L-theanine - An Overview
L-theanine (r-glutamylethylamide) is a unique type of amino acid that has been proven to:
It is prized for its ability to modulate brain waves and neurotransmitters in a way that promotes a relaxed but clear-headed state.
It is by far one of the most popular and widely used nootropic supplements out there, especially when paired with caffeine.
This nootropic compound also has several benefits for the body as well, including lower blood pressure,
This compound naturally occurs in the leaves of the species Camellia sinensis AKA the tea plant.
L-theanine and Caffeine
L-theanine is what gives brewed tea, particularly green tea, it’s calming effects.
Because tea contains this chemical, it is far less likely to cause the jitters than coffee (which does not have l-theanine).
You may have noticed that drinking tea is far less “speedy” than coffee, despite similar caffeine levels.
L-theanine acts as a counterweight to caffeine, calming the mind and body as the caffeine stimulates it.
This action has a synergistic effect, creating an energized focus free from the anxious energy associated with too much caffeine.
In fact, l-theanine plus caffeine is considered to be the simplest, but most effective, entry-level nootropic stack out there.
If green tea is not your thing, you can purchase l-theanine as a bulk supplement for cheap.
Many people take it before their morning coffee to balance out their morning caffeine rush and sustain their energy and mood.
What Does L-theanine Do?
L-theanine has numerous research-backed benefits for cognition and bodily function.
Does L-theanine Help with Anxiety?
One of the primary ways it works is by relieving stress in the brain and peripheral nervous system.
One human study found that supplementing l-theanine under stressful conditions reduced indicators of anxiety.
In this trial, young participants were told to complete a difficult math exam. Some were given l-theanine, others were given a placebo.
When researchers measured the subjects after the exam, they observed “reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition.”
In other words, the physical markers of stress were not as high in the group that took l-theanine.
This lead the team to conclude that “the oral intake of L-Theanine could cause anti-stress effects.”
1Kimura K, et al. L-Theanine reduces psychological and physiological stress responses, Biol Psychol. 2007
A similar study backs up the findings of the one described above.
These researched also reported “reduced Tension-Anxiety scores as compared with placebo intake” after subjects completed a mental performance test.
L-theanine’s anti-anxiety abilities is most likely a result of it’s ability to lower stress hormones, such as cortisol.2Yoto A, et al. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses, J Physiol Anthropol. 2012
Focus and Attention
L-theanine has a nootropic effect on focus and attention.
Multiple studies have suggested that l-theanine can modulate both the brainwaves AND the neurotransmitter chemicals that are closely associated with attention and staying on task.
Anecdotally, many users claim that l-theanine puts them “in the zone,” especially when combined with caffeine.
One study found that even in smaller amounts, such as what you might find in a single cup of green tea, l-theanine can increase alpha waves in the brain.
Alpha waves are associated with mental alertness and arousal.
The study only looked at smaller doses on l-theanine, but we can expect that larger amounts, such as those you might get from supplementing, would increase this effect.3Nobre A. L-theanine, a natural constituent in tea, and its effect on mental state, Asia Pacific Journal of Clinical Nutrition. 2008
Another interesting study looked at the combination of theanine and caffeine specifically.
It found that subjects who took this combo performed significantly better at a series of cognitive tests.
The tests they administered measured “word recognition, rapid visual information processing, critical flicker fusion threshold, attention switching, and mood.”
Across the board, the participants who took l-theanine and caffeine were faster and more accurate when completing the tasks than the placebo group.
This led researchers to conclude that “L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.”4Owen GN, et al. The combined effects of L-theanine and caffeine on cognitive performance and mood, Nutr Neurosci. 2008
That study also claimed that l-theanine has a positive effect on mood, which is another benefit that many people report after taking it.
L-theanine is known to increase both dopamine and serotonin in the brain, both of which regulate mood and positive feelings.
L-theanine for Sleep
L-theanine is associated with better sleep.
Japanese researchers found that people who took 200 mg of l-theanine in the morning slept better at night.
They measured this through a series of laboratory brain wave tests, as well as self-report data.
The group that took l-theanine reported that they slept deeper, recovered from exhaustion quicker, and were better rested on waking up.
This is most likely due to l-theanine’s ability to promote the type of brainwaves that are conducive to sleeping soundly.
This may prove to be l-theanine’s most powerful effect. We have always maintained that the most important factors for brain health and cognitive function are sleep, diet, and exercise.
Any nootropic effect you get from a supplement is only going to augment whatever baseline level you are at with three basic factors.
So, if l-theanine helps you sleep soundly at night, that is going to make a huge difference in how well your brain works when you’re awake.5Kobayashi K. Name of Study or Article Here, Nippon Nogeikagaku Kaishi. 1998
L-theanine for ADHD
Its effects on sleep may also make l-theanine useful for treating ADHD.
A double-blind, placebo-controlled study conducted in 2011 found that young boys who took this nootropic had “significantly higher sleep percentage and sleep efficiency scores” than those who did not.
This is a potentially significant finding for the treatment of ADHD.
Disturbed sleep and irregular sleeping patterns are common for those suffering from deficit disorders, and both problems seem to exacerbate one another.
Not getting enough quality sleep seems to make symptoms of this disorder worse, so improving sleep could lead to fewer attention problems during waking hours, and (potentially) less reliance on other medication.
This is still a new avenue of study, and so far it has only looked at male children, so there’s not enough information to draw definite conclusions.
But, we think there is a possibility that future research could prove that l-theanine is an effective supplement for treating ADHD.6Lyon MR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial, Altern Med Rev. 2011
L-theanine for Neuroprotection
L-theanine may also work as a neuroprotectant. It has anti-inflammatory properties that could reverse some of the downsides of aging.
It’s an unfortunate fact that as we get older, our brains stop functioning as well.
Important neurotransmitters don’t work like they used to, oxidative stress levels damage neurons, and long-term memory and cognition decline.
In short, the stresses of life gradually take their toll on your brain, and it gets harder and harder for to stay in top mental shape.
Luckily, taking l-theanine might reduce and even reverse these issues, ensuring that your brain keeps some of its youthful elasticity.
One study found that a combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment.
Participants suffering from age-related cognitive impairment were given either l-theanine or a placebo for 16 weeks.
Neuropsychological tests and measurements of brain electrical activity were conducted to evaluate the effect of l-theanine on memory and attention.
The group that had taken l-theanine showed remarkable improvement on these tests, as opposed to the control group, which did not.
The research team concluded that there is strong evidence that l-theanine “has potential as an intervention for cognitive improvement.”7Park SK, et al. A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study, J Med Food. 2011
There’s even evidence that this nootropic can prevent a stroke. One Chinese study found that people who regularly drank tea were 40% less likely to suffer from a stroke than those that didn’t.8Chen Z, et al. A study on the association between tea consumption and stroke, Zhonghua Liu Xing Bing Xue Za Zhi. 2004
Does L-theanine Help You Lose Weight?
It is possible that l-theanine could have some benefits when it comes to shedding fat.
In multiple animal studies, this compound reduced fat absorption, raised metabolism, and regulated glucose and triglyceride levels. All of these functions could have a noticeable effect on body composition. 9Quan V Vuong, et al. L-Theanine: properties, synthesis and isolation from tea, J Sci Food Agric. 2011 10C Juhel, et al. Green tea extract (AR25) inhibits lipolysis of triglycerides in gastric and duodenal medium in vitro, J Nutr Biochem. 2000 11Swen Wolfram, et al. Anti-obesity effects of green tea: From bedside to bench, Molecular Nutrition & Food Research. 2006
Although these results have yet to be replicated in human studies, it is a promising initial finding.
Additionally, l-theanine may have an indirect effect on weight loss by improving sleep. Getting proper rest is heavily linked to appetite, blood sugar levels, metabolism, and hormone regulation, all of which affect body composition.
How L-theanine Works In The Brain
L-theanine’s powerful nootropic effects come from a few different modes of action.
One interesting effect that l-theanine has on the brain is that it increases alpha brain waves and lowers beta waves in the brain.
Typically, nootropics work by modulating chemicals and neurotransmitters, not brain waves.
L-theanine is pretty unique in that it can directly alter the electrical output of your brain signals.
Alpha and beta waves are electrical signals produced in different mental states and are both important for focus, concentration, and general arousal.
However, there are some key differences between the two.
Beta waves are the fastest waves your brain produces, and are associated with focused, deliberate action.
Beta waves are important because they increase concentration and keep you engaged in your task, but they are also linked to higher levels of stress and anxiety.
Too many beta waves can overstimulate you and actually be counter-productive.
Alpha waves, on the other hand, are slower and higher in amplitude than beta waves. They indicate a more relaxed, less aroused state.
This is the type of brain activity you generally see in somebody meditating or taking a walk.
This is the type of brain wave that will help you get “in the zone.”
Several studies indicate that l-theanine increases alpha waves, which is one major reason that many users report a state of happy, relaxed focus.12Nobre AC, et al. L-theanine, a natural constituent in tea, and its effect on mental state, Asia Pac J Clin Nutr. 2008
L-theanine also affects cognition by boosting several of the neurotransmitters associated with mood and focus.
L-theanine easily crosses the blood-brain barrier, where it quickly starts raising the levels of GABA, serotonin, and dopamine.
These neurotransmitters are all involved in emotional regulation, motivation, positive outlook, and general feelings of well-being.13
Pradeep J. Nathan. The Neuropharmacology of L-Theanine(N-Ethyl-L-Glutamine), Journal of Herbal Pharmacotherapy. 2006
There is also evidence that l-theanine can reduce levels of cortisol, the primary stress hormone, as well as blood pressure, further promoting a feeling of calm.14Yoto A, et al. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses, J Physiol Anthropol. 2012
Just as important as raising the levels of these “positive” neurotransmitters, l-theanine is also effective in downregulating transmitters that can cause overstimulation.
L-theanine is an AMPA and NMDA receptor antagonist, which means that it prevents the release of glutamate.
Glutamate is an important excitatory transmitter in the brain that increases brain activity. However, too much glutamate can result in overstimulation and agitation, leading to poor mood and lack of focus.
Luckily, l-theanine has a very similar structure to glutamate, and binds to the glutamate receptors, blocking its reuptake.
So, by limiting glutamate levels in the brain to proper levels, this nootropic may help keep you calm and focused.
15Yamada T, et al. Effects of theanine, r-glutamylethylamide, on neurotransmitter release and its relationship with glutamic acid neurotransmission, Nutr Neurosci. 2005
Neuroplasticity and Protection
This action on NMDA/AMPA receptors also affects long-term potentiation and neuroplasticity, which is an important factor in maintaining brain health.
Neuroplasticity decreases as you age, making it harder and harder to learn and store memory.
L-theanine protects the brain as it ages by increasing your anti-inflammatory response.
L-theanine can also keep your brain fluid and healthy, promoting cognitive function as you get older.
When you are under stress, your brain starts working overtime, which has the unfortunate side effects of damaging your nerve cells with oxidation and free-radicals.
L-theanine can help your brain clean up these dangerous compounds before they start damaging your cells.16Sumathi T, et al. L-Theanine alleviates the neuropathological changes induced by PCB (Aroclor 1254) via inhibiting upregulation of inflammatory cytokines and oxidative stress in rat brain, Environ Toxicol Pharmacol. 2016
There is some preliminary evidence from animal studies that l-theanine can increase blood flow to the brain.
This is obviously a positive effect, but more studies will be needed to verify whether this holds true for humans as well.17Dodd FL, et al. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood, Psychopharmacology (Berl). 2015
L-theanine Potential Side Effects
Surprisingly, there have been no reports of l-theanine side effects or overdoses. This is probably about the safest nootropic supplement you can take, although you should still only take it at recommended doses.
We strive to bring you the most up to date, research-based information about L-theanine and other nootropics.
Something we missed? Do you use L-theanine? Share your thoughts and experiences in the comments below.
About the author:
Erik Levi is a co-founder of HolisticNootropics.com and a certified holistic nutritional therapy practitioner.
As an NTP Erik takes a nutrition first approach to health. He has worked with many different people to help them use nutrition to optimize their quality of life.
Erik believes that mental health is a physiological process and cognitive enhancement is not something that can be achieved by just taking some pills with good Amazon reviews.
Instead, true cognitive enhancement comes with the right balance of nutrients, movement, and gratitude. Erik continues to stay up to date with the most current nootropic and holistic health research and promises to deliver the best solutions possible.
You can check out his personal health blog/podcast/YouTube Channel all under the name Holistic A-Hole.