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The Ultimate Guide To L-Theanine

L-Theanine is an active amino acid found mostly in green tea. It has great relaxing and calming effects and may help to support a healthy metabolism. It crosses the blood-brain barrier very easily, making it one of the top effective supplements for relaxation. L-theanine is non-sedating, meaning that you get the relaxing effects without feeling tired.

In this article, we’ll look into some of the scientific research about the positive effects of L-Theanine. We also explore the recommended dosage as well as any potential side effects from taking L-Theanine.  This is a great dietary supplement to support a relaxed mood.

pretty woman holding tea, l-theanine L-theanine is the active ingredient in tea, and goes really well with coffee (caffeine)

L-Theanine Is Backed Up By Science

Scientists are researching l-theanine for its effects in reducing stress and improving attention and focus. One of the best things about l-theanine is that it is very natural. Its effects are subtle yet effective. You’ll feel the effects are felt within an hour of taking the l-theanine, and it works really well when you combine it with caffeine.

There have been a number of recent studies into the beneficial effects of l-theanine supplements. Below, we’ll outline five of the top latest l-theanine studies:


  1. L-theanine For Stress


A 2016 study on 34 healthy adults found that l-theanine was effective at reducing the feeling of stress. This was a double-blind, placebo-controlled study (very good method). The researchers measured the stress response and cortisol (stress hormone) levels for the participants both before and 2 hours after taking l-theanine. They found that the stress and cortisol levels had significantly reduced after 2 hours.[1]


  1. L-theanine For Better Mood

Another study from 2016 indicated that l-theanine was effective at supporting a healthy mood and reducing stress levels. Twenty patients with major depressive disorder (MDD) were given 250mg of l-theanine daily over a period of 8 weeks. The research indicated that l-theanine may be an effective supplement for helping to improve mood, sleep, and cognition.[2]


  1. L-theanine For Better Sleep
Liftmode's L-Theanine 200mg

A recent review looked at a number of studies about using l-theanine for sleep. The studies used many different techniques to measure how l-theanine might improve sleep. These included different types of questionnaires and assessments, as well as actigraph (measuring rest and activity) studies.


The authors of the review found that l-theanine is effective at promoting healthy sleep, but without causing drowsiness. They thought that this might be due to l-theanine’s anti-stress effects.[3]


  1. L-theanine To Reduce Caffeine Jitters

A study from 2014 looked at the effects of combining l-theanine with caffeine. 24 volunteers participated in the study. The study found that using l-theanine with caffeine was a great way to eliminate the negative effects of caffeine (jitters).[4]


  1. L-theanine For Improved Cognition

man studying with l-theanine Studies have found that l-theanine may be beneficial at improving cognition

In 2014, researchers published a study comparing the effects of l-theanine to caffeine. The researchers measured participant’s alertness, calmness, and feeling of connectedness. They also used other tests to measure cognitive performance. They found that l-theanine and caffeine both improved cognition, although l-theanine was more subtle and slower acting than caffeine.[5]


Recommended Dosage

According to the studies that we’ve examined, the recommended dosage for l-theanine supplements is around 100-200 mg once or twice daily. However, some people choose to use higher doses without experiencing any negative side effects.


Side Effects and Warnings

The no adverse effects level for l-theanine is around 2000 mg [3]. This means that even using a dose as high as 2 grams, most users will not experience any negative effects. L-theanine is a natural and nonessential amino acid, meaning that it is produced in your body. It is highly regulated and is used for a number of functions – including to build proteins. L-theanine is a very safe supplement to use.[6]



lady enjoying tea, l-theanine L-theanine is a great relaxing supplement with mood-lifting effects

In conclusion, we’ve found that l-theanine is a safe and effective supplement. You can use l-theanine to improve your mood, focus, and sleeping patterns. L-theanine goes really well with caffeine and might also be able to help prevent some of the negative effects of alcohol. L-theanine is a nonessential amino acid and is a very safe supplement to take, with no observable negative effects even at high doses.




[1] Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial, DJ White et al., Nutrients. 2016 Jan 19;8(1). pii: E53. doi: 10.3390/nu8010053.

[2] Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study, S Hidese et al., Acta Neuropsychiatr. 2016 Jul 11:1-8. [Epub ahead of print]

[3] In Search of a Safe Natural Sleep Aid, TP Rao et al., J Am Coll Nutr. 2015;34(5):436-47. doi: 10.1080/07315724.2014.926153. Epub 2015 Mar 11.

[4] A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood, FL Dodd et al., Psychopharmacology (Berl). 2015 Jul;232(14):2563-76. doi: 10.1007/s0021 polre ffects of alcohol. is usecalm, relaxed state and a healthy mood. ng l-theanine. We also expolre ffects of alcohol. is use2015 Mar 13.

[5] Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis, DA Camfield et al., Nutr Rev. 2014 Aug;72(8):507-22. doi: 10.1111/nure.12120. Epub 2014 Jun 19

[6] Theanine, Examine.com, retrieved on October 28, 2016