Last updated: August 12, 2021

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If you are struggling to wind down or get good nights' sleep - in this article, we will be dealing with a food supplement that is becoming increasingly popular, L-Theanine.

L-Theanine is an amino acid that not only has a calming action, but also acts to protect the brain. Therefore, today it is possible to find several types of supplements with this substance. And we will show you what you should analyse to choose the best one.


  • With direct action on the central nervous system, L-theanine can improve sleep, concentration, relaxation and even protect the brain.
  • It is possible to find supplements with L-theanine together with other equally beneficial substances.
  • But attention must be paid to the dosage and, ideally, consumption should be under medical supervision.

The best L-Theanine: Our Picks

L-Theanine: Shopping Guide

Before you start taking a food supplement, it is crucial that you understand how the substance works and will react in your body. The same goes for L-Theanine. Although it is a natural and safe substance, it is necessary to pay attention to the composition of the different supplements with L-theanine, the form of use and the dosage.

To help you understand everything about L-Theanine, we have created this Shopping Guide. Check it out.

Menina deitada na cama com as pernas para cima, na parede.

L-theanine is a natural calming agent. (Source: Free-Photos /

What is L-Theanine?

Discovered in 1949, L-Theanine is an amino acid present in teas derived from Camellia sinensis, also known as white, green and black tea, and is also present in some mushrooms. L-Theanine is structurally similar with Glutamine and other neurotransmitters that are produced from it, and is known to have a positive action on our central nervous system. This is because it stimulates the production of alpha brainwave activity, which makes people feel calm and at the same time focused.

Mulher sentada no chão com as mãos no rosto.

Consuming l-theanine helps reduce stress and anxiety. (Source: Priscilla Du Preez/

In addition, L-theanine also reduces beta wave activity associated with nervousness and hyperactivity. Therefore, L-theanine is known to be effective in fighting stress and anxiety. But the main feature of L-theanine is actually to relax, but without the sedative effect.

Did you know that L-theanine is a very popular ingredient in functional foods and drinks in Japan? Japanese students often consume drinks and tablets fortified with L-theanine to decrease stress and anxiety, and increase alertness

What is L-Theanine used for and what are its benefits?

As we have seen, L-theanine has several functions in our body, all of which lead to a better quality of life. In order to understand more deeply how L-theanine can act in your life, check out the main benefits of this amino acid below:

Controls anxiety

As it acts directly on the nervous system, it triggers the following responses in the brain:

  • It affects the alpha waves associated with wakefulness and relaxation.
  • It increases levels of dopamine, the neurotransmitter that acts on emotions, mood and attention.
  • In some cases it can increase levels of serotonin, the 'happiness' neurotransmitter responsible for improving positive moods.
  • When combined with caffeine, it improves memory and reaction time.

Protects the Central Nervous System

Studies indicate that L-Theanine may also protect the brain. Protecting the cells of the Central Nervous System may have an important effect on diseases such as Alzheimer's disease.

Improves sleep

With L-theanine the body and mind are calmed, but the symptom of drowsiness does not occur. In other words, L-theanine is not responsible for inducing sleep. However, precisely because it induces relaxation, it is capable of acting on the quality of your sleep.

Research indicates that pre-sleep relaxation is extremely effective against insomnia, for example. No wonder L-theanine is prescribed by doctors as an alternative to improve hours of sleep.

Protects the liver

L-theanine is also known to act on the liver. Studies have shown that consumption of L-theanine was able to reduce blood alcohol levels and reverse alcohol-induced liver damage.

Works on the Cardiovascular System

Because it contains L-theanine, green and black tea are known to stimulate the production of nitric oxide. Nitric oxide dilates blood vessels, increasing the flow of blood. With this, nitric oxide accelerates muscle recovery and the gain of lean mass, strength and endurance. L-theanine appears to promote the formation of nitric oxide having beneficial protective effects on the cardiovascular system.

What is the difference between L-Theanine and other tranquillisers?

Some of the natural supplements that have similar action to L-theanine are: Gaba, Glutamine and Tryptophan. However, the ingestion of these supplements is only effective during sleep, so it is necessary to ingest them before bedtime.

L-theanine, on the other hand, promotes instant relaxation. But the main difference between L-theanine and other calming drugs is the fact that theanine has no sedative effect, which allows its use even in situations that require focus and attention, such as when studying or working.

L-Theanine and coffee: Why is this mixture good?

The relaxing properties of L-theanine also minimise the stimulating effects of coffee, energy drinks, soft drinks and chocolates, for example. But the fact is that L-theanine is often used in conjunction with caffeine.

This is because with the use of caffeine, for example, we become alert. But in the end it is possible to feel anxiety and stress effects, which can disturb the quality of your sleep. In some cases, the excessive use of coffee and energy drinks can even cause lack of attention, muscle tremors among other symptoms.

Pessoa escrevendo no caderno sobre mesa com notebook, celular e xícara de café.

Coffee is a stimulant which, combined with L-theanine, can have a more beneficial effect on health. (Source: Pixabay/

Therefore, the calming effect to L-Theanine reduces the negative effects of caffeine but at the same time, it acts in conjunction with the stimulant promoting focus and retention of information by the brain. However, before ingesting L-Theanine in conjunction with caffeine it is essential that you have medical monitoring.

What is the recommended dose of L-theanine?

L-theanine is fast-acting and the effects can be felt in around 30 minutes. In addition, the effects can last up to 12 hours. Therefore, it is not necessary to consume high doses. In general, L-theanine is effective in doses ranging from 50 mg to 200 mg. And even though L-theanine is safe, experts recommend not ingesting more than 600 mg within a six-hour period.

Can anyone use L-Theanine?

Although there are no studies that prove side effects or contraindications with the use of L-Theanine, it is common sense that this food supplement should not be consumed indiscriminately by everyone. Pregnant women, women who are breastfeeding and women under the age of 18 should not use this amino acid without medical advice and monitoring.

What are the advantages and disadvantages of L-Theanine?

There are many advantages of L-Theanine in our organism. The main one is that this amino acid induces relaxation without causing sleep. Furthermore, L-Theanine stimulates better quality sleep, reduces anxiety and decreases nervousness. The result of all these actions is that L-Theanine combats everyday stress, promoting an improvement in health and quality of life.

Mulher dormindo na cama.

Although it does not induce sleep, L-theanine promotes the relaxation necessary for a good night's sleep. (Source: bruce mars/

Not to mention that this amino acid also helps to improve focus, attention and memory, and even has the ability to decrease Pre Menstrual Tension (PMS). On the other hand, the downside is that not everyone can use this substance without medical supervision.

So, in general, check out the table below showing the main advantages and disadvantages of L-theanine.

  • Relaxes, calms down, improves sleep quality
  • Increases focus, concentration and improves memory
  • Decreases PMS symptoms
  • Non-addictive and harmless
  • Not everyone should use it

Purchase Criteria: How to compare L-Theanine supplements

When it comes to choosing the best L-theanine supplement, you need to take some factors that influence not only the price, but the effect you want to have on your health. Therefore, we suggest that you consider the following criteria before buying L-theanine.

From here on we will explain each of these topics in detail.

Tea or supplement

The first factor you should consider before you start taking L-Theanine is how you will do it. As we have seen, L-Theanine comes from tea, particularly green tea. However, according to experts one cup of green tea only has 1% of the recommended daily amount of L-Theanine. Therefore, if you are looking for a better result in reducing anxiety and fatigue, the ideal is to opt for L-Theanine supplements.

Prateleira de farmácia com vários potes de suplementos.

The food supplement of L-theanine is more efficient for those who need higher doses. (Source: moakets/

Isolated or compound

When it comes to choosing the best L-Theanine supplement, you also need to look at the composition of the product. This is because you can find supplements with L-Theanine both in isolated form and added to other compounds. Not infrequently, you will find supplements that have doses of caffeine, to increase concentration and improve memory. Another option is L-Theanine supplements mixed with passion flower, to boost the relaxation effect.


Another criterion you should check is the dosage recommended by the supplement manufacturer. You can opt for L-theanine supplements whose daily dosage can vary between 50 and 300 mg.


Also consider the amount of capsules that come in the bottle of the L-Theanin supplement. Take into account the period you intend to use it to buy the necessary.

(Featured image source: appledeng/