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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 - 317 comments
Andrew
October 18, 2022
I have this brand of L-theanine
Sports Research L-Theanine 200 mg
However it does relax me but it does not really put me to sleep it’s at 200MG in fact when I first got it and started taking it, it worked rather well Have I become tolerant of it should I increase to 400MG? I did take a break from it for a little while and still feel like I ahve build up some sort of tolerance toward it
I found when I took normal L-theanine at 100 that is not sun-theanine it made me very tired should I swap why is there a difference here?
David Tomen
October 22, 2022
Andrew, I prefer the patented forms of these supplements when available because chances are much higher that what is says on the label is actually present in the capsule. The manufacturer pays a premium for licensing the branded ingredient.
But go back up and get a good grasp of how L-Theanine works. It does not physically increase these neurotransmitters. It works with what is already present in your brain. You can potentiate the way it works by pairing it with L-Tyrosine.
James
January 9, 2023
Hey David,
When you say here that pairing L-Theanine with L-Tyrosine will potentiate the way it works, do you mean in a similar way to how caffeine and L-Theanine go together?
Or does Tyrosine and Theanine synergise differently than how caffeine and L-Theanine does and if so, how does it differ?
Thanks 🙂
David Tomen
January 10, 2023
James, they work differently. Caffeine forces your brain to use more dopamine. L-Theanine helps your brain use dopamine more efficiently. Using L-Tyrosine to raise dopamine means L-Theanine helps that Tyrosine work more effectively.
Morgan
October 10, 2022
Since L-theanine increase dopamine and serotonin, can it be effective as a “anti-depressant” ?
David Tomen
October 10, 2022
Morgan, it can be used as an antidepressant successfully in some people.
Pablo Jimenez
September 16, 2022
Hello David,
I’m having trouble sleeping. I started taking 200mg L-Theanine together with 500mg Magnesium and 500mg of Gaba. I wake up a few times at night and can’t go back to sleep. I’m also taking 200mg L-theanine in the morning for my anxiety and so far is working.
What do you recommend, should I lower the dosage or remove any of those supplements that I take at night or should I add any other supplements to that stack?
Thank you
David Tomen
September 17, 2022
Pablo, try adding 500 mg L-Tryptophan and if that is not enough then 20 – 40 mg CBD Oil. I use the “calm” gummies from Charlotte’s Web (https://bit.ly/3DyjBBZ).
Jman
August 22, 2022
Can Theanine cause withdrawals if taken for 1 year+ and then stopping abruptly?
David Tomen
August 23, 2022
I have never heard of anyone going through withdrawal from stopping L-Theanine.
Andrew
August 18, 2022
David,
I normally consume a 200mg serving of caffeine in the morning. The literature I’ve seen online has pointed to a 2:1 L-Theanine to caffeine ratio.
This leads me to believe that to create the optimal synergistic effect of caffeine and L-Theanine I should be stacking 400mg daily of theanine at the time I consume the caffeine.
Do you have any input on this? If I consumed less than a 2:1 ratio of L-Theanine (say 250 – 300 mg) with the caffeine would that likely be sub-optimal?
Thank you David.
– Andrew
David Tomen
August 21, 2022
Andrew, it depends on your system. But even with caffeine, 250 – 300 mg L-Theanine will likely make you sleepy. The only way to find out is to try it. It would likely work better if you also supplemented with 250 mg L-Tyrosine and a BioActive B-Complex.
Alex
July 24, 2022
Hello David,
Can L-Theanine be taken with L-Tyrosine, or it’s better to take them apart?
Thanks.
David Tomen
July 24, 2022
Alex, I use both and it works great. L-Theanine may potentiate how well L-Tyrosine works.
Alex
July 24, 2022
David thanks a lot for your quick reply.
I would like to ask you one more thing as I really got confused after seeing these 2 research papers.
1. https://pubmed.ncbi.nlm.nih.gov/9614715/ Here they say that Theanine decreased Serotonine Levels in rats brain.
2. https://pubmed.ncbi.nlm.nih.gov/9566605/ And here they talk about possibility of increasing DA and Serotonin in rats brain.
It’s quite confusing and your opinion will be very interesting as I really don’t want to take any supplement which might decrease Serotonin levels as I think I already don’t have enough and taking every night 500 mg of Tryptophan.
David Tomen
July 26, 2022
Alex, the first study does not make any sense because the author is contradicting his claims in the Abstract. I haven’t read the entire study.
And the 2nd study concentrates primarily on dopamine. They also injected L-Theanine directly into the rat’s brain. Which is not the preferred method when using L-Theanine as a nootropic in humans.
I would not worry about suppressing serotonin if using L-Theanine. The bottom-line is “does it work for you?”. That’s more important than the science.
Alex
July 24, 2022
And I forgot to ask you, in compare to Tryptophan, L-Theanine doesn’t compete with Tyrosine crossing Blood-brain barrie right?
David Tomen
July 26, 2022
Not as far as I can tell. Both are generally used in high enough dosages that enough will get through to your brain to provide its benefit no matter how many different supplements you are using.
Susie Averbach
August 17, 2022
Hi David,
I’m really wanting to eliminate brain fog and increase memory. I take Mind Lab Pro, and am finding some subtle benefits, but I feel like I need extra support.
Would you suggest adding the Performance Lab Energy or the Multi now? I’m very sensitive to any supplements.
As always, thank you so much for your help- really appreciate it.
Susie
David Tomen
August 21, 2022
Susie, definitely both Performance Lab Energy and the Multi.
But it depends on your age. You need dopamine and acetylcholine for memory. There may not be enough L-Tyrosine or CDP-Choline in Mind Lab Pro to get the job done if you are older. Adding additional L-Tyrosine in the morning and at noon, and extra CDP-Choline and ALCAR at noon may help.
But brain fog can also be caused by things other than neurotransmitter dysfunction. See this article for more: https://nootropicsexpert.com/best-supplements-for-brain-fog/
Louis Williams
July 9, 2022
Hello – Could L-Theanine be taken long-term/forever?
Would you recommend any routine blood testing associated with taking the supplement?
David Tomen
July 10, 2022
Louis, there is no data telling us how long we can use most supplements. But L-Theanine is natural and as long as you have a healthy liver and kidneys you should be able to use it long-term.
These are most of the labs that make sense for assessing your general health: https://nootropicsexpert.com/neurohackers-guide-to-lab-tests/. Pay attention to the markers for liver and kidneys. Google “labs for liver health” and “labs for kidney health” to know what to look for.
Rasheed
June 27, 2022
David sorry I thought I was commenting on the supplement ( Mind life pro)
so my initial question for children is on this nootropic
David Tomen
June 27, 2022
Rasheed, Mind Lab Pro has not been tested for use with someone who is autistic. It is a two capsule dose so if you are going to try it start with one capsule and see how they feel.