L-theanine Health Benefits

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Introduction to L-Theanine

Some say L-Theanine is ‘meditation in a capsule’ or in a bag of green tea. The use of green tea for therapeutic benefits goes back a long way in China to almost 5,000 years ago. The Japanese are so into their green tea they have a ceremony for it and a tea house specifically for green tea. The reason being is L-Theanine and the l-theanine health benefits are many.

We drink green tea to make ourselves calm and content and it works. Green tea is now being consumed around the world for its calming effect. Several scientific studies have and are continuing to back up with clear evidence of the health benefits of green tea with their focus being on L-theanine. L-theanine is a calming amino acid that promotes alpha-wave brain production.

In this picture you can see there are five brain waves; GAMMA, BETA, ALPHA, THETA, and DELTA.  Each one corresponds to a different state of awareness.

L-theanine causes an increase in ALPHA wave activity, the brainwave state associated with relaxation and attention.

L-theanine health benefits

It is also a recognized anxiolytic (anxiety reducer) that has been shown to improve our quality of sleep and improve our mental and physical stress symptoms by producing a feeling of calmness, reduced heart rate and blood pressure.

This increase in alpha- waves promote relaxation without drowsiness or sedation. Alpha brain-wave production also happens during deep meditation, when all sensory inputs are minimized and our mind is generally clear of unwanted thoughts or distractions. Interestingly, stimulating alpha waves has also been shown to boost creativity and alleviate depression.

Benefits of L-Theanine

Preliminary research into L-theanine suggests it may increase our mood, enhance our brain function, and calm our response to stress and anxiety. Here’s a look at some:

Reduces Anxiety

A 2016 study (1) has shown that L-theanine may reduce anxiety. A group of healthy volunteer were asked to consume a drink that contained 200 mg of the supplement. Half were given a placebo. After an hour their response to a cognitive stressor was tested and was found to be significantly reduced in those who ingested the drink containing L-theanine. Those who took the placebo had a normal response.

Another (2) suggested that taking L-theanine regular and daily decreases subjective stress and saliva levels of a-amylase in undergraduate students in a stressful situation. A-amylase is an enzyme that gets released in response to stress.

Benefits Sleep and Sleep Qualityl-theanine health benefits

L-theanine has been found to improve our sleep quality including children suffering the effects of ADHD. It is not surprising that L-theanine is shown to help sleep knowing that is the calming factor in the popular green tea. It promotes a relaxing pre-bedtime but does not create the drowsy sedation effect associated with sleep aids and anxiolytics.

A study in Japan gave a group of volunteers 200mg of L-theanine per day and then analyzed and recorded their sleep patterns using wearable devices. The result was that sleep quality, recovery from exhaustion, and a feeling of being refreshed were increased by L-theanine.

When looking at children suffering from ADHD we see that L-theanine may improve their quality of sleep. A study was conducted on a group of boys aged 8-12 who were given 400mg a day and found that L-theanine was very effective and safe, an even more important factor when dealing with children.

A preliminary study (3) examined the effects of what low-caffeine green tea has on sleep quality. Green tea that contains caffeine is very destructive on the desired effect of green tea. The effects of L-theanine are counteracted by caffeine. After consuming low-caffeine green tea every day for seven days, saliva alpha-amylase levels were significantly lower in those who drank the low-caffeine green tea than in those who consumed the standard green tea. Sleep quality was improved by those drinking caffeine-free green tea.

Improving our Mood

L-theanine helps to improve the production of GABA (an inhibitory relaxing neurotransmitter) and therefore it has a key role in mood support. GABA is important for nervous system function and is widely used as a natural supplement to decrease anxiety, promote sleep, and improve our mood. It also helps boost dopamine and serotonin levels.

Attention and Working Memory

Green tea consumption appeared to enhance performance on a test of working memory (short-term memory) by increasing the connectivity between the frontal and parietal lobes during working memory processing. This is very interesting in that the frontal lobe is responsible for executive function and the parietal lobe is responsible for sensory input. Being as L-theanine has a similar makeup to glutamate a neurotransmitter related to memory.

In a 2010 study (4), it suggests that combining L-theanine and caffeine may help to improve cognitive performance.

In this study, 44 young healthy adults were either given a mix of L-theanine and caffeine just before they had to tackle a demanding cognitive task. The results showed that combining L-theanine and caffeine does significantly improve accuracy and alertness as well and helps us to increase focus during the task.

An Excellent Antioxidant

l-theanine can search out free radicals in the body that contribute to organ or tissue breakdown, inflammation, degeneration, and even help reduce the effects of ageing. Its antioxidant properties are the reason daily consumption extended longevity in ancient China.

There are a number of studies that show this.  In one study, l-theanine had strong enough antioxidant action to even protect against liver damage. (5) In another, it was shown to be powerful enough to heal ulcers.

L-theanine and Weight Loss

Animal research has shown promising results so far using L-theanine as a weight loss supplement. The research showed mice fed green tea powder containing L-theanine and caffeine appeared to prevent the mice from gaining weight.

Counteracts the Effects of Caffeine

A recent 2015 study even proved this, showing that l-theanine and caffeine are taken together to reduce high blood pressure and nervousness compared to caffeine taken alone.

This may help explain why green tea, even though it has much higher levels of caffeine than coffee, gives people a much smoother ride to an alertness boost than coffee does.

As such, when l-theanine is taken together with caffeine, one can experience a stimulated, energy-boosting effect without unwanted anxiety and jumpiness.

Cardiovascular Healthl-theanine health benefits

Theanine may help to prevent blood pressure spikes as a result of the stress response by regulating nitric oxide. What is Nitric Oxide? It is a molecule our bodies make to assist in cell communication, regulate our blood pressure and does the by vasodilation, reduction of inflammation, supporting the immune system and improves our sleep quality. Nitric oxide is produced by the endothelium of our arteries which help relax the narrowed blood vessels which in turn increases blood flow and therefore oxygen flow. If we have an increased amount of nitric oxide, it can protect our arteries from clots, heart attacks (MI), and stroke (CVA)

Better immunity

Research on immunity shows us that L-theanine may be able to improve our immune system.  A study found that it could help lower the risk of upper respiratory tract infections.

In another study, L-theanine was shown to help lower inflammation in the intestinal tract, but more research is needed to confirm this.

Some more research suggests that L-theanine may improve the function of the body’s immune system. One study published in the journal Beverages found that L-theanine could help decrease the incidence of upper respiratory tract infections. 6)

Another study found that L-theanine could help improve inflammation in the intestinal tract. However, more research is needed to confirm and expand on these findings. (7)

Blood Pressure

It seems L-theanine may help lower blood pressure for those with stress-induced hypertension.  In 2012 a study was performed observing people who experience high blood pressure when in stressful situations.

They found L-theanine did, in fact, control blood pressure for these people when in a stressful situation. (8)


L-Theanine and Caffeine for Hangover

The combination of L-theanine and caffeine is also very good for the symptoms of a hangover.  You can read more in my article on The Best Nootropics for Hangover!

L-Theanine Supplements or Tea

There are two main ways to get your l-theanine.  Drinking tea or as a supplement.

There haven’t been enough studies on how effective the theanine supplements are on us humans so all we know is that drinking it from tea is a great way to get it in your system.(9)

However, you will get only about 25 mg of l-theanine from a cup of tea, while most supplements contain 200 mg per serving.

If you take L-theanine supplements for anxiety, high blood pressure, insomnia, and general stress relief these supplements are considered very safe. (10)

Side Effects of L-theanine

Right now there seem to be no side effects to taking l-theanine regularly. That said, long term studies that can determine this has not been done or haven’t concluded.l-theanine health benefits in green tea

Green tea is consumed on a regular basis by millions of people worldwide and is considered very safe.

If you drink caffeinated green tea you won’t experience the effects of l-theanine as the caffeine counteracts this. Instead, you will feel the side effects of caffeine such as irritability, heartburn, rapid heart rate, headache and insomnia.

If you are taking other sedatives, medications to lower lipids, or chemotherapy medication, you should definitely consult with your physician before taking l-theanine.

According to Memorial Sloan Kettering Cancer Center, the polyphenol EGCG found in green tea can actually reduce the efficacy of some chemotherapy drugs, such as bortezomib.

For that reason, it’s very important for those taking chemotherapy drugs to consult their doctors before drinking large amounts of green tea as part of their treatment plan.

A few adverse reactions reported in studies using tea extracts include headache, dizziness, and digestive upset. (11)

Use l-theanine with caution if you take a high blood pressure medication since it can decrease your blood pressure. (12)

If you are pregnant, are lactating you should not take l-theanine.

Although l-theanine has shown promise in children with ADHD, I always caution when giving supplements to children. Consult your children’s doctor before giving l-theanine.

Where to Buy L-Theanine

L-theanine is widely available to purchase online, L-theanine supplements are sold in many natural-food stores and in stores specializing in dietary supplements however quality may vary.

You can find good quality l-theanine here at Pure Nootropics

Of course, it is also found in green tea. Although the content varies from brand to brand.


You can enhance your overall health by drinking green tea on a regular basis and I encourage you to do so.

L-theanine is proven to lessen anxiety, improve sleep, enhance our cognition, memory, and focus, and protect our brain. Research also shows that it can help reduce and may even prevent stress-related hypertension, and it may be a valuable adjunct therapy for cancer patients.

This great natural supplement is also a key ingredient in the highly touted nootropic stack Onnit Alpha Brain

L-theanine can also be found in the nootropic stack Genius Joy I have reviewed here.

In fact, 200mg of l-theanine is in one of the best nootropic stacks today, Qualia

If you’re considering the use of L-theanine supplements with any of the conditions listed in the sided effects section of this article, please consult with your physician.

14 thoughts on “L-theanine Health Benefits”

  1. L-Theanine definitely sounds like something that I need.  The benefits seems to be many, and all of which I can benefit from for sure.  I am not a tea drinker, so I cannot see myself drinking green tea.  I can see myself taking the supplement, that would be the best choice for me.  Thanks for the great and in-depth review of L-Theanine.

    • I’m not much of a tea drinker although i feel good after drinking green tea so I do a couple of times a week.

      The supplements are very easy to find, but the best brands are online.

  2. Stew,

    I have always heard that green tea is actually good for you, but with your article I now see that if it contains the caffeine then it does not hold the effective benefits that it should.  My grandson is on medication for ADHD and I am not a person who is into medications with all the chemicals preferring natural treatments over them at all times.  I am going to look around and try to find the green tea without the caffeine that can be used for him.  I will be trying this out before suggesting he use it for my own anxiety issues.  Thank you so much for this very useful information more people need to know about these natural treatments and stop giving their children chemicals to solve issues.


  3. I am just so lazy to look up, now I am having my coffee and finally know what is L-Theanine. I have seen it everywhere in the heath food stores! I do drink green tea regularly, my favorite one is genmai cha and matcha with Japanese sweets like mochi yummy. So many benefits that I wan’t even aware of. I have a question, when do you think you have too much of L-Theanine? I know the side effects of caffeine very well, since I am a coffee addict, I tend to be very sweaty and have heartburns. Or maybe too much of it is not as bad? What if you already drinking green tea and take the L-Theanine at the same time? Just curious, I love supplements lol. Good read.

    Happy Holidays

    • You won’t take too much L-theanine by drinking no supplementing.  It is very safe.  There are no side effects like caffeine either.  When drinking green tea make sure that it contains no caffeine or the caffeine will counteract the  effect of L-theanine.

  4. hello stew,  All I can say is wow. I have heard of L-theanine but I had no idea of the effect that it had mentally and physically. Your post is very informative. I actually suffer from adult ADHD. And this post has helped me drastically I have trouble sleeping because of my ADHD. I can’t wait to purchase L-theanine. It has so many positive effects. I will especially help on the memory side of things now that I am into online marketing my brain has to be fresh everyday when I wake up and start work. The sounds like such a great product thank you so much for sharing this post I wish you well in your endeavors. And I will definitely get back in comment on your post when I try this. I’ve been looking so long for a non medication sleep aid that doesn’t cause me to get jumpy from side effects. Hopefully I have found that product. If I may ask a quick question how long have you been using this product? And are the effects long term as well as short-term because I’ve had products that work for the first week or so then they give out and no longer work. Thank you again for this post since early, your friend Mike Trueblood.

    • Well, thank you Miket224.  I am glad you see an alternative to the regular sleep aids.  Decaf green tea is a great start, but you can get the L-theanine easily as well.

      Hope to hear from you again.

  5. It is very transparent and detailed, so it does not go too far into details to just confuse it even more. Excellent information, I think I only used creatine from supplements from list, I can agree that it is excellent. I support the use of supplements in normal quantities, especially if they are of natural origin.

    Best regards ,

    MMA Store

    • Creatine is a great proven supplement for sure.  I use it too.  L-theanine is another proven nootropic used world wide with great results across the board.

  6. Hi Stew, I have heard a lot about green tea. I tried drinking it once but it’s taste put me off. Reading about it in your post is very educational. It’s interesting to know that L-theanine in green tea aids a good sleep, calms the mind and reduces anxiety and it does all this with no known side effect. I am definitely going to give green tea a try again!

  7. This is a great article about L-theanine.  A lot of the great herbs goes back to China and Japan, it often takes a couple of years or more for the rest of the nation to figure out what they already know.  We could all use less anxiety, good sleep and better moods.  Health, weight loss and working memory are great benifits to some who is getting a little older like me.  

    • You’re right.  They take a while before people here catch on.  Supplements are often laughed at when they certainly shouldn’t be.

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