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L-Theanine Effects: The Top 5 Uses Explained!

L-Theanine is an active amino acid found mostly in green tea. L-Theanine effects include great relaxing and calming effects and it 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 Effects Are Backed Up By Science

Scientists are researching L-Theanine effects for reducing stress and improving attention and focus. One of the best things about this naturally-derived supplement is that it is easy to use and highly beneficial. L-Theanine 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 studies examining the top 5 L-Theanine effects:


  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 the top L-Theanine effects may include helping people 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 the L-Theanine effects on sleep and rest. 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 without causing drowsiness. They thought that this might be due to L-Theanine’s potent 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 some of the negative effects of caffeine (like 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 L-Theanine effects to the effects of caffeine. The researchers measured participants' 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 maximum "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]


Conclusion: The Top L-Theanine Effects

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