanism of action. Though not all aspects of this mechanism are well understood, the main resemblance is an ability of nootropics, in particular, L-Theanine, to cross over the BBB (blood-barrier and) coming directly to CNS (central nervous system).

Such ability is a key factor for quick absorption into the bloodstream, fast response, and direct transfer of elements to the brain.

This compound reaches four areas of neurotransmitters regulating arousal reaction of CNS, stress, pleasure, and attention. These are Serotonin, Dopamine, GABA, and Norepinephrine.

But why is this mechanism so important?

First of all, the ability to cross BBB fast allows to save time and directly target required areas for reducing anxiety, preclude restlessness, stress, or improving motivation, energy, and concentration.

It happens because L-Theanine is able to prevent overactivity of the brain and balance neurochemicals for a good mental performance.

By stabilizing the brain’s excitation state, this supplement provides such benefits as a feeling of calmness, relaxation, to tranquility.

But not only is Serotonin affected by L-Theanine, but this supplement also involves Dopamine and Norepinephrine.
In fact, Dopamine and Norepinephrine are those neurotransmitters that promote a positive attitude, good mood, and motivation.

L-Theanine is one of the supplements which offers a wide range of focus boosting and anxiety-relieving qualities. It has been used for years as a commercial product specifically aimed to improve concentration, focus, mood, and memory.

Mental performance is highly increased by L-Theanine as your brain gets more energy, oxygen, and good blood flow for persistently high performance.

As a result of taking L-Theanine, users perceive a great sense of focus and concentration.

That supports a high level of performance which is required during studies, exams, and stressful work.

Mood disbalances have been often the reason for low performance, motivation, drowsiness, and many others which are effectively cured by L-Theanine.

L-Theanine is quite often recommended by users and considered to be safe for regular use.

Anxiety itself could be either an independent disorder caused by different neurological deficits or a symptom of depression.

That is why some users are specifically looking for an effective anti-anxiety drug.
In this respect, L-Theanine is one of those drugs.

Same as Ginkgo Biloba, L-Theanine was used for thousands of years and initially was started to be used in Chinese medicine.

Unlike recently produced nootropics, L-Theanine was tested for a long time in practical aspects of its usage like side effects, tolerance concerns, safety, interactions with other medications, etc.

These aspects are well-documented and experienced for a great while. This fact makes this supplement a “no surprise” herbal remedy, fully natural and safe for children and adults.

It’s also worth mentioning that L-Theanine can be an independent agent for dealing with symptoms of ADHD, stress, sleep problems.

Or as a complementary remedy used in a lower dose for normalizing your daily regime.

The detailed description of L-Theanine benefits below will help you to find a required intended use.

Summary: L-Theanine is amino-acid structurally analog similar to the excitatory neurotransmitter glutamate. It’s able to cross the BBB (blood-brain barrier) and it shows an ability to reduce mental and physical stress, anxiety, improve cognition and boost mood especially if taken with caffeine.


















  • Cognitive enhancement (with coffeine)

  • Stress relief

  • Mood boost

  • Reduce anxiety

  • May help with sleep (quite weakly)

  • May boost immune system


  • A few side effects like: low blood pressure, diarrhea, dizziness 

  • It may not be stacked well with a few other nootropics


In 2004 Harvard Medical School reported on important L-Theanine benefits of the immune system boost and promoting freeze-thaw resistance.

Today this nootropic is widely used to improve mental performance, focus, concentration, mood, energy level, motivation along with relaxation and calmness.

The benefits of L-Theanine are directly related to its mechanism of action. In two words, L-Theanine blocks neurotransmitters (L-Glutamic acid) responsible for the arousal of CNS.

Being blocked, this acid is not able to send many signals to activate stress reactions.

So L-Theanine reduces the signal of neurotransmitters and slows down all excitatory processes and reactions in the brain.

l-theanine review


Visually it manifests itself in a feeling of calm, tranquility, relaxation, decreasing heart rate and blood pressure, preventing seizures if any, and many others.

This mechanism also exhibits the neuroprotective effect of L-Theanine as decreased stimulation of synaptic receptors which does not allow them to “burn” and oxygenate brain tissue for better performance.

This supplement brings a great synergetic effect on muscle and mental performance.

It also has an impact on the cardiovascular system by not only fighting hypertension but also activating the production of nitric oxide inside the walls of blood vessels, which helps to open blood vessels.

According to users’ reports, L-Theanine boosts alpha brain waves.

But what does it actually mean? As per scientists, these are electrical impulses normally produced in the brain and associated with periods of intensive brain activity and concentration.

Alpha waves are an important factor that makes you feel relaxed, calm, and a sort of stimulant bringing forth clarity of mind, inspiration, creativity, motivation, and incredible productivity.

Another important benefit of this natural supplement was found to be helpful for chemotherapy patients

According to studies in this area, L-Theanine demonstrated an ability to keep safe healthy cells from unhealthy ones and thereby poison of chemotherapy brings no harm to healthy cells and promotes their normal work.

This began to take a new meaning when it comes to side effects of chemotherapy which are very heavy ones and in some cases may lead to death.

L-Theanine eases damage of those side effects reducing its negative impact.

Other beneficial effects of L-Theanine include enhancement of energy levels, mood, cognitive performance, and motivation by affecting Dopamine, fights with anxiety and stress.

L-Theanine stimulates the growth of nerves by producing proteins for them.
Also, the capability to produce an anti-oxidant effect is one of the well-known. It prevents the oxidation of LDL cholesterol.

And of course, an optimistic mood and cheerful outlook on life are the main benefits for those who use L-Theanine in baseline dose for improving overall well-being.

How It Works

L-Theanine’a mechanism of action is mainly concentrated around two factors.

First of all, it binds to the receptors of glutamate and blocks them, it is possible because L-Theanine has almost the same molecular structure as glutamate. This, in its turn, provides an inhibitory effect.

Also, L-Theanine increases the synthesis of GABA (relaxing neurotransmitter) so that also does the trick resulting in calming and relaxing effects.


l-theanine review
Note: We gather data from different social media sources.


l-theanine review

Note: The data is based on users’ feedbacks across different social media sources.

People’s experience

l-theanine review

Note: The data is based on users’ feedbacks across different social media sources.


l-theanine review
Business photo created by tirachardz –

Normally L-Theanine should be taken in the dosage of 100-200mg once or twice daily.

Researches also indicate the fact that many people don’t obtain any adverse effects at even much higher doses, but exceeding the regular dosage is still not recommended.

Note: L-Theanine can be used along with caffeine (recommended).

Side Effects

L-Theanine is potentially safe when taken orally in recommended doses.

A few adverse reactions were noticed by studies including headache, dizziness, and GI symptoms.

Interactions And Contraindications

L-Theanine should be taken in moderation with the following types of medications (please consult your health care provider prior to usage):

  • Antihypertensive drugs (for high blood pressure)
  • Stimulant drugs (diethylpropion, epinephrine, phentermine)

Available Forms

There are a few forms you can find L-Theanine available for purchase in the market:

  • Tablets
  • Capsules
  • Liquid
  • Powder


The common stacks for L-Theanine are:

  • L-Theanine + Caffeine
  • L-Theanine + Fish Oil
  • L-Theanine + AlphaGPC
  • L-Theanine + 5-HTP
  • L-Theanine + Green Tea Extract

Medical Uses

As was already mentioned in the overview section L-Theanine is considered to be an anxiety/stress relief agent which is able to boost GABA and other brain calming chemicals.

Not only does L-Theanine leverage the level of GABA, but it also facilitates an increase of serotonin and dopamine in the brain.

Studies show that L-Theanine enhances alpha brain waves which are associated with a state of “wakeful relaxation” – a state of mind when meditating or daydreaming.

That actually brings one of the most important benefits of L-Theanine – being relaxed without sedation.

So it could be a good solution for ones willing to relax without being fatigued or sleepy.

It could also be potentially helpful in fighting off some sleep disorders, but it should not be considered as the first-line treatment in such cases.

Legal Status

L-Theanine is supplied as a dietary supplement and can be easily bought over the counter in most countries.

In the US L-Theanine has been granted GRAS status in doses up to 250 mg by FDA.

Where To Buy

We strongly recommend buying L-Theanine only from reliable online retailers.


An average price for a pack of L-Theanine if buying online is $12 depending on a form (pills/tabs/powder etc) and the brand name.

Almost the same situation is applicable to offline retailers such as Walmart, where you can buy L-Theanine for as cheap as $8-$10 per bottle containing 250 capsules.


Supplements and drugs with similar effects are listed below:


Q: What is the best time of the day to take L-Theanine?

A: Many users report that the best time for taking L-Theanine in the morning and the middle of the day.

Q: Can you take L-Theanine with antidepressants?

A: Yes you can. There are no contraindications for this.

Q: Does L-Theanine help with sleep?

A: Partly. L-Theanine does not provide a direct sedative effect rather it helps to gain so-called “wakeful relaxation”, but the relaxation itself can indirectly help you to fall asleep.

Q: Does L-Theanine increase dopamine?

A: Yes.

Q: How much L-Theanine is safe to take?

A: According to the official studies L-Theanine is non-toxic to mammals, so it’s hard to say precisely what the safest max dosage for a patient is.

Many people claim they take 800+ mg of L-Theanine daily with no negative consequences.

But you should take into account your particular condition and needs, so normally it’s not recommended to exceed a regular dose of 100-200mg once or twice daily.

Bottom Line

Being an amino-acid analog of the proteinogenic amino acid L-glutamate L-Theanine is effective in dealing with stress and anxiety.

Its relaxation properties along with an ability to raise levels of dopamine, serotonin, and GABA coupled with lack of the sedation effect makes this supplement stand out from many other modern nootropics.

The fact that L-Theanine is totally safe and non-toxic gives that nootropic even more advantages compared to other treatments.

So if you face any of the conditions relevant to L-Theanine’s use cases, you should definitely give it a try by taking it solely or in a stack with caffeine or other eligible nootropics.

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