Tea 101
What Is Theanine In Tea – How It Works & What It Does In Our Bodies

What Is Theanine In Tea – How It Works & What It Does In Our Bodies

Tea has been praised with having many health benefits. Why does it get this attention? Because it’s true! Tea contains many unique chemistries that interact with our bodies and not only make us feel healthy, but also promote longevity, cardiovascular health, brain health and more!

This article is going to dive deep into one of those specialized tea components. That compound is theanine! Let’s explore what is theanine in tea, the science behind how it works, how it reacts with our bodies, side effects and best source to get it from.

Theanine…What The Heck Is It & How Does It Work?!

Theanine, also known as L-theanine, is a non-protein nonessential amino acid. There are 20 amino acids used as the building blocks of protein, but a non-protein amino acid is not used for proteins. It does still get used in many other cool ways!

Specifically, L-theanine is a special amino acid found naturally in tea and some mushrooms. It acts similarly to glutamine, another more popular and necessary amino acids.


Theanine acts by elevating GABA, serotonin and dopamine levels in the brain. These chemicals are known to aid in regulating moods as well as emotions, concentration and sleep. L-theanine also inhibits chemicals released in the brain that cause stress and anxiety.

Finally, our brains produce these wave lengths that aid in relaxation, focus, creativity, energy, and more. L-theanine enhances alpha wave lengths which are associated with a state of “wakeful relaxation”. This can be compared to that state you feel when daydreaming and meditating!

Are There Health Benefits?

There are! People have taken L-theanine supplements for many reasons including to unwind, ease stress, and relaxation without sleepiness. Why take the supplements when tea has it naturally?! Let’s explore more benefits.

Increased Mental Performance

Mental performance here can be defined as the ability to recall information. Studies of L-theanine and testing scores have been done and shown a positive correlation with students who did take L-theanine prior to an exam and scoring better than those who did not (1).

Look at all those wave lengths!

Greater Relaxation

One of the main benefits of this chemical is that relaxation state. This can be compared to the state we feel naturally from breathing techniques and meditation, but if you are not familiar with those techniques, tea is a great way to feel it too!

A few studies have shown the benefits of relaxation from L-theanine. One of which took 104 participants who struggle with stress and anxiety in situations which trigger these feelings. They recorded that those who used the L-theanine reduced those feelings (2)!

Clearer Focus

The interesting thing about tea is that it also contains caffeine, and caffeine and L-theanine are a match made in heaven! A study found that the combo of L-theanine and caffeine, at a 96mg to 40mg respective ratio, aided in focus on demanding tasks (3).

Improved Immunity

Our immunity may be improved by increasing our theanine intake! Our bodies immune system is predominantly made up of the small intestine. L-theanine actually decreases inflammation in that intestinal tract. L-theanine triggers our bodies to respond on a minor scale as our immune system would (4). This builds up strength in the immune system!

Possible Cancer Prevention

There have been a few studies that have shown benefits of the combination of chemotherapy and L-theanine (5). Another study showed women with ovarian cancer who drank green tea daily lived longer than those who did not (6). One other study showed that drinking green tea daily may have lowered pancreatic cancer development rates by up to 37% (7). While there is not enough data yet to make any firm claims, all this research has sparked many more people to dig deeper!

Deeper Sleeping Patterns

Put your deep sleep game face on!

L-theanine is great for promoting relaxation, this will definitely aid in sleep. Research found that doses of 250mg to 400mg of L-theanine showed greater sleeping patterns in participants than those who did not intake L-theanine (8). There are many other studies that indicate the same type of conclusion!


There are even a few other potential benefits such as decreasing blood pressure, delaying Alzheimer’s disease, aiding medication used for schizophrenia, and sinus pressure relief!

Should I Be Concerned About It?

Generally speaking, L-theanine is well tolerated by the majority of people! The lethal dosing rate is unknown as it has been studied up to 4000mg/kg bw/day and still the mice were healthy (9). For reference, one cup of matcha (~2g of powder) contains less than 40mg of L-theanine.

People who should consult a physician before use include: pregnant women, people with low blood pressure and children.

The largest side effect of taking L-theanine by tea is consuming this on an empty stomach and getting a slight stomachache or headache.

What Tea’s Have This Compound?

Most of the teas that come from the Camellia sinensis plant (black, green, oolong, white and pu’erh) contain L-theanine! Pu’erh unfortunately does not :(. The recommended daily intake is anywhere from 100 – 400 mg/day. Certain teas contain higher levels. Below lists those average concentrations.

  • Green Tea: 6.56 mg/g
  • Black Tea: 5.13 mg/g
  • Oolong Tea: 6.09 mg/g
  • White Tea: 6.26 mg/g
  • Pu’erh Tea: 0 mg/g
  • Matcha: 19.5 mg/g

(Note* All the numbers above are recorded in milligram of L-theanine per gram of tea (10)).

Is Theanine Right For Me?

L-theanine is a natural nonessential amino acid found in tea. It functions in our brain by increasing GABA, dopamine and serotonin levels. All of these help improve relaxation, focus, sleep, blood pressure, immunity and more! Certain tea contains higher levels of this amino acid and the recommended daily intake is 100 – 400 mg/day.

Ultimately, if you are interested in trying out tea for the benefits of L-theanine try it out! Listen to you body and see how it feels for you.

Click on the image to try out Matcha Kari’s matcha!

To get the most out of your cup of tea, try matcha! For the highest quality and most authentic kind, try Matcha Kari’s matcha by clicking here! Matcha Kari sources organic tea leaves perfect for matcha and it shows in the taste!

Let me know in the comments if this answers “What is Theanine in tea?” and what you liked about this post!


  1. https://pitjournal.unc.edu/article/improving-college-exam-performance-l-theanine-and-caffeine
  2. https://www.journals.elsevier.com/journal-of-nutrition-and-intermediary-metabolism
  3. https://www.tandfonline.com/doi/abs/10.1179/147683010X12611460764840
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772912/
  5. https://link.springer.com/article/10.1007/s13205-011-0036-2
  6. https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.20456
  7. https://www.sciencedirect.com/science/article/pii/S1877782112001130?via=ihub
  8. https://www.mdpi.com/2306-5710/2/2/13/htm
  9. https://www.ncbi.nlm.nih.gov/pubmed/16759779
  10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4787341/

4 thoughts on “What Is Theanine In Tea – How It Works & What It Does In Our Bodies

    • Author gravatar

      Once again your post amazes! I had no idea that the benefits could be so vast in a simple cup of tea! Thanks for continuing to make my tea drinking experience a joy.

      • Author gravatar

        Mia, thank you for the comment! I love to hear these are spreading joy to your tea drinking experience. I want to educate people about what they are putting into the bodies so they can enjoy tea and other things that much more!

    • Author gravatar

      Dear Vince,
      I find the list of L-Theanine levels in each tea very interesting and helpful! Do you know if there is correlation between the oxidation level of a tea and how much L-Theanine it contains? Pu’erh having none, is this because of its fermentation? Very informative article!

      • Author gravatar

        Cierra, thank you for the questions! First off, it is important to note that those theanine levels are averages across the tea spectrum. The big takeaway from that is that a cup of black, white, oolong and green tea will roughly give you the same amount of L-theanine. Pu’erh unfortunately won’t give you the awesomeness of theanine (yes that is due to the fermentation process). Matcha though is the way to go! By consuming the whole leaf in matcha, you are able to absorb about 3 times as much than a normal cup of green tea. That is why matcha is the (self imposed) mascot of L-theanine and tea!

        You are correct, there is a correlation between oxidation and L-theanine! Generally speaking, the further the tea is oxidized the lower the levels of L-theanine and other antioxidants . This is a generalization however! There are studies that have found a cup of black tea with levels up to 15mg/g! Other factors that could effect the L-theanine concentration includes steep time, steep temperature, addition of milk to your tea, and tea quality.

        Let me know if there are any other questions!

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