L-theanine is one of the most commonly used nootropics. It's very safe, is effective on its own, and stacks well with many other smart drugs.

Used for its calming effects, L-theanine can reduce anxiety without causing sedation. This makes it a valuable tool in any nootropic user's arsenal.

We're going to take an in-depth look at L-theanine, its benefits, how it's used, what it stacks well with, and where to buy it. But first, let's see what exactly L-theanine is.

What is L-theanine?

L-theanine (often just called theanine) is a non-essential amino acid that is found naturally in green tea.¹ Though it has a number of effects on our bodies and brains, we don't need it to survive. While L-theanine is found in green tea, it doesn't contain enough for most people to notice much of an effect. One cup of green tea contains about 20 mg of L-theanine.² But when taken in higher amounts, its effects can be very noticeable. 

Several scientific studies have shown that L-theanine is able to reduce anxiety without causing sedation. One study using electroencephalography (EEG) found that L-theanine, at a dose of 200 mg, increased alpha waves in several parts of the brain.³ Alpha waves are associated with being calm, yet awake and alert.

Another study found that, even at a dose of 50 mg, L-theanine increased alpha waves in certain parts of the brain.⁴ That means that, even though they might not be felt, L-theanine is still having a calming effect at lower doses.

When healthy volunteers were given 200 mg of L-theanine and asked to complete various tasks, those more likely to get anxious displayed increased visual performance and improved reaction time.⁵ The volunteers who rarely experienced anxiety didn't show much improvement.

This is consistent with countless anecdotal reports from around the internet. People who suffer from anxiety often report that L-theanine improves their performance and makes them feel less anxious, but without causing sedation. Many prescription anxiolytics (anxiety-reducing substances) are sedating and can be habit forming. Because of this, a lot of people who suffer from anxiety don't like to use them. L-theanine, for many people, is a safer, just-as-effective alternative.

There has only been one study done comparing L-theanine to a prescription anxiolytic.⁶ Researchers gave participants either L-theanine or alprazolam (Xanax), then assessed them during relaxed and anxious conditions. They found that only the L-theanine had a calming effect during normal, relaxed conditions but neither of them did during artificially-created stressful conditions. That means that L-theanine was more effective than Xanax at promoting a sense of calmness during normal conditions.

Another study showed that L-theanine reduced the participants stress response when given mental tasks to complete.⁷ Researchers found a decrease in both psychological and physiological stress responses among people who took 200 mg of L-theanine. Not only did the participants self-report feeling less stressed when completing the tasks, their heart rates did not elevate as high as they did in the people who didn't take L-theanine.

All of these studies are consistent with what people in the nootropics community have reported. And L-theanine has been shown to be extremely safe. It has been classified as GRAS (Generally Regarded As Safe) by the FDA.⁸ A 13-week animal study done to test the safety of L-theanine found no adverse effects at all, even at incredibly-high daily dosages (equivalent to a human dosage of about 320,000 mg/day).⁹

L-theanine benefits

• Reduced anxiety
• Improved mood
• Fall asleep faster
• Better sleep quality
• Reduces side effects of caffeine (jitters, crash, anxiety)
• Stacks well with most other nootropics

How to take L-theanine

By itself for anxiety and sleep

A lot of people take L-theanine by itself for its calming, anxiety-reducing effect. For this purpose, dosages of 100-400 mg are typically used. Others take it to promote deep, restful sleep.

A study done on boys with attention deficit hyperactivity disorder (ADHD) found that L-theanine improved several aspects of sleep quality.¹⁰ The boys given L-theanine had significantly higher sleep percentage and sleep efficiency scores.

This study is consistent with countless anecdotal reports. Many people report that taking L-theanine before bed helps them fall asleep faster, sleep better, and wake up feeling more rested. Some people find that as little as 200 mg works while others take over 1,000 mg to improve their sleep.

L-theanine can be taken with or without food.¹¹ The absorption of many substances can be affected by how much you've got in your stomach but L-theanine isn't one of them. This makes it convenient to take at any time.

With caffeine for calm focus

The most popular way to take L-theanine is with caffeine. This is also likely the most common nootropic stack being used today.

L-theanine can reduce or even eliminate caffeine's side effects, including restlessness (jitters) and anxiety, without causing sedation. When taken together, users often report a calm sense of focus. This combination has been the subject of several scientific studies.

When researchers gave 20 healthy volunteers either L-theanine, caffeine, both, or placebo, the participants in the group receiving both showed the most improvement in attention.¹² People taking L-theanine or caffeine by themselves also showed improvement, but not as much. This shows that caffeine and L-theanine have a synergistic effect.

Another study found similar results.¹³ Participants given L-theanine and caffeine showed objectively faster reaction times, faster working memory reaction time, and improved sentence verification accuracy. They also reported subjectively feeling less tired and more alert.

A meta-analysis, which looked at the results of several studies, also found L-theanine and caffeine to improve several aspects of cognitive functioning.¹⁴ It found that this combination showed significant improvement inattention, especially in the first two hours after consumed.

Caffeine and L-theanine together make a simple yet effective nootropic stack. Users often report all the benefits of caffeine (increased wakefulness, improved attention, etc.) with none of the side effects (jitters, crash, anxiety, etc.). You can learn more about this simple nootropic stack here: L-Theanine and Caffeine – A Winning Combination.

As part of a nootropic stack

Many nootropic users include L-theanine in their stacks. While there hasn't been any scientific studies on the way L-theanine interacts with most nootropics, there are plenty of case reports to support its use.

Some people like to add L-theanine to nootropic stacks that contain modafinil or one-or-more racetams. They often report that taking L-theanine with them improves their effects.

And a lot of nootropic blends contain L-theanine. Due to its excellent safety profile and all the research that has shown its effectiveness, L-theanine is often included in premade nootropic products.

Where to buy L-theanine

L-theanine is one of the most commonly-used nootropics and there are a number of places to buy it. Amazon sells a number of different brands, as well as several nootropic blends that contain L-theanine. It is very inexpensive which, when combined with its safety and effectiveness, explains why L-theanine is so popular.

There are a number of brands to choose from. My personal favorite, which I've ordered several times, is this one. It contains Suntheanine, a patented form of L-theanine which has been extensively studied.

Many users prefer to buy their nootropics in powder form. Bulk Supplements, a well-known and respected supplement manufacturer, offers L-theanine in powder form at a very-reasonable price.

Most online nootropic vendors also sell L-theanine. Some products contain only L-theanine while others contain both L-theanine and caffeine. Pure Nootropics offers an awesome caffeine and L-theanine combo that I love. The ratio of caffeine to L-theanine is perfect. If you're looking for a product that contains both L-theanine and caffeine, I strongly recommend this one. 

Conclusion

After seeing all the science to support L-theanine's safety and effectiveness, it's no surprise it's as popular as it is. This amino acid is widely used by itself and as part of various nootropic stacks.

If you're looking to reduce anxiety and experience a calm sense of focus, L-theanine can be an excellent choice. It can also be effective at helping you sleep better. With such an excellent safety profile, L-theanine makes for a great first nootropic. People who are new to nootropics and experienced users alike all can all enjoy its benefits.

L-theanine, being as safe and effective as it is, has made it onto several of our lists. Here are just some of them:

The Top 5 Calming Nootropics

The 6 Most Effective Nootropics

The Best Nootropics For Social Anxiety

References 

^{1. Theanine. (n.d.) Wikipedia. Retrieved November 23, 2018 from https://en.wikipedia.org/wiki/Theanine ↩}

^{2. Boros, K., Jedlinszki, N., & Csupor, D. (2016). Theanine and caffeine content of infusions prepared from commercial tea samples. Pharmacognosy Magazine, 12(45):75-9. ↩}

^{3. Kobayashi, K., Nagato, Y., Aoi, N., Juneja, L.R. et al. (1998). Effects of l-theanine on the release of alpha brain waves in human volunteers. Nippon Nogeikagaku Kaishi, 72(2):153-7. ↩}

^{4. Nobre, A., Rao, A., & Owen, G. (2008). L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr, 17(S1):167-8. ↩}

^{5. Higashiyama, A., Htay, H., Ozeki, M., Juneja, L., et al. (2011). Effects of l-theanine on attention and reaction time response. Journal of Functional Foods, 3(3):171-8. ↩}

^{6. Lu, K., Gray, M., Oliver, C., Liley, D., Harrison, B., et al. (2004). The acute effects of l-theanine in comparison with alprazolam on anticipatory anxiety in humans. Human Psychopharmacology, 19: 457-65. ↩}

^{7. Kimura, K., Ozeki, M., Juneja, L., & Ohira, H. (2007). L-theanine reduces psychological and physiological stress responses. Biological Psychology, 74(39-45). ↩}

^{8. Food and Drug Administration (2006). L-theanine GRAS Notice. Retrieved November 23, 2018 from https://www.accessdata.fda.gov/scripts/fdcc/index.cfm?set=GrASNotices&id=209 ↩}

^{9. Borzelleca, J.F., Peters, D., & Hall, W. (2006). A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats. Food Chem Toxicol. 44(7):1158-66. ↩}

^{10. Lyon, M.R., Kapoor, M.P., & Juneja, L.R. (2011). 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. Alternative Medicine Review, 16(4):348-54. ↩}

^{11. Brooks, M. (2018, February). How l-theanine will change your morning coffee forever. Retrieved on November 24, 2018 from https://medium.com/@Misiahb/how-l-theanine-will-change-your-morning-coffee-forever-9768a4f9ceea ↩}

^{12. Kahathuduwa, C.N., Dassanayake, T.L., Amarakoon, A.M.T., & Weerasinghe, V.S. (2017). Acute effects of theanine, caffeine, and theanine-caffeine combination on attention. Nutritional Neuroscience, 20(6):369-77. ↩}

^{13. Haskell, C.F., Kennedy, D.O., Milne, A.L., Wesnes, K.A., & Scholey, A.B. (2008). The effects of l-theanine, caffeine and their combination on cognition and mood. Biological Psychology, 77(2):113-22. ↩}

^{14. Camfield, D.A., Stough, C., Farrimond, J., & Scholey, A.B. (2014). Acute effects of tea constituents l-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutrition Reviews, 72(8):507-22. ↩}

[This article was originally published on December 8, 2018. Updated March 24, 2023.]