4.0 /10


5.0 /10


4.0 /10


Anxiety Support
Improve Focus
Improve Memory
Sleep Quality
Mood Support



L-Theanine is an amino acid not usually found in the diet. Also known as Suntheanine – this supplement is what gives tea its calming effects. It promotes relaxation without being sedative, meaning it will not induce drowsiness, yet will result in a calm, focused state of mind. This amino acid is one of the few supplements that is able to pass the blood-brain barrier, which enables it to induce profound effects. Note that it is the amino acid analog of the proteinogenic amino acid known as L-glutamate, which is found in fungal species and other plants.

It was originally discovered in green tea in the 1950s and isolated from gyokuro leaves. It is known to be the ingredient responsible for the great impact on mood that black and green tea have. By subtly altering the brains neurotransmitters, it produces a calming effect that allows you to counter the stimulating effects of Caffeine within tea. L-Theanine and caffeine work together to promote concentration and allow people to remain calm and alert. On its own, an L-Theanine dosage helps to promote alertness, concentration, reduces stress and is also known to improve the quality of sleep[14].

Benefits and Effects

In a study conducted on the effects of L-Theanine on stress and anxiety, there were two sets of people, those who took L-Theanine and others who took a placebo. Patients who took the amino acid experienced L-Theanine benefits such as lower stress symptoms, reduced blood pressure, and lower heart rate. In patients with schizophrenia, there was a significant reduction in anxiety levels. Patients who do not suffer from any anxiety disorder experienced an increase in relaxation even though it does not feel the same as a sedative.

Theanine helps promote relaxation on a cerebral level by helping the brain relax [2]. It does so by promoting healthy cortisol levels. [3,5]. Theanine has also been shown to help enhance a persons sense of well-being as well [1].

Cognitive Benefits

L-Theanine promotes healthy memory function and focus [7]. It does so by supplementing Alpha-1 brain activity [7]. Elevated Alpha brain wave activity benefits focus, cognitive performance, learning abilities, and even promotes creativity [4,5]. L-theanine supplements memory storage as well as it promotes healthy neurons, a process known as neurogenesis [10].

The substance is also known for increasing memory and improving attention. People who have brain damage have shown an improvement in memory, especially when they take it with tea extracts. During one particular study, it was noted that patients experienced improved alertness and attention span with healthy individuals showing an enhancement in attention and concentration[12].

Caffeine is known to have some negative effects on the cognitive functions of individuals. However, L-Theanine helps to reduce some of these effects. It also works to improve alertness and reduce fatigue in healthy individuals. High dosages of caffeine- above three cups of coffee, are known to cause an increase in blood pressure and heighten jitters. This supplement can reduce blood pressure. These were seen in studies conducted in rats and some that were done on human beings. The jitters caused by caffeine were significantly reduced and patients with blood pressure issues had it managed[16].

It is also shown to significantly improve the blood vessel functions. Also, it is known to reduce low-density lipoprotein, which is known to cause the hardening of arteries in the body. It also restores the antioxidant capabilities of liver cells, thus reducing instances oxidative organ damage. There is a reduction in oxidative damage and inflammation, especially when one takes a dose independently[12].

ADHD is a condition that is known to increase insomnia and reduces the quality of sleep in individuals. In a certain study, boys who took 200mg of L-Theanine capsules daily for six weeks experienced an improved sleep quality as compared to patients who took a placebo.

L-Theanine for Sleep

This powerful amino acid may be helpful for those struggling with sleep quality. L-theanine does not cause sleepiness and fatigue because it is not sedative by nature; however, research suggests that supplementation can promote sleep quality [8]. Studies point to a decrease in sleep activity, such as tossing and turning, when supplementing with Theanine [8]. Users have reported feeling as if they have slept more than they actually have if supplementation preceded sleep [8].*

In a study conducted on children, it was shown that the quality of sleep was much higher, although it did not affect latency and sleep durations. Despite the relaxation effects, it seems contradictory that this supplement improves concentration spans in individuals. This is one of the reasons why most people turn to nootropics, which is great especially because many of them are natural [1].

Exercise Performance

Healthy blood flow is one of the benefits that usually come with supplementing with L-theanine [9]. The ability to benefit focus and alertness makes caffeine  theanine a solid alternative to traditional pre-workout formulas.

How Much L-Theanine in Green Tea

According to research, four cups of green tea contain between 60 and 160 milligrams of L-Theanine. A study found that taking such a quantity of green tea improves focus, especially when handling complicated tasks. The suggested ratio of L-Theanine to green tea is 2:1 [14].


The L-Theanine maximum dosage is 300mg per day. If you are taking L-Theanine max dosage, you need to cycle to ensure that you do not get any adverse effects from prolonged use. However, you may opt to take a smaller dosage of the L-Theanine best brand 50mg to 200mg per day is enough to get you the brain boost you need. However, the dosage you get will depends on your personal biochemistry. In caffeine, there is about 100mg [12].

When given in lower dosages, it has a stimulating effect. For stimulation, the dosages offered are less than half of those that promote relaxation [15].

Side Effects

L-theannine does not have any known negative effects. However, there have been reports of people experiencing diarrhoea and nausea after taking high dosages of L-Theanine for weight loss. The supplement is not recommended for people who are already taking blood pressure medication or who suffer from low blood pressure.


L-Theanine and Caffeine Stack

Caffeine is known for promoting alertness and combating fatigue with research showing that it also benefits reaction time as well as the ability to process information. However, it can leave one feeling jittery or scatterbrained. L-Theanine helps to eliminate these downfalls while actually augmenting the positive effects of caffeine.

A study observing the cognitive benefits of caffeine vs. caffeine theanine indicates that combining the two supplements results in enhanced mental performance in speed and accuracy tests while reducing susceptibility to distractions [6]. In addition, the L-Theanine and Caffeine combination benefits an individual’s performance when attempting to surmount a cognitively demanding task, while caffeine without l-theanine can decrease performance.

L-Theanine has many positive documented mental performances when stacked with caffeine. Stacking caffeine and L-Theanine has synergetic effects that increase attention and cognition. It is, therefore, the most popular choice for the people who are looking to get a cognitive boost without increasing costs. [16].

L-Theanine And Nootropics

It can also be stacked with other nootropics to help increase your cognitive functions, making it easier for you to concentrate, and increase your attention span. It also keeps you calm and helps you keep your mood stable and happy[11].


“I take my nootropics in powder form with water. I don’t mind the taste of most, but caffeine is nasty (PEA is worse), so theanine is a MUST for two reasons: 1. to offset unwanted side effects of caffeine/stimulants. 2. the sweet taste of Theanine offsets the bitter taste of caffeine or any other not-so-tasty powders I imbibe. (There are more than 2 reasons to take Theanine, but you probably already know those if you’re on this page and considering ordering.)”– James

“This is my 2nd time getting this I really enjoy it before I take PEA or really any supplement that gives me a peppy boost this helps everything to be more relaxing enjoyable with no jitters or tension, it also goes well with any product that has caffeine thanks Powdercity have a wonderful Holiday season went above and beyond to make sure I received my latest order before Christmas.” Brent R.

“I cannot stress enough how great this product is. This compound is a great additive to any of my daily stacks. I find that taking it like a vitamin helps keep an even flow, but it helps to simply just add it to any stimulants to smooth them out, helping me be focused. I can get to sleep easier at the end of the day though too, with or without GABA, but I take a strong GABA dose before bed if I don’t have a small Phenibut dose on hand.”  Michael C.

“This was the first order I placed with PC. My caffeine tolerance was super high relative to the benefits I was receiving. L-Theanine, allowed me to reduce my caffeine intake and use caffeine more productively. I’ve read reports that tolerance builds and it doesn’t work as powerfully as it once did. I have found that a few minutes of meditation shortly after ingesting, kick starts the theta cycle returning the focus and concentration benefits.” Jess C.

“Theanine is a great and inexpensive addition to a speedy stack. Where before I would have difficulty getting to sleep with energy boosters, this makes it more manageable and balanced. I found that it kept me from getting too wound up, and allowed me to pace my racing thoughts better. Improved the performance of my memory and attention (which complimented each other), so that I was still energized and focused, but remained calm and in control.” Travis R.

“Researched multiple articles and tons of reviews for this product before trying it. Going on my 4th week taking 100mg in the morning and it still gets the job done! Makes me feel more calm especially in stressful situations (like when I had my job interview) and I feel way more focused in the gym (haven’t had one bad workout). I will say that I take it with ALCAR(500mg) and dicaffeine (100mg) to enhance my overall mental focus and physical performance and this combo great (mild energy rush, neutralized jittery effects, feeling of finally being awake, and imo decreased cortisol levels in the morning and after the gym). Definitely will buy as long as I can. And all bias opinions aside, for this price, the quality, and the speed of shipping, I very much recommend this product from powdercity, you can’t beat it.” Nick F.

“It’s been helping me fall asleep much faster and easier at night. Most of the time if I take a big dose it will knock me out but without making me feel groggy or tired when I wake up. L-theanine works much better than melatonin or L-tryptophan for me put me to sleep. I imagine a combination of L-theanine & L-tryptophan would be a good sleep aide combination. I’ll also take L-theanine to get rid of the jitters if I overdo it on my caffeine intake as well. For the price of L-theanine it’s definitely worth the money…” Mike

Additional information

Weight0.101 kg


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1. http://www.ncbi.nlm.nih.gov/pubmed/1637346

2. http://espace.library.uq.edu.au/view/UQ:284103

3. http://www.ncbi.nlm.nih.gov/pubmed/16930802Show less

4. http://www.ncbi.nlm.nih.gov/pubmed/17272967

5. http://www.ncbi.nlm.nih.gov/pubmed/23458739

6. http://www.ncbi.nlm.nih.gov/pubmed/18681988

7. http://www.ncbi.nlm.nih.gov/pubmed/21303262

8. http://www.ncbi.nlm.nih.gov/pubmed/22214254

9. http://www.ncbi.nlm.nih.gov/pubmed/22819553

10. http://www.ncbi.nlm.nih.gov/pubmed/18006208

11. https://www.drugs.com/npc/ltheanine.html

12. https://examine.com/supplements/theanine/

13. http://www.berkeleywellness.com/supplements/other-supplements/article/theanine-calmness-pill

14. https://www.nootropedia.com/l-theanine/

15. https://selfhacked.com/blog/theanine/

16. https://88herbs.com/l-theanine-caffeine/

Also known as:Theanine, 5-N-Ethyl-Glutamine
Good for: , , , , , , ,
Stacks well with: Caffeine
Typical dose:50 - 100 mg per day
Half Life :2.5 - 4.5 Hours


Anxiety Support
Improve Focus
Improve Memory
Sleep Quality
Mood Support