Perhaps you have already noticed L-theanine's popularity on the internet. You may find this nootropic in articles about mostly-liked supplements alongside Phenibut, Caffeine or Noopept. Moreover, L-theanine even has a few similarities compared with previous substances, though, some effects work differently. In this article, we will sum up all of the aspects that every user needs to know about the effects of L-theanine.


What is L-theanine?

L-theanine became a widely known supplement in 1949 when Japanese scientists extracted it from Gyokuro leaf, used for the preparation of a green tea. Our body does not produce L-theanine naturally, nor this substance is necessary to use. However, people tend to consider L-theanine supplement as a non-dietary amino acid, which provides such benefits that motivate people to add this supplement to their daily routine.

Despite the green tea, both black or white teas and some mushrooms are rich with L-theanine. To increase the content of L-theanine in such plants, manufacturers hide it from direct sun. The production of L-theanine begins in roots that synthesize the substance. Then the whole valuable content accumulates in leaves which are the main ingredient of the L-theanine beverage.

The structure of this substance has a few similarities to glutamine, which is an essential amino acid, responsible for the production of GABA and Glutamate. The taste of L-theanine reminds a broth and because of that it belongs to the group of savoury-tasting meals, also known as Umami. Some users have even reported that L-theanine has changed their taste perception by suppressing the taste of bitterness, for instance, in chocolate.


L-theanine benefits


The main benefit of L-theanine can be considered the improvement of focus. The studies made in 2012 and 2013 demonstrate how L-theanine, combined with Caffeine has improved alertness during mentally demanding tasks. Although the effect seems temporary and strikes sudden, the improvement is undeniable. If you have experienced the boom of Caffeine, this combination has even a more acute effect.



We have already tackled the enhancement of focus that L-theanine brings, but another feature of this supplement is so-called alert-calmness. The origins of it are related to L-theanine influence on our heart rate. Studies published in 2008 claim that after consuming L-theanine, patients showed the results of slower heart rate. Because of such a feature, we can consider L-theanine anxiety reductant supplement. Scientific findings show that in people facing anxiety-related disorders like ADHD or Schizophrenia the effects of L-theanine have reduced the symptoms of anxiety. Moreover, people who consumed L-theanine before particular mental challenges, have improved their focus and avoided tingling that usually is experienced just after the consumption of a higher dose of Caffeine.



The provision of calmness ensures not only wellness and the best mood but also has a beneficial effect on your sleeping condition. A recent study made in 2018 describes the impact of L-theanine on sleep and suggests that taking L-theanine for a longer period alleviates sleeping disorders and improves sleep quality. To be more specific, after a month or two of taking L-theanine supplement you should notice that falling asleep gets easier, your mood is more cheerful in the morning, and the energy does not abandon you during the whole day.

According to several studies, mixing L-theanine together with GABA supplement improves the sleeping quality more than taking it separately. Scientists have noticed that a dosage of 100 mg GABA and 20 mg L-theanine decreases sleep latency and extends sleeping time. If the option of GABA supplement does not suit you, you may also try to mix L-theanine with Melatonin supplement.



L-theanine has some anti-inflammatory properties that could be advantageous to your immune system. Consuming L-theanine for a longer period builds the protection from catching a cold or other illnesses and infections. Some more specific research was made that proves L-theanine’s capability to protect the upper respiratory tract and intestinal tract from infections and damage.

Let’s go back to the already mentioned Umami flavour. Scientists tried to elucidate the hypothesis of L-theanine’s impact on weight loss. What they did find is the same Umami taste which might reduce people’s appetite and help to lose some unwanted kilograms. This supplement can be even a best tool to get rid of obesity and regulate your regular body weight.



To provide you calmness, L-theanine alleviates a heart rate, which leads to decreased blood pressure as well. High blood pressure often becomes a cause of severe heart malaise, such as stroke. Besides, some people are likely to experience a sudden increase in pressure when facing stressful situations, so what L-theanine does is the prevention of such occurrences.



A few studies regarding the impact on cancer treatment showed significant results. According to the research made in 2011, L-theanine beneficially affects chemotherapy drugs, especially doxorubicin. A few speculations appeared about the potent influence during the whole cancer treatment, but there is no clear research made. However, scientists have noticed that people who often drink green tea have a lower risk of cancer.



L-theanine has a feature which aids people with Sinusitis. Scientists have reported that L-theanine activates Cilia, an organelle that assists in clearing up mucus and reducing infection in the nose. So, the major role of L-theanine is to fasten the whole healing process.



Because of the antioxidant effects, L-theanine can aid in the recovery process from alcoholism by improving the condition of damaged liver. An excessive alcohol consumption often leads to a higher production of free radicals, which causes a big harm not only to the liver, but to the whole health condition. What L-theanine does is the neutralization of these free radicals and in such a way protects your immune system and organs from damage.


Even though L-theanine provides a great benefits regarding issues caused by alcohol, it is still not known what should be the exact dosage for people facing alcohol withdrawal symptoms


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Is L-theanine safe?

According to the Food and Drug Administration (FDA), L-theanine is considered as possibly safe. However, some users have reported some adverse effects, which could appear because of several reasons, but the primary one is the overdose. We always try to emphasize the need to carefully follow the dosage instructions and be patient about the occurrence of potent beneficial effects.


L-theanine side effects

Scientists consider L-theanine as a possible safe nootropic that usually causes no side effects. But to avoid or prevent any inconvenience, be aware of the side effects that can occur. Among the benefits, we have mentioned the feature to decrease the blood pressure, so if you are facing hypotension or sometimes experiencing reduced blood pressure, avoid taking L-theanine to prevent worsening.

Bear in mind that L-theanine may interact with other medications, especially with supplements that affect blood pressure or used for anxiety treatment. Besides, L-theanine reacts a bit differently with other stimulants and supplements with caffeine. It does not mean side effects appearing, but you might experience particular effects more sharply. To avoid any surprises, talk to your doctor before using L-theanine.

It is highly not recommended to take L-theanine for pregnant or breast-feeding women and children. Among possible side effects, we could mention nausea, dizziness, anxiety or stomach ache.


L-theanine dosage

It is necessary to follow the proper daily dosage, which varies from 100 mg to 400 mg. Since everyone has diverse immune systems and biological synchrony, every individual is free to determine the exact dosage depending on their health. We always recommend to start with the lowest possible dosage and then gradually raise it till you find what fits you the most.

If you are going to combine L-theanine and Caffeine together, the dosage should be about 12-100 mg of L-theanine and 30-100 mg of Caffeine. However, always follow the label and dosage instructions.


Text Author:
Kay Svegler
Communications, PR, American Studies, University of Leipzig
Journalist and freelance writer (e.g. Süddeutsche Zeitung, BILD, MDR etc.)
Former Senior PR Manager for Fischer Appelt, Sustainability and Diversity Manager for DKB