November 22, 2022 7 min read

Coffee or tea? It’s an age old question, but you no longer need to choose. What if you could take the best qualities of both coffee and tea and use them to “biohack” your brain–that is, level up your cognitive performance? How do you do it? By matching up L-theanine and caffeine to create the perfect nootropic stack.

According to modern research, caffeine and L-theanine don’t just boost each other’s benefits, but they even each others odds. In fact, L-theanine, an amino acid prominently found in tea leaves, may be the answer to coffee’s jittery, anxious downsides. So, you may still have to make a choice on which hot cup you want to sip on, but pairing these two nootropic compounds is a no-brainer.

Here’s what you need to know:

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Table of Contents
Caffeine, Cognition, and Energy
What is L-theanine?
L-theanine and Caffeine
How to Use L-Theanine and Caffeine
Conclusion: What happens when you take L-theanine with caffeine?

Key Takeaways

  • Both caffeine and L-theanine have some brain-boosting benefits on their own, but they have significant synergy when paired together.
  • L-theanine could help to counter some of the side effects of caffeine,
A cup of hot nootropic coffee containing caffeine and l-theanine

Caffeine, Cognition, and Energy

Coffee, tea, energy drinks–they all have a few things in common. First, they all contain moderate to significant doses of caffeine. Second, the majority of American adults use one of these pick-me-ups almost everyday. In fact, 93% of people reported consuming caffeine regularly, 75% of which reported that they consumed caffeine at least once daily and 25% of which reported that they consumed caffeine three times daily or more.

While these seem like shocking numbers, it’s not that surprising. Life is busy and caffeine is the most readily available and affordable (legal) stimulant there is. But it’s not all that bad–caffeine is a naturally occurring compound that has some purported benefits, even when used consistently, like potentially boosting memory, increasing endurance during physical activities, and possibly even helping to prevent some types of cancer.

The Downside of Caffeine

Caffeine can give you the boost you’re after in as little as twenty minutes, but these stimulating effects can definitely have their downsides. In order to act as a stimulant, caffeine makes some changes in the brain. Mainly, it inhibits adenosine, a neurochemical that’s produced naturally as the brain functions throughout the day.

As adenosine builds up in the brain throughout the day, it begins to make you feel tired. Adenosine is necessary, though–it’s the primary reason that your body gets the urge to sleep after you run out of fuel (carbs and calories). Low adenosine production has been linked to low immunity. Plus, overconsumption of caffeine can increase your blood pressure and may worsen anxiety. Consuming a lot of caffeine can also cause you to need to urinate frequently, which is not only inconvenient, but can sometimes result in dehydration.

So, what if you could get the same benefits of caffeine (and possibly even more benefit) while consuming less caffeine and reducing the risks? Seems like a no brainer, right? That’s where L-theanine comes in.

A spoonful of L-theanine capsules near the tea leaves they are naturally sourced from.

What is L-Theanine?

L-theanine is one of the primary amino acids found in tea leaves at a concentration somewhere between 0.9-3.1% of the dry weight of the leaves, which translates to about 25-60mg in a 6 ounce serving of tea (made with approximately 2.5g of dried tea leaves). Aside from adding to the savory, bold flavor of most teas, it’s thought to have a few therapeutic benefits, acting both as a nootropic (cognition enhancing) and adaptogenic (stress regulating) compound.

Theanine is related to glutamine, the most abundant amino acid in the body, which is speculated to have a heavy impact on GABA, serotonin, and dopamine–the top three neurotransmitters required for most cognitive and nerve functions. In a healthy generalized scenario, the body can produce enough glutamine on it’s own, but factors like stress, injury, and exhaustion can cause the body to require more glutamine than it can make.

Luckily, L-theanine is believed to help boost the function of these neurotransmitters, so it may be a useful tool for aiding the body through the stressors of everyday life. What’s better is that L-theanine has been shown to be incredibly safe. In fact, no toxicity levels have ever been reported, and there is no evidence to suggest that it can cause and tolerance-building or dependency, so it’s a perfect option for daily dosing, especially if you can pair it with your morning coffee or tea to help decrease your dependency on caffeine.

Before we get ahead of ourselves, though, let’s look at how L-theanine may perform on its own:

L-Theanine Benefits and Research

Although most human trial sample sizes have been small, L-theanine’s effects on both cognition and stress have been heavily researched. A small 2011 study, for instance, found that L-theanine had a pronounced effect on attention and reaction time response in healthy adults who are prone to anxiety.

In a 2019 randomized controlled trial involving 30 healthy adults, researchers found that daily L-theanine supplementation decreased stress-related symptoms (involving depression, anxiety, and sleep) and increased cognition scores (involving verbal fluency and executive function). Ultimately, the authors concluded that L-theanine was safe and well-tolerated and may be a “suitable nutraceutical ingredient for improving mental conditions in a healthy population.”

One study involving 91 people found that a combination supplement of green tea extract (360mg) and theanine (60mg) helped to improve selective attention in subjects with mild cognitive impairments (such as ADHD).

There is much more evidence out there concerning the use and benefits of L-theanine–but biohacking your brain and body means leveling up this nootropic dose:

L-Theanine and Caffeine – The Perfect Pairing

So, how do L-theanine and caffeine stack up? The answer is–they don’t just stack, they synergize. In other words, when you take L-theanine and caffeine together, you don’t just get a mix up of their individual effects. The two even each others odds. They dance in harmony inside your body and brain to create a balanced effect you can’t get from either compound alone.

To understand this, let’s look at caffeine’s primary drawbacks–increased blood pressure, anxiety, and jitteriness. Research shows that L-theanine, when paired with caffeine, may reduce these effects.

One study, for instance, found that taking L-theanine with caffeine reduces caffeine’s impact on your blood pressure or anxiety levels. Why? Because it helps to prevent caffeine from dilating the blood vessels, allowing it to do it’s normal brain-boosting shenanigans without the negative impact on your blood flow.

Another study found that L-theanine may help to regulate your sleep schedule despite caffeine's tendency to keep you awake. Plus, this study also suggests that L-theanine helps to protect your low-wave sleep cycles against caffeine’s impact. Low wave sleep is the deepest cycle of sleep and it has a major impact on sleep quality and restfulness. So, L-theanine may help you sleep better at night and feel more rested the next day, decreasing your overall need for caffeine.

According to other research, caffeine and L-theanine have some serious synergy–like improved reaction times, improved word recognition, and improved attention. Another study shows that the two nootropics paired up to help people switch between tasks more easily, and another found that subjects completed tasks with more accuracy after taking a combination of the two.

A person holding a single L-theanine capsules taken alongside other morning supplements.

Are there any drawbacks to combining caffeine and L-theanine?

There are some imperfections between this paring, of course, but they aren’t exactly drawbacks. For instance, one study found that although the pair did increase task-switching capabilities, they had no significant impact on alertness. Another study also found the pair to have no impact on overall mood. Still, in almost every case where L-theanine and caffeine failed to improve each other’s effects, they didn’t exactly cause any degraded cognitive or physical effects either.

How to Use Caffeine and L-Theanine Together

There are many ways to pair these two brain-boosting supplements to create the perfect nootropic stack. You can simply buy the two separately and take them together. For instance, you could take an L-theanine capsule about 30 minutes before consuming caffeine, and then take your caffeine however you like it.

L-Theanine and Caffeine Dosage

L-theanine and caffeine dosage is pretty subjective–everyone has their own tolerance to caffeine. You’ll likely need to do a little trial an error to figure out the best dosage for you, but trial and error is at the core of this kind of biohacking. After all, you are a unique individual, so you may need 50 milligrams of caffeine or you may need 100.

In general, though, the perfect ratio of caffeine to L-theanine is 1:2, or 100 milligrams of caffeine to 200 milligrams of L-theanine. You don’t have to get this exact–just close enough to experience the full synergy of the two within your own dosing threshold. And remember–you may even find that you need less caffeine than usual because it’s effects are being boosted. This is especially true over time–as sleep quality and other lifestyle factors are enhances, you may find that your need for caffeine is less and less.

When to take L-theanine and caffeine?

It may seem obvious, but the best time to take this nootropic duo is right at the start of your day. The effects are pretty instantaneous, and the stimulating effects do eventually wear off (thank goodness, or you wouldn’t sleep), so it’s best to have this nootropic stack in the fashion of an early morning cup of joe or something similar.

How long will the effects of L-theanine and caffeine last?

Caffeine affects everyone differently, and you may find that the general effects of caffeine last about the same amount of time for you whether taking it with or without L-theanine. One study suggests that the combo can boost cognitive performance for up to six hours, though it may be more or less depending on your personal lifestyle factors, tolerance, and other unique factors.

Conclusion: What happens when you take L-theanine with caffeine?

L-theanine works on it’s own to offer nootropic and general wellness benefits, but when you pair it with caffeine, the two enhance each other’s effects. If the research rings true, taking L-theanine with caffeine will help you experience increased focus and energy levels, improved endurance, better sleep quality, and lower stress levels. , awareness, and energy, as well as reduced stress and improved mental endurance to even higher levels.


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