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L-Theanine & Caffeine: The Perfect Nootropic Stack?

Caffeine and l-Theanine

In the quest to get the most bang for their nootropic buck, many people stack their supplements. One of the most popular nootropic stacks combines l-theanine with caffeine. In this article, we get to the bottom of the l-theanine, caffeine double whammy so you can decide if it’s the brain boosting super duo that many claim it to be.

The idea to stack l-theanine with caffeine comes from nature, where they are both found in green tea leaves. It’s the reason that people have been using green tea extract for thousands of years to provide clear focus and relaxation.

Drinking coffee will hype up your energy levels. It also gives a person the jitters, along with a subseuqent energy crash. However, when it is paired with the theanine found in green tea leaves, these negative side effects are neutralized.

The synergistic effects of combining l-theanine and caffeine amplify the effects of taking either compound individually. They will also nullify the following effects of caffeine . . .

  • Hyperactivity
  • Lack of focus
  • Jittery muscles
  • Energy crash

Research into the combination of caffeine and theanine shows that they will produce the following effects . . .

  • Enhanced visual and special awareness
  • Increased muscle dexterity
  • Faster reaction times
  • Longer attention span

So, what is about these two compounds that make them so special. Let’s now investigate them one by one. Then we’ll discover how their combination makes them even more effective.


Green Tea Powder

L-Theanine is an amino acid that is found mainly in green tea leaves. It is a non-essential amino acid. It is unique in that it has been shown to relax the mind without causing drowsiness.

L-Theanine is recognized as an anxiolytic nootropic in that is a reducer of anxiety. It will enhance the quality and quantity of sleep. It has also been shown to reduce the symptoms of stress and bring about a feeling of calmness, while also reducing the heart rate and blood pressure.

Other anxiolytics, such as valerian root and hops, have a sedative effect that depresses the central nervous system. L-Theanine does not do that. Instead, it actually increases the number of calming brain chemicals.

Another great benefit of l-theanine is that it has powerful antioxidative properties. Oxidative stress can be very damaging to the brain. Apart from neutralizing these effects, l-theanine has potential to offset some of the cognitive declines that come with age.


Stress Reducer

L-theanine is a stress and anxiety reducer. It also reduces the physical symptoms of stress while also boosting feelings of calmness. These benefits are largely responsible for the global popularity of drinking tea (it is the second most popular drink in the world, after water!).

Research has revealed that l-theanine very effectively reduces the levels of cortisol in the body. Cortisol is known as the stress hormone. Theanine also reduces both psychological and physiological stress responses. It leads to a feeling of ‘alert relaxation.’

Enhanced Memory, Mood & Attention

Researchers have identified that l-theanine has the ability to perform what they call sensorimotor gating. This process acts as a filter of environmental stimuli to prevent an overload of irrelevant information in the higher cortical centers of the brain. This leads to improved attention, focus and learning.

The ‘gating’ ability of l-theanine also reduces distraction, boosts alertness and improves a person’s ability to focus.

Better Sleep

Better Sleep

Theanine has the ability to improve a person’s ability to fall asleep and to get a better quality of sleep. It does this without causing daytime drowsiness or the negative side effects that come with other sleep boosters.

Blood Pressure

L-theanine has been shown to significantly lower the systolic and diastolic blood pressure. In one study, this effect was the most pronounced among people who had exhibited a high rise in blood pressure in response to psychological stress.

In contrast to l-theanine, caffeine is known to elevate blood pressure in response to stress. However, when taken in combination with l-theanine, caffeine does not increase blood pressure.

Improves Cancer Treatment

Research has uncovered some very encouraging potential regarding the use of theanine as an adjunct therapy for cancer. Human and animal trials have shown that theanine can suppress the growth of lung cancer and leukemia cells, boost the anti cancer activity of cancer treatments like trichostatin and reduce cancer cell migration and invasion. Further study suggests that l-theanine may be an effective chemopreventative agent for cancer.

How Does L-Theanine Work?

Neurotransmitters How

L-Theanine modulates certain brain chemicals, increasing the level of inhibitory Better Sleep. It also blocks the over production of excitatory neurotransmitters.

The chemical structure of l-theanine is similar to that of glutamate, which is the primary excitatory neurotransmitter. That gives l-theanine the ability to bind to and block glutamate receptors in the brain. This brings down the levels of glutamate, preventing glutamate receptor over activity which is triggered by stress. The result is a level of calmness and relaxation.

L-Theanine has also been shown to increase the levels of calming neurotransmitters, including dopamine, serotonin and GABA. All three of these neurotransmitters are key to the regulation of mood, alertness, energy and sleep.

This amino acid is also able to suppress overproduction of the stress hormone cortisol while also triggering the release of alpha waves. This level of brain activity that brings on a wakeful relaxation.

L-Theanine is a water-soluble amino acids. It is metabolized in the kidneys. It also easily crosses the blood-brain barrier. The blood brain barrier is a protective mechanism to protect the brain from blood borne toxins. It consists of a layer of specialized membranes and cells.

L-Theanine will reach its highest blood concentrations in less than an hour.


As we’ve already noted, L-Theanine works best when taken with caffeine. The most effective ratio has been shown to be 2:1 in favor of theanine. A typical does is 100-200mg theanine with 50-100 mg caffeine. However, those who are not able to tolerate caffeine very well are advised to stick with the lower level of 100:50 mg.

Side Effects

The US Food and Drug Administration has designated L-Theanine as a GRAS (Generally Recognized as Safe). As a result, it is considered to be a very safe nootropic ingredient. In tests with animals, extremely high doses over long periods did not produce any adverse side effects.

There have been some minor side effects noted with regard to l-theanine supplementation. These include . . .

  • Dizziness
  • Headaches

Both of these side effects are minimized when l-theanine is stacked with caffeine.


The Caffeine​ Molecule

Caffeine can be found in more than sixty plants. These include tea leaves, kola nuts and cocoa beans. There are also a number of synthetic versions of caffeine.

Caffeine is not technically a nootropic. The reason is that it is also a stimulant. However, it is well known to improve cognitive performance. It also improves alertness and provides an energy kick.

Caffeine has been used for thousands of years as an energy booster. It was extracted from the cocoa bean for the first time by Fredrich Ferdinand in the 1820’s. Now there are three key ways to extract caffeine. Though we normally associate caffeine with coffee, it is available in an amazing array of forms.

Caffeine may listed on the ingredient label in the following forms . . .

  • Coca
  • Camilla
  • Guaran berries
  • Yerba mate
  • Guarana
  • Kola nut
  • Guyausa

How Does It Work?

Caffeine is a replacement in the body for the chemical adenosine. The purpose of adenosine is to make sure that the nervous system doesn’t become over excited. Throughout the day our levels of adenosine naturally build up in the body. It acts as a brake on the central nervous system. In the evening the levels are at their highest, which slows you down and makes you sleepy. Adenosine plugs into receptor sites to do their job of blunting your central nervous system.

Caffeine mimics adenosine in reverse. It is such an effective impersonator of adenosine that it is also able to plug into adenosine receptor sites. If both adenosine and caffeine are competing for the same receptor site, caffeine will always beat out adenosine.

An effect of caffeine on receptor sites is that dopamine is released. Dopamine is a neurotransmitter which has been shown to activate the brain’s pleasure centers. Dopamine also boosts concentration and focus.

Blocking adenosine may reduce the buildup of amyloid-beta, which is a toxic brain plaque that has links to Alzheimer’s disease


Increased Alertness

Wide Awake Person

Increased alertness is the thing that most people think of when considering caffeine’s nootropic benefits. However, the energy boost that you get with caffeine does not last for very long. Immediately after you take caffeine into your body, more dopamine will be released. This hormone stimulates the parts of the brain that are responsible for alertness, problem solving and pleasure. This will give you an instant feeling of being sharper.

The amount of caffeine in a single cup of coffee (about 100mg) will give you a mental boost for about 45 minutes. In terms of drinking coffee, a recent Harvard study showed that men who drink 4 cups each day are half as likely to develop Parkinson’s disease as those who did not drink coffee.

Cardiovascular Health

Adenosine helps the blood vessels to relax. However, when coffee gets into the receptors that line the vessel walls, the arteries constrict. Research has shown that blood pressure may increase by as much as ten points in non-habitual drinkers of coffee. However, there is more to the story. Research conducted at Harvard University tracked the coffee consumption of 128,000 people. It was found that drinking more than six cups of coffee per day did not boost they chance of developing heart disease. Then a 2018 study out of Brooklyn College recorded that people who consumed four cups of caffeinated coffee daily had a 53 percent reduced risk of dying of heart disease compared with non-drinkers.

Improved Muscle Performance

Caffeine boosts the central nervous system to enhance your energy levels, if only temporarily. The effect of this will be that your heart rate will increase a little, along with your rate of breathing. These two things will assist you to perform better physically as they will bring more oxygen into your system.

Over and above this effect, caffeine may directly affect your muscle performance. A muscle fiber can only contract when calcium is released. It is believed that when caffeine blocks the adenosine receptors attached to your muscle fibers, the electrical impulses that are triggered release higher dosages of calcium. This results in a stronger muscle contraction.

Taking between 140 and 400 mg of caffeine as part of a pre-workout formula is believed to be able to speed up both speed and endurance.

Side Effects

Studies have shown that caffeine is safe for most people at low to moderate dosages. Genetic predisposition also determines a person’s tolerance level to caffeine. At high dosages most people will experience some serious side effects.

The first and most obvious side effect of caffeine is that it can lead to a sudden and noticeable energy crash. This will usually occur some 45 minutes after taking it. This time length appears not to change, regardless of the dosage taken. However, larger dosages [in excess of 400 mg] will produce a more heighted energy crash.

At high dosages, the adenosine blocking effects of caffeine may lead to anxiety. Symptoms includes extreme nervousness and jitteriness. One study that involved 25 men who took 300 mg of caffeine had double the recorded level of stress as compared to those who took a placebo.

Caffeine is well known for its ability to ward of sleep and help students get through an all-nighter. However, the flip side is that it may also lead to insomnia. Studies have shown that increased caffeine intake increases the length of time it takes to get to sleep as well as reducing the quality and quantity of your sleep.

It has also been shown that taking caffeine in the evening can make it harder to get to sleep. 300 mg taken with two hours of retiring may delay the ability to get to sleep by as much as 90 minutes. Consequently, it is recommended that you do not take caffeine into your system within five hours of going to bed.

The Power Of Synergy


In the section on caffeine, we’ve identified the pitfalls that come with taking caffeine into your system. The main ones are anxiety, restlessness and elevated blood pressure. The beauty of stacking creatine with l-theanine is that theanine has the ability cancel out these negative side effects.

Caffeine acts by inhibiting the activity of adenosine receptors in your brain. L-theanine dampens down excitatory responses that result when caffeine mimics adenosine and plugs into adenosine receptors.

So, when you take caffeine and l-theanine together, you get to enjoy all of the brain and energy boosting effects of caffeine without the anxiety, jitters or increased blood pressure that you would normally have to put up with.

Because caffeine is a vasoconstrictor, it makes the blood vessels smaller, which makes it harder to maintain blood flow and increases the blood pressure. However, l-theanine negates the vasoconstrictive properties of caffeine, so that your blood flow is normalized.

L-theanine appears to even help with the infamous caffeine crash  that most people experience forty-five minutes after putting caffeine into their system. Caffeine crashes can lead to headaches and fatigue. Yet, a 2008 study showed that people who stacked theanine with caffeine had fewer headaches and were less tiredness compared with those who took caffeine alone.

Combining caffeine with l-theanine can also help to overcome the night-time problems associated with taking caffeine later in the day. A lot of people have real problems at bedtime when they take caffeine after 3pm. This is a problem for guys who hit the gym in the evening and want to take caffeine as a part of their pre-workout formula. Taking it as a stack with l-theanine, though, will alleviate your caffeine sleep problems.

Caffeine affects our slow-wave sleep. This is the deepest form of non-REM sleep. You need to get a decent level of slow wave sleep for an adequate overall sleep experience. L-theanine blunts the central nervous system stimulating effects of caffeine to stop the anti-sleep side effects that it usually brings with it.

Not only does the addition of l-theanine negate the side effects of caffeine, but the two of them together boost the effects of using them beyond what you would get from using them individually.

When combined, l-theanine and caffeine will significantly increase reaction times over using them by themselves. One study showed that people who stacked the two supplements had an improved reaction time for delayed word recognition. Another study reported that subjects had a faster reaction time to flashing light cues on a computer when they stacked caffeine with l-theanine.

Stacking these two supplements has also been seen to improve people’s level of focus and concentration when switching between tasks. A 2008 study showed that there was a marked improvement in test accuracy for people who stacked the supps over those who either took one or the other.

Further research has shown the impressive ability of a caffeine, l-theanine stack to be able to reduce distractions when you are trying to focus on a task.

On The Downside

Downside Thinking

We’ve seen a lot of positives that result from pairing caffeine with l-theanine. In the interests of full disclosure, however, we need to also put some of the potential problems that have been identified with a caffeine, l-theanine stack.

Some studies have not shown increased alertness when the two supplements were taken together, though there was greater alertness when they were taken individually. Also, the stacked supplements did not deliver the expected focus and attention gaining benefits on prolonged tasks that require intense concentration.

Caffeine stacked with l-theanine also did not improve the mood of subjects tested in clinical trials.

Another potential problem with stacking caffeine with l-theanine may present itself for people who are prolonged and heavy consumers of caffeine. These people may have already develoed a tolerance to caffeine which has caused them to have a diminished sensitivity to the substance. When the central nervous system blunting effects of l-theanine are put on top of this it, it may not give enough of a caffeine effect to have any result.

Stack Dosage

A daily caffeine-l-theanine stack should always follow a 2:1 ratio in favor of theanine. You can safely take 100-200 mg l-theanine and up to 400 mg of caffeine, daily according to the FDA. The best results seem to come from a dosage of 200 mg of theanine stacked with 100 mg of caffeine.

Do not mix l-theanine with blood pressure medications. This could reduce your blood pressure excessively.

The Bottom Line

Caffeine and l-theanine are a smart combination of supplements to provide a nootropic effect that safely manages to overcome some of the problems that come with caffeine.

This combination will allow you to benefit from the energy boosting, focus, alertness and concentration enhancing benefits of caffeine without having to put up with central nervous system over-excitation, energy crash effects, vasodilation , increased blood pressure and insomnia.

The caffeine, l-theanine stack can also be useful for people who work out in the evening and wish to take a creatine based pre-workout supplement before hitting the weights. The addition of l-theanine will negate the insomnia inducing effects of caffeine so that you can still get a good night’s sleep.

Take your caffeine, l-theanine stack in a 2:1 ratio in favor of theanine. We suggest a daily dosage of 200 mg of l-theanine and 100 mg of caffeine.

Read our NooCube review to see how one of the leading nootropics available “stacks” up against l-theanine + caffeine.

Key Points

  • Caffeine / L-Theanine Are An Ideal Nootropic Stack
  • Theanine Will Blunt Many Of The Side Effects of Caffeine
  • Taking The Stack With The Evening Pre-Workout Will Help You Get a Better Night’s Sleep
  • Theanine Takes The Edge Off The CNS Boosting Effects Of Caffeine
  • Take Caffeine / L-Theanine In A 2:1 Ratio In Favor Of Theanine
  • Recommended Dosage – 200 mg Caffeine / 100 mg Theanine

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