Theanine: Everything You Need To Know

Theanine: Everything You Need To Know

I often get asked what supplements I take on a regular basis.  The answer?

Not many.

Don’t get me wrong…

I’ve experimented with TONS of supplements and some have earned a spot in my daily supplementation regimen, but the truth is most supplements are pretty useless.

One supplement that has both a ton of research supporting it’s use for a multitude of reasons–not to mention my own anecdotal support as  well–is Theanine.

You may have heard of it before, but if you’re like most people, you have no idea what it is or what it’s genuinely capable of as a supplement.

Well, not to worry…

By the end of this article, you’ll be an expert on Theanine!

We’ll cover everything, including:

  • What it is
  • How it works
  • The benefits
  • Dosing
  • Sources

And a whole lot more.

So, if you’re ready to learn how this unique nutrient can benefit you, let’s get right into it…

What Is Theanine?

What Is Theanine

Theanine, typically supplemented in the form of L-Theanine, is a non-dietary amino acid found almost exclusively in Green Tea.

To be more specific, Theanine has been identified in the following species:

  • Camellia sinensis (leaves used to make black and green tea)
  • Camellia japonica (flowering plant)
  • Xerocomus badius (a mushroom)

For supplement purposes, it’s generally extracted from tea leaves (Camellia sinensis) since the world-wide demand for tea is already so high and the leaves a relatively inexpensive to grow, harvest, and process.

It’s estimated that a cup of Green Tea contains around 10-20mg of L-Theanine on average, which is less than the amount found in most supplements.

Matcha may contain more–since you’re drinking the actual green tea–but not by much.  A strong cup of matcha may have 30-50mg of Theanine, but that’s not enough for most people.

This means that if you want to the benefits of Theanine, you must supplement with it.

Why Do People Supplement With L-Theanine?

Why do people supplement with Theanine

As mentioned earlier, Theanine is usually supplemented as L-Theanine.

All amino acids have and L-form and a D-form.  There are a few exception (like DL-Citrulline Malate and D-Aspartic Acid), supplements usually contain the L-form.

This is definitely the case with Theanine, so if when choosing the right supplement for you, look for that “L” before the word Theanine.

Since Theanine has an extensive array of potential benefits, there are a lot of reasons why people use it.

Mostly though, it has to do with the relaxation, calming, and anti-anxiety properties which Theanine has been shown to possess.

Theanine has been shown to:

  • Reduce Anxiety
  • Promote Relaxation
  • Improve Cognitive Function

As well as several other unique benefits which we’ll get into shortly.

The main takeaway here is that supplemental L-Theanine is used by a ton of people for many reason.  There is no single reason why people use Theanine, as is the case with many other supplements.

What Are The Benefits Of Theanine?

Theanine Benefits

There’s no one reason to use Theanine.

Although it only recently appeared on the supplement scene, it’s been used (in the form of Green Tea) for literally thousands of years.

That said, modern science has only recently started to study Theanine in isolation and, in doing so, has uncovered a myriad of unique health benefits.

Let’s start from the top…

Theanine Reduces Stress And Anxiety

Theanine has been shown to reduce both mental and physical responses to stress as well as anticipatory anxiety.

It works by interacting with various neurotransmitters in the brain which control how the mind and body deal with stress and anxiety.

L-Theanine has been shown to benefit all kinds of stress and anxiety-related conditions, from high pressure education to PTSD.

Interestingly, it does this all without causing drowsiness, like so many anti-anxiety drugs and supplements tend to do.

How is this possible, you ask?

Theanine increases alpha-wave activity, a type of brain oscillation which has an inhibitory effect, but not to the extent that it causes you to become tired or drowsy.

This increase in alpha-wave activity also explains how Theanine favorably impacts cognitive function…

Theanine Improves Cognitive Function

Theanine has long been suspected of improving certain aspects of mental function, including:

Considering it increases alpha-wave function without causing drowsiness, it makes sense that it would support these types of processes.

In other words:

By having a slightly inhibitory impact on the brain, Theanine avoid distractions and focus on the task at hand, whatever that may be.

Naturally, this has made of interest to both healthy people looking for a slight edge and those with some sort of cognitive impairment.

Theanine Can Help Treat ADHD

Due to it’s ability to improve attention and reaction time, scientists have begun to explore how Theanine may play a role in treating certain attention-related disorders.

Although the bulk of the research is relatively new–and somewhat theoretical at this stage–Theanine has been investigated as a potential treatment for ADHD.

Research shows that it may very well improve some aspects of ADHD, but as a stand-alone treatment, it’s no miracle.

Theanine Promotes Nitric Oxide Production And Blood Flow

One of the lesser known physiological impacts of Theanine is that it actually increases Nitric Oxide production in Endothelial cells.

By doing so, it acts as a vasodilator.

In other words, it relaxes blood vessels and can potentially improve blood flow.

Theanine has been shown to decrease heart rate and blood pressure in instances of stress.

Even though this is generally attributed to the anti-stress effects of Theanine in the brain, it could also be partially attributed to vasodilation.

This is also good news for bodybuilders and athletes, as it means Theanine may have the potential to improve physical performance as some other Nitric Oxide-boosting supplements have been shown to do.

Theanine Enhances The Benefits Of Caffeine While Reducing The Downsides

Green Tea is natural source of both Caffeine and Theanine, but doesn’t seem to cause side effects such as:

  • jitters
  • anxiety
  • vasoconstriction

That many other sources of Caffeine (like straight Caffeine or Coffee) are known for.

In fact, Green Tea, despite containing a decent amount of Caffeine, is known to be more calming than stimulating.

Theanine has long been suspected to be the reason for this.

As a result of this speculation, several studies have investigated the impact of Caffeine and Theanine, both in combination and in isolation.

The combination of Theanine and Caffeine has been shown to improve cognitive function to a greater extent than either substance alone.

Not only has Theanine been shown to reduce vasoconstriction caused by Caffeine, but it can also potentially lower the likelihood of other unwanted side effects as well.

There’s so much research on the synergistic benefits of Theanine and Caffeine that it’s really a no-brainer.

If you like Caffeine, you’ll love Caffeine + Theanine.

Dosing is all over the map, but benefits have been found at doses ranging from 50-200mg of Theanine combined with varying amounts of Caffeine.

Theanine Dosing

Theanine Dosing

There is no precise clinical dose for L-Theanine, but studies showing benefits have used doses ranging from 50-200mg.

If you’re combining it with Caffeine, try using at least the same amount of Theanine as Caffeine.

In other words, if you’re taking 200mg of Caffeine, try combining it with 200mg of Theanine and go from there.

There really is no upper limit for Theanine.  It’s virtually impossible to over-dose, so feel free to experiment a little in order to find you’re ideal dose.

Kinds Of Theanine

When it comes to supplements, you’ll find Theanine labeled as “L-Theanine”.  There is such a thing as D-Theanine–as is the case with all amino acids–but in this case, the D-form of useless.

Suntheanine® is the registered trademark for L-Theanine produced by the company Taiyo via a patented method.

It is said to be 99% pure L-Theanine, but most off-brand forms of Theanine claim roughly the same thing.

Ultimately, L-Theanine isn’t that difficult to produce, so while it’s always nice to have a trusted brand name attached to a particular ingredient, off-brand forms of L-Theanine are okay too most of the time.

In fact, most studies on Theanine have not used Suntheanine®, meaning it’s entirely possible to get 99% (or so) pure L-Theanine without using whatever method the patent pertains to.

Due to all the competition, however, the price of Suntheanine® has slowly come down over the years to the the point that it’s only slightly more expensive than off-brand L-Theanine, so that’s personally what I like to use.

My Personal Opinion On Theanine

I love Theanine.  It’s one supplement that I can honestly say I’ve experimented on and off with for years and have noticed some real benefit.

In fact, I won’t drink Caffeine without it…

Caffeine makes me jittery, anxious, and irritable.

Combined with the right dose of Theanine?  Those downsides fade dramatically and I’m left in a mental state in which I can be both productive and relaxed.

I would genuinely recommend taking L-Theanine to anyone who uses Caffeine on a regular basis.

The Bottom Line On Theanine

Theanine is a useful supplement for a lot of reasons.  Mostly, it’s known for promoting a state of “alert relaxation” which makes it useful for:

  • improving cognitive function
  • managing stress
  • combating the negative effects of stimulants

But it also has other mechanisms by which it can improve your health, as discussed above.

I’m Matt Theis, founder of SuppWithThat, Momentum Nutrition, and Singular Sport. I created SWT to separate the science from the hype and publish accurate, research-based information on supplements. If you like what I have to say here, feel free to check out my supplements at and

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