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L-Theanine (r-glutamylethylamide) is a non-dietary amino acid found in green tea (camellia sinensis), and the mushroom Xerocomus badius. Structurally, L-Theanine is similar to the neurotransmitters l-glutamate and l-glutamine.
L-Theanine easily crosses the blood-brain barrier. And taken as a supplement or by drinking green tea, reaches your brain within 30-45 minutes.
L-Theanine can lower blood pressure, rejuvenate and relax you, boost your ability to think, improve focus and change your mood. L-Theanine balances brain chemistry and improves cognitive health.
L-Theanine helps:
- Brain Waves. L-Theanine boosts alpha brain waves (8-12Hz) promoting alert relaxation.[i] And theta brain waves associated with creativity and relief from trauma.
- Neurotransmitters. L-Theanine increases GABA, serotonin and dopamine levels in your brain. Producing an energizing and calming effect. And improving cognition and memory.
- Neuroprotection. L-Theanine is an agonist of NMDA receptors and can inhibit synaptic release of glutamate. Protecting your brain from over-stimulation caused by glutamate, and possible glutamate toxicity.
Overview
L-Theanine (r-glutamylethylamide) is a non-dietary amino acid found in tea. And especially high levels in green tea (camellia sinensis). L-Theanine was first isolated from green tea in Japan by Sakato in 1949.
As an analogue of glutamate and glutamine, it’s hydrolyzed in your intestine and liver into l-glutamate and ethylamine. And easily crosses your blood-brain barrier.
L-Theanine is one of the very few nootropics known to modulate brain waves. It affects alpha brain waves which are associated with relaxation. Providing an alert calmness, L-Theanine helps in promoting super-learning, flow states and joy.
L-Theanine boosts the neurotransmitters serotonin, dopamine and GABA in your brain. As well as increasing Brain-Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF).[ii]
L-Theanine is known for helping to relieve stress, improve cognition, boost mood and cognitive function.
How does L-Theanine work in the Brain?
L-Theanine boosts brain health and function in several ways. But two in particular stand out.
- L-Theanine reduces physical and mental stress. L- Theanine helps increase alpha brain waves which are associated with mental relaxation and concentration.
One study in South Korea worked with 20 healthy male volunteers aged 18 – 30 years. One group was given L-Theanine tablets, and the other group a placebo daily for 7 days.
Brain waves were measured 40 minutes after administration of the tablets. The researchers analyzed alpha wave power values. And concluded that L-Theanine tablets promoted the release of alpha brain waves related to mental relaxation and concentration.[iii]
In May 2016, researchers at Simon Fraser University in Canada developed a technology to clinically measure brain wave patterns. With this technology, we’re now able to detect cognitive dysfunction before it happens. Imagine the implications of this new technology when applied to the nootropics world.[iv]
- L-Theanine increases neurotransmitters. Research shows that L-Theanine increases dopamine, serotonin, and GABA in your brain.[v] And it reduces the excitatory neurotransmitter glutamate which is associated with stress, tension and agitation.[vi]
A study done in Japan worked with 12 people who underwent 4 separate trials. One in which they took L-Theanine at the start of the experiment. One in which they took it half-way through. And two control trials in which they took either a placebo or nothing.
The results showed that L-Theanine resulted in a reduction in heart rate and s-IgA associated with acute stress. The researchers concluded that L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.[vii]
How things go bad:
As we get older, our brain chemistry and energy metabolism changes.
↓ Neurotransmitter levels decline
↑ Glutamate levels increase
↑ Stress levels increase
↓ Long-term memory and mood decline
↓ Quality of sleep declines
All of these changes can happen at any age once we reach adulthood. And are contributing factors to the neurodegenerative diseases of aging, and quality of life.
L-Theanine benefits
L-Theanine energizes without draining, calms without putting you to sleep, and motivates without causing a jagged edge.
Tea (as a source of L-Theanine) can have as much caffeine as some coffees. And yet doesn’t exert the same “speedy” effect. And the reason is the ingredient L-Theanine.
You can actually see L-Theanine’s effect in your brain using an EEG. Brain waves are smoothed out rather than flattened out.[viii] So your body is relaxed, your mind is calmed, but you don’t get sleepy. And L-Theanine, once it crosses the blood-brain barrier, raises levels of serotonin and dopamine.[ix]
L-Theanine even improves your quality of sleep. Researchers in Japan gave volunteers 200 mg of L-Theanine daily and recorded their sleep patterns. Sleep quality, recovery from exhaustion, and feeling refreshed were all enhanced by L-Theanine.[x]
And L-Theanine puts you in a better mood. Once it crosses your blood-brain barrier, L-Theanine changes levels of amino acids affecting serotonin, dopamine, and GABA. Having a modulating effect on mood.[xi]
How does L-Theanine feel?
Your unique neurochemistry including neurotransmitters, brain waves, brain structure and even regional brain activity will influence your response to L-Theanine.
Most neurohackers report a calming effect within 30 – 45 minutes of taking L-Theanine. Cognition gets a boost, and energy levels rise without the jitteriness caused by stimulants like caffeine.
Some report L-Theanine has stopped their anxiety and panic attacks. Just don’t combine it with anti-anxiety meds like Xanax.
Most report an overall improvement in the sense of well-being and quality of life. And nearly all remark on better quality sleep.
L-Theanine Clinical Research
Green Tea reduces incidence of stroke
Research has found that if L-Theanine is present in the body at the time stroke occurs, brain damage will be significantly reduced.
In this monster study done in China, researchers selected 14,212 subjects from 12 provinces. Ages ranged from 35 – 60 years old. The study looked at tea drinking status, dose and type of teas.
This study concluded there was a 40% decreased risk of stroke in those who drank green, black or jasmine teas.[xii]
L-Theanine improves memory
In this double-blind, placebo-controlled study, the effect of L-Theanine on memory and attention was investigated.
91 subjects with mild cognitive impairment were enrolled in this study. One group received 1,680 mg of L-Theanine daily for 16 weeks. And the control group received a placebo.
The study concluded that L-Theanine increased brain Theta waves associated with cognitive alertness and creativity. And there were improvements in memory. The results of this study suggested that L-Theanine has potential as an intervention for cognitive improvement.[xiii]
And that is an understatement by any stretch. People spend years meditating. With the goal of reaching consistent access to brain wave states like Theta. In this trial, they did it with a dose of L-Theanine. The same type of dose you could get with a few cups of quality green tea.
L-Theanine reduces stress
Considerable research has been dedicated to L-Theanine and its benefits to stress reduction in both animal and human studies. And we have ample documentation that corticosterone and stress exert negative effects on memory.[xiv]
Corticosteroids which are secreted after stress, have a profound impact on long-term potentiation and memory formation.[xv]
In this animal study, rats were fed water containing L-Theanine for 3 weeks and put through some stress inducing exercise. The researchers found that corticosterone levels were lower in the rats who used L-Theanine compared to those who had none.
In fact, stress had no effect on the animals who were fed L-Theanine. Memory was not affected. The researchers concluded that L-Theanine modified corticosterone secretion. And L-Theanine is a strong preventive measure in preventing memory loss otherwise induced by stress.[xvi]
L-Theanine Recommended Dosage
Recommended dosage of L-Theanine is 100 – 400 mg once or twice per day. With a maximum of 1,200 mg per day according to the Cleveland Clinic.[xvii]
L-Theanine is water soluble so you can take it with water.
Labels on quality green tea often only display the amount of green tea leaf available in each bag in milligrams (mg). But not its L-Theanine content. Green tea that’s steeped correctly will offer 1-2% L-Theanine per cup. So 1,500 mg of green tea leaf would be about 30 mg. of L-Theanine (at 2%).
We often say that YMMV, and this is especially applicable to L-Theanine. Find out what works best for you. Start at a lower dose like 100 mg. And work your way up until you achieve the effects you’re looking for.
L-Theanine Side Effects
L-Theanine is a naturally occurring amino acid found in plants like tea or one species of mushroom. So it’s considered non-toxic and very safe.
Theanine seems to decrease blood pressure. So if you’re on meds for high blood pressure, use L-Theanine with caution. Your blood pressure could go too low.
Type of L-Theanine to Buy
L-Theanine is available in green, black and white teas. Green tea contains the most L-Theanine.
A great side benefit for neurohackers is green tea also contains caffeine. A cup of good quality green tea has less caffeine than a cup of coffee. About 10 mg less.
L-Theanine + Caffeine stack
One study done at Unilever in the UK looked at the combined effects of L-Theanine and caffeine on cognitive performance and mood. They compared 50 mg of caffeine with and without 100 mg of L-Theanine.
The research team had 27 volunteers participate. And based measurements on word recognition, rapid visual information processing, critical flicker fusion threshold, attentions switching and mood.
Performance was measured at the beginning, and again 60 minutes and 90 minutes after consumption. Separated by a 7-day washout period.
Caffeine improved alertness at 60 mins. And accuracy on attention-switching at 90 mins. The L-Theanine and caffeine combination improved both speed and accuracy, and reduced susceptibility to distracting information on the memory task.
The research team concluded that, “L-Theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks”.[xviii]
And for an added bonus, L-Theanine takes the jittery-edge off of caffeine consumption.
The best pre-formulated caffeine + L-Theanine stack I’ve tried, and use is the new Performance Lab® Caffeine 2. It contains Natural Caffeine (from Coffea Robusta seeds) 50 mg, L-Theanine 100 mg, L-Tyrosine 250 mg, with a balanced NutriGenesis® B-Complex. For alert clean energy without the jitters.
L-Theanine from green tea
Extracting the optimal amount of L-Theanine from green tea is both art and science.
Researchers at the University of Newcastle in Australia set out to determine optimal conditions for water extraction of L-Theanine from green tea. They examined 4 different extraction methods. And learned that temperature, extraction time, ratio of water-to-tea and tea particle size had significant impacts on extraction yield of L-Theanine from green tea.
They concluded, “The optimal conditions for extracting theanine from green tea using water were found to be extraction at 80 °C for 30 min with a water-to-tea ratio of 20:1 mL/g and a tea particle size of 0.5-1 mm.” [xix]
So to get the most nootropic value when using green tea as your L-Theanine source – follow the directions. Just sayin’…
L-Theanine Supplements
L-Theanine is available in capsule or tablet form from several supplement manufacturers. Japanese company Taiyo is the oldest and most established company in the green tea supplement industry. Taiyo developed and patented a method for L-Theanine extraction from green tea called ‘Suntheanine®’.
Suntheanine can be found in some of higher quality pre-formulated nootropic stacks. For example, Mind Lab Pro® contains 11 brain enhancing nootropic compounds including Suntheanine.
Research has shown that some supplement makers using their own extraction method for L-Theanine, contain more than just the “L” form of Theanine. Turns out if it’s not done exactly right, you end up with a “D” form of Theanine.
D-Theanine may have a very different action in your body than L-Theanine. We’re not saying it’s dangerous. You just may not get all the benefit of pure L-Theanine.
So read the labels and reviews by people who have tried the product.
I recommend Mind Lab Pro because it uses Suntheanine. And addresses all aspects of anxiety resistance, memory and cognitive enhancement, stabilizes mood, brain repair, and maintenance.
This premium nootropic stack is designed to affect neurotransmitters, cognitive energy, brain waves, neuroprotection, and regeneration. See my Mind Lab Pro review for a detailed report.
You will also find Suntheanine® in the new Performance Lab® Caffeine 2. It contains Natural Caffeine (from Coffea Robusta seeds) 50 mg, L-Theanine 100 mg, L-Tyrosine 250 mg, with a balanced NutriGenesis® B-Complex.
Nootropics Expert Recommendation
L-Theanine 100 – 500 mg per day
I recommend using L-Theanine as a nootropic supplement.
Your body cannot make L-Theanine on its own. It’s a non-dietary amino acid only available from tea (and one little-known mushroom).
L-Theanine affects Alpha and Theta brain waves. This alone will help calm your mind, reduce stress, and help you stay alert. You’ll get even more cognitive benefit by stacking L-Theanine with caffeine.
L-Theanine helps boosts the neurotransmitters dopamine, serotonin, and GABA. Improving alertness and attention. And boosting cognition and memory.
And it reduces the excitatory neurotransmitter glutamate which is associated with stress, tension and agitation.
L-Theanine helps to prevent strokes, and even reduces the damaging effects if you’ve had a stroke.
And L-Theanine has been shown to improve sleep quality.
I suggest starting with a dose of 100 – 250 mg of L-Theanine daily for nootropic use. Using either a quality supplement, or high quality green tea.
Mind Lab Pro contains a synergistic blend of 11 brain enhancing nootropics covering all aspects of cognition and brain health. See my full Mind Lab Pro review for more.
Or for a smooth energy boost I recommend the new Performance Lab® Caffeine 2. For alert clean energy without the jitters.
Join The Discussion - 328 comments
aminos
October 19, 2021
Which is better for anxiety, GABA or L-theanine?
David Tomen
October 19, 2021
Aminos, it depends on what is causing your anxiety. If it is high cortisol or low dopamine or serotonin then L-Theanine may help. But if it is low GABA then a GABA supplement is your best option.
ALPHA
October 19, 2021
Does L-theanine have the same role as a benzodiazepine in the brain?
David Tomen
October 19, 2021
L-Theanine does not have he same role as benzos. Benzodiazepines attach to the GABAa (benzo) receptor to provide its anxiolytic action. You can read the article above to see how L-Theanine provides its anti-anxiety benefits.
Andy
October 18, 2021
Can I take 2 of these for sleep as its only 150MG
and how long before bed?
What would happen if I Took 600Mg can it be toxic?
Also How long does it last, Thank you
Doctor’s Best L-Theanine (Suntheanine) 150 mg
David Tomen
October 18, 2021
Andy, yes, you can take two capsules of this Suntheanine supplement about 60 minutes before bed. 4 capsules (600 mg) is not toxic but may backfire on you. More is never better with nootropics.
The half=-life of L-Theanine is about one hour. So once you take it it’ll be gone from your system in less than 2 – 3 hours. It’s enough time to calm you and help you fall asleep.
Kainyn
October 13, 2021
Hi, David.
I have untreated ADHD. I am new to nootropics so I have a few questions I was hoping you could answer.
7AM
L-theanine 100mg
Cup of coffee
Alpha GPC 600mg
1PM
L-theanine 100mg
Alpha GPC 600mg
(omit the coffee)
Would this stack have any issues? I would hate to cause damage to myself. I was considering 5-HTP, but cancelled my order of it when I watched your video on it.
Also, my husband and I will be starting a family in the next couple of years. What are the dangers of taking nootropics while pregnant?
Any advice you have to give is appreciated and taken very seriously.
Thank you for creating such a great community.
David Tomen
October 13, 2021
Kainyn, you’ll need to check with your doctor whether using these natural supplements are safe while pregnant. But I usually included that in my individual reviews in the “side effects” section of each article. Keep in mind that I am not a doctor and haven’t even played one on TV. I’ve figured this stuff out to save my own life.
There is nothing unsafe about the supplements you are considering. But they will not be enough to take care of ADHD symptoms. Please see my article on nootropics for ADHD here for recommendations: https://nootropicsexpert.com/best-nootropics-for-adhd-add/
Jesse
October 12, 2021
I Take this every night before bed 150MG from Dr.Best, sadly it has silicon dioxide in it however I also want to know it’s fine and safe too and cheery tart Cheertpure 500mg at the same time as my l-theanine however this also has silica. it’s almost impossible to find stuff without it?
I’m taking this brand of cheery tart
Life Extension – Tart Cherry with CherryPURE®
I hope this is correct for sleep
anyways
David Tomen
October 12, 2021
Jesse, silica is silicon dioxide and is found in quartz. It is used as a flow agent and anti-caking agent in encapsulation machinery. While there is no evidence that eating quartz or sand will cause anything other than indigestion, I personally do my best to avoid supplements that contain it. And instead use products like Mind Lab Pro and all the Performance Lab supplements.
But sometimes if we need a supplement and a ‘pure’ one is not available we don’t have any choice. Fortunately, silica is not directly toxic and does not cause inflammation or kill our immune system like some “other ingredients’ do.
Jesse
October 13, 2021
I’m more concerned if I had the correct Cherrytart from life extension and could mix L-theanine
Life Extension – Tart Cherry with CherryPURE®
I would get performance lab but it’s way out of my price range sadly
David Tomen
October 13, 2021
Jessie, CherryPURE® is a patented form of Montmorency Tart Cherry just like is used in Performance Lab® Sleep. And yes you can mix it with L-Theanine. But I think that by the time you add up the Life Extension tart cherry with a L-Theanine supplement you’ll be coming close to what you’d pay for Performance Lab® Sleep.
Paul
September 23, 2021
Hi David,
I’ve been using Suntheanine for a few weeks and i’m enjoying the effects if I don’t take too much and get foggy.
I also started agmatine recently to use synergistically with cannabis and other supplements as it potentiates them and reduces tolerance to many drugs. Then I realised it was an NMDA antagonist, and L-Theanine is an NMDA agonist. This has been confusing as I haven’t been able to find information on whether they just cancel each other out, or cause any damage from too much signalling on the receptors, and because both have so many benefits im not sure if I need an agonist or antagonist.
I’m focused on healing my general/social anxiety, mood, inflammation created by a histamine intolerance (DAO deficiency), possibly caused/fuelled by the chronic fungal infections since childhood (childhood stress). It took me about 2 years to figure out all of the issues and how they might be connected and a lot of research into treatments for each. Im 26 and already the stress and inflammation has resulted in damage including ADHD-like symptoms, anxiety, avoidant personality, depression, sleep issues, irritability/anger, poor at constructing sentences, memory, retaining information. They all seem to fuel each other.
I also take a B-Complex, zeolite powder, cycle Quercetin/Milk Thistle, NAC, Curcumin, Feverfew (migraines), cycle Resveratrol/Q10/ALA, Alpha GPC/Serine, Astragalus, Inositol, Omega 3, berberine (candida, blood sugar, antibiotic), cycle Ginkgo/Huperzine A. I also just added Mag Threonate, and GABA (liposomal). But it is quite confusing where the interactions may lie and if they can be avoided by taking them different times.
Do you have any recommendations regarding this, and the NMDA antagonist vs agonist possible clash? For reference I took the Braverman test and showed major deficit in GABA, Serotonin (both affected by histamine), then acetylcholine and a moderate deficit in Dopamine.
David Tomen
September 24, 2021
Paul, as far as I can tell agmatine attaches to those receptors but does not act as an antagonist or agonist. So there is nothing to worry about when using it with L-Theanine.
And you are correct that if used during the day, L-Theanine dosage should be kept to 100 mg per dose or it can make you sleepy. 200 – 400 mg works great as a sleep supplement.
You are fortunate that have been able to recognize what is going on and are learning to manage your symptoms while still young.
But why are you cycling some of these supplements? I suggest you revisit this and only cycle Huperzine-A which has a 24 hr. half-life.
I also suggest that you experiment with precursors to increase each neurotransmitter and see which ones work best for your symptoms. This article explains how to do this: https://nootropicsexpert.com/best-nootropics-for-anxiety/. For example, try 500 mg L-Tyrosine to increase dopamine and see how you feel. Then try 300 mg Alpha GPC to increase acetylcholine and see how you feel, etc.
Once you have an understanding on which neurotransmitters are dysfunctional you’ll have a better idea where to concentrate your efforts in building a stack that works for you.
And please see dosage recommendations here on Nootropics Expert for each nootropic you are using. For example, instead of cycling NAC you should be using 500 mg NAC 3-times per day. Same goes for several other supplements you are using.
David
September 13, 2021
Since L-theanine boosts serotonin, is this supplement safe to take along with L-tryptophan?
David Tomen
September 13, 2021
David, L-Theanine acts more like a serotonin reuptake inhibitor but nothing like prescription SSRIs. I use L-Theanine and L-Tryptophan every night before bed without a problem.
Mary O'Toole
October 12, 2021
Hi David,
Can i please ask how much dose of Theanine and Tryptophan do use to help you sleep.
Regards
Mary
David Tomen
October 12, 2021
Mary, it depends on your system and how much it needs. I personally use 400 mg L-Theanine and 500 mg L-Tryptophan.
Alex
July 24, 2022
Dear David,
They don’t interact with each other for absorption? You mentioned many times that Tryptophan fights with other amino acids to cross the blood-brain barrier. So it’s not a problem taking it same time with tryptophane?
David Tomen
July 24, 2022
Alex, the dosage is high enough that it should not be a problem.
Antoine
September 12, 2021
Hello David, Thank you for the generosity of sharing your knowledge, Do you think this is a good brand for Milk Thistle to avoid DNA damage by using Berberine? (I can’t get Zazzee USDA Organic Milk Thistle Extract in my country)
Bulk Supplements Milk Thistle Extract Powder for dogs
David Tomen
September 13, 2021
Antoine, Bulk Supplements is a trustworthy supplier so this Milk Thistle extract powder is likely high quality. But they say it’s for dogs. So I suggest checking with them before you buy it. Unless of course it’s for your dog.