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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
Alexandra
May 27, 2020
Dear David,
Thank you for this article. I adopted my daughter at birth (she is 2 years old now) and was prenatally exposed to methamphetamine through the 2nd and 3rd trimester. She is still very young and we have a long healing journey ahead of us but Im wondering if you believe giving L-Theanine might be useful given its modulating affect on Dopamine?
If you think any other supplements might be useful, I’d be so appreciative. She is young which for me feels like such a powerful opportunity to help her brain heal to the extent that it can.
David Tomen
May 28, 2020
Alexandra, L-Theanine may be helpful but I’m the wrong person to ask. This needs to be answered by a doctor or other medical professional who knows about or specializes in adolescent brain health.
Because each of the nootropics I review and write about here on Nootropics Expert are very powerful compounds. And I do everything I can to research effective dosages and Side Effects for adults. We always caution anyone under the age of 21 when using any of these supplements. Children, and esp. young children are a completely different specialty. Particularly when it comes to cognitive health.
Colleen
May 19, 2020
Hi David, do you have any thoughts on cycling L-Theanine? I’ve been taking it on work days and cycling off at weekends to help boost cognitive function and reduce anxiety for work while avoiding building up a tolerance to it. However, I’m not sure if this is actually necessary and if it’d be more beneficial to simply take L-Theanine every day. Thanks 🙂
David Tomen
May 19, 2020
Colleen, I’ve never heard of nor come across in any of the research I’ve done the need to cycle L-Theanine. As long as you’re using it within the parameters of recommended dosages you should not have a problem using it daily.
I personally use it daily primarily late in the evening because I sleep better. When I’ve used it during the day it’s with caffeine as in Performance Lab Stim. I’ve found using L-Theanine on its own early in the day causes fatigue.
Colleen McCaskell
May 23, 2020
Hi David, thanks very much for the response. I’ve typically been taking it midday so I’ll experiment with taking it in the evening and see what the results are like!
DeRichia Henderson
April 27, 2020
Hi David
First, thank you! for all of your videos they have truly been my go to! I’m taking L Theanine for anxiety and it has been a big help. I would like to know what I can stack it with for Depression I’m not on any other meds as I refused them for alternatives as I’m glad so far that I did. You stressed 5htp as NOT being a good option. What about Ashwaghanda or otherwise? If so please advise based on your expertise?
David Tomen
April 28, 2020
DeRishia, Aswagandha is a good start. But it all depends on the root cause of your depression. See this post for a more detailed explanation and what your options are: https://nootropicsexpert.com/best-nootropics-for-depression/
Eddie
April 2, 2020
Hi David, is there a supplement that will help me metabolize the caffeine out of my system when I drink a caffeinated beverage in the afternoon? I used to be able to drink caffeinated beverages any time of day when I was younger with no effects. Now as I have gotten older, when I have caffeine in the afternoons, I have trouble going to sleep. Thanks.
David Tomen
April 23, 2020
Eddie, there is nothing to will help flush out caffeine on demand. Only option is to avoid using it too late in the day.
Antheia
March 9, 2020
Hi there, thank you for the great information in this post. I was excited to try l-theanine, mainly for the memory enhancing and stress-busting effects. I also take a range of vitamins and minerals and additional NAC and lysine. I take Ashwagandha every second day and Rhodiola every other day (mostly a cost issue) and I recently added lion’s mane.
I started the l-theanine on 200mg just in the morning and had the worst headache ever. Like a 10x migraine. I stopped taking it for a week and the headache went down to my normal daily level and then I tried it again and had the same response. So I am guessing that it was the l-theanine that was the cause.
I am gutted about this as I really would like the benefits and I do want to understand where the problem is so that I can make better supplement decisions. I have low motivation and concentration and memory issues and this seemed like a great addition.
Do you think it is the l-theanine that is causing the issue? And if it is, is there a likely reason? (I am based in the UK)
David Tomen
March 9, 2020
Antheia, that’s one side effect that should NOT happen with L-Theanine. Because I don’t see how it could. Even considering the other supplements you’re using.
There must be something else in that supplement to cause that to happen. What does the label say? Are there any other ingredients?
Maria Atzeva
March 7, 2020
Hi David,
I am going for Ketamine Assisted Psychotherapy do you have any information on that therapy for depression and can I continue to take my L Theanine 2x250mg per day?
Thank you
David Tomen
March 7, 2020
Maria, I’m not aware of any contraindication between L-Theanine and Ketamine. But I suggest checking with your doctor. This is the list of contraindications for Ketamine: https://www.drugs.com/drug-interactions/ketamine-index.html
Brigitte
March 9, 2020
Hi, just to tell you ketamine has worked fantastically for me, it wiped my depression off in a durable manner. However it had slight side effects on my focus and short term memory. Nothing alarming but I could feel the difference, and it only slowy came back to order when the trial ended and I stopped the injection. At the time I didn’t take L-theanine to support my brain but I would try it now if I had to do it again as I didn’t like this feeling although all in all it was a very positive experience. Good luck with it.
Wim
February 2, 2020
Hi David,
I started L-Theanine some months ago, to cope with stress.
about an 30-60min after taking it sharped focus and calmed.
I started to use it regularly and sometimes more pills in the same day when needed & combined with CBD for the same effect.
Still had that pressure in the chest that mounted up over time. Now I know it was from to much norepinephrine buildup from other supplements (curcumin+peperine, ALA and I think L-Theanine was the drop in the bucket that made it overflow. )
This old research from 1986 https://www.jstage.jst.go.jp/article/cpb1958/34/7/34_7_3053/_article “in the brain of rats with or without coadministration of caffeine were investigated, and compared with those of glutamine. Theanine decreased the norepinephrine (NE) level”
“In rats pretreated with pargline, a monoamine oxidase inhibitor, theanine significantly increased the NE level compared with the control.”
David does this mean when NE level is normal, L-Theanine decreases it.
But when NE level is high due to a MAOi , it gets even higher?
this 2018 study: https://www.ncbi.nlm.nih.gov/pubmed/30474152
In the PFC, NAC, and HIP, L-theanine administration significantly increased the levels of 5-HT, NE, and DA. In the ST, the levels of 5-HT and DA were increased after the administration of L-theanine. However, in the HIP, only the level of DA significantly changed after the treatment of L-theanine.
(both studies are on rats but no human studies could be found)
David, does both studies mean that :
1) in normal NE levels, L-Theanine just will counter the NE increase by Caffeine?
2) in high NE levels due to MAOi or stress, L-Theanine increases the NE even more?
thanks in advance
David Tomen
February 2, 2020
Wim, in all the major studies I’ve looked at L-Theanine helps increase serotonin, GABA and dopamine. There is no mention of norepinephrine in these studies.
Jay LIM
January 10, 2020
Hi David. Thank you for the good post.
I’ve been doing ‘Intermittent fasting'(16 to 24 hour everyday) for about 2years. I have a question. Does L-theanine supplement (400mg) break a fast? I think it may contain calories because it is a kind of amino acid. If it has calories and changes insulin levels a little, then I’m going to adjust the time I take the L-theanine supplement to keep my fasting going.
Thank you in advance for your reply.
David Tomen
January 11, 2020
Jay, as far as I can tell L-Theanine will not break ketosis if you’re fasting. But if you’re worried about it just make sure to supplement with a high quality MCT Oil like the new Performance Lab MCT which will provide the extra ketones just in case.