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  • Promotes relaxation without drowsiness
  • Improves mood and focus, especially when used with caffeine
  • Multiple health-promoting effects


L-theanine is a calming and focusing non-dietary amino acid that is uncommon in food sources and is found primarily in green tea. It is most commonly used for its relaxing and mildly stimulating effects but has also been found to increase mood and focus, improve sleep quality and have other health promoting effects. Recommended dosage is 100-200 mg once or twice daily. There is hardly any evidence of side effects from L-Theanine use.


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L-Theanine reviews


“I am always experimenting with natural remedies. I found that L-Theanine and Phenibut work synergistically to completely eliminate stress. Liftmode's products have done what only toxic and very addictive substances have been able to do in the past. Allow me to socialize and live life comfortably...


John R.”

- L-Theanine review on Amazon.com


“I have had trouble with [attention] and [not] being able to focus during my college lectures. I also suffer from [stress] and...I take about 400 mg of L-Theanine a day (200mg doses). With my coffee when I wake up, and right before bed. It helps me to think clearly without the [stress], and helps me get a good night’s rest. I wake up earlier than my alarm clock now, because my body is fully rested throughout the night. I used to wake up feeling groggy and sleep deprived.

As for my mood, it is definitely better when I take it in the morning…I would definitely recommend this product.”

- Jelly Bean, Liftmode L-Theanine review on Amazon.com


L-theanine product reviews


  • L-theanine is a calming and focusing nonessential amino acid that is uncommon in diet and is found primarily in green tea
  • It is most commonly used for it’s relaxing and mildly stimulating effects but has also been found to increase mood and focus, improve sleep quality and have other health-promoting effects
  • Recommended usage is 100-200 mg once or twice daily
  • There is hardly any evidence of side effects from L-theanine use




L-Theanine (also known as Theanine or 5-N-Ethyl-Glutamine) is a relatively rare phytochemical found in a few species of tea and mushrooms. It is especially associated with Green Tea, where it plays a part in some of the tea’s flavour. L-Theanine is an uncommon amino acid and does not take part in forming proteins. Instead, it is used as a neurotransmitter and has effects on the brain and body.[1]


L-Theanine is very similar in structure to glutamine and GABA. L-Theanine is typically thought of as a relaxing agent that manages to produce a state of relaxation without promoting drowsiness. Furthermore, Theanine is a powerful natural stress-reducing agent that may also improve cognitive performance (like attention, focus, and memory). Although studies have not yet been conclusive in showing that L-Theanine is a natural sleep aid, it may help to promote sleep (so it doesn’t make you fall asleep, but does help to promote healthier, calmer sleep).


An interesting fact about L-Theanine is that it may be able to alter the perception of taste in a number of plant species where it occurs naturally. Research points to L-Theanine being able to help reduce sensations on bitter taste nodes when it occurs naturally (in chocolate, zinc, tea, and grapefruit). L-Theanine is associated with the taste of umami.[2]


Green tea has been used throughout the world, especially in the East, for thousands of years, and has long been known to have positive effects on human health. In fact, in 600 A.D., a Chinese writer called Lu Yu wrote a book called the Cha Jing (the Tea Classic), documenting some of the known history of green tea and how the perfect cup should be created.[3] It wasn’t until much more recently that we discovered the chemical constituents of tea and their potential benefits on human health!


L-theanine is presently being studied for a number of health benefits including stress reduction, improved mood and focus, better sleep quality and a variety of secondary health benefits. See this excerpt below, from the Memorial Sloan-Kettering Cancer Center’s piece on L-Theanine:


“[L-theanine] is consumed for its perceived antioxidant and relaxant effects. Several in vitro and animal studies have shown that L-theanine has lipid-lowering, neuroprotective, antiobesity, and antitumor properties.”[4]


L-Theanine Effects / Benefits

L-Theanine has a wide range of health benefits. Below, we’ll briefly explore the top five L-Theanine benefits, but remember that there is continuously more research being conducted on this fine natural supplement. It is quite possible that there may be more benefits discovered relating to L-Theanine in the very near future, but for now, these are the best-established benefits:


1.         Helps to Reduce Feelings of Stress & Promotes Relaxation


One of the most important effects of L-Theanine supplements is the ability to help reduce feelings of stress. In a study dated from 2004, the effects of L-Theanine were compared to those of a commonly prescribed anxiolytic (anti-anxiety) medication in 16 volunteers. L-Theanine was found to reduce baseline stress levels by creating a calmer and relaxed feeling in those who took it, while the common anxiolytic compound had no effect on baseline stress levels.[5] Stress is often related to mood and so it follows that L-Theanine has also been shown to have potent mood-enhancing effects.


L-Theanine has been directly shown in a number of studies to increase the activity of alpha-brainwaves.[6] Enhanced alpha brainwaves are associated with a relaxed mental state, without drowsiness (as reported by participants involved in alpha-wave studies). Alpha brainwaves are also known to exert a positive influence on attention and arousal.[7]


In a 2007 study, researchers conducted a double-blind study on twelve participants who underwent four separate trials, each involving L-Theanine or placebo. The participants were asked to perform a number of arithmetic tasks, designed to induce stress. Results of the study showed that L-Theanine supplements helped to reduce heart rate as well as salivary immunoglobulin A (s-IgA), which is a strong indicator of stress. The authors suggested that L-Theanine could reduce feelings of stress via the inhibition of cortical neuron excitation.[8]


2.         Helps to Boost Cognitive Performance


The structure of L-Theanine is highly similar to glutamate - a molecule known for its function in memory. It is able to penetrate through the blood-brain barrier and has been shown to protect neurons (brain cells) from damage and decay. Other studies have shown that L-theanine effectively increases brain serotonin, dopamine, and GABA levels[9] – all very important neurotransmitters involved in the maintenance of mood, rest, and emotions.


Increases in these brain chemicals are associated with increases in mood, attention, and relaxation. In both the East and the West, it has been known for a long time that drinking tea helps with managing stress. At least one scientific study has backed up this claim and shown that L-Theanine is able to reduce the effects of both psychological and physical stress.[10]


There has been a lot of research into the effects of L-Theanine when combined with caffeine, and they tend to show that the combination boosts both mood and brain power.[11]  One double-blind placebo study (the most acknowledged type in science) on 44 young adults and their response to a difficult cognitive task showed that L-theanine, in combination with caffeine, was able to increase alertness and boost brain power.[12]


3.         Helps to Improve Sleep Quality


There is evidence that L-Theanine supplementation can significantly improve sleep quality. In a 2011 study on male children with attention-deficit/hyperactivity (ADHD) disorder, it was found that daily supplementation of 400mg L-theanine significantly improved sleep quality over a six-week period.[13] 98 boys aged 8-12 years old and previously diagnosed with ADHD were given L-theanine or placebo over 6 weeks. Their sleep quality was monitored for five nights at the start and end of the period using wrist actigraphy and a Sleep Questionnaire completed by parents.


A second test, also in Japan, on 22 healthy young men over a 6-day period, found that L-theanine was a safe and effective supplement for the improvement of sleep and also for reducing nightmares.[14] Sleep quality was assessed using wrist actigraphy and questionnaires. In these studies, it is important to note that, although sleep quality was improved, two factors relating to sleep were not affected: sleep latency (time taken to fall asleep) and sleep duration.[15]


4.         Has a Highly Synergistic Relationship with Caffeine


Recently, studies have shown that adding L-Theanine to Caffeine helps to beneficially influence accuracy and attention and to significantly improve cognitive performance when compared to using Caffeine alone. The studies have been replicated using a similar L-Theanine dosage, and have come to the same conclusions.


These results are important and interesting because Caffeine use alone is known to increase cognitive performance as well as attention and memory. The addition of L-Theanine, however, seems to greatly improve these well-known Caffeine benefits. For example, a recent study found that adding 250mg L-Theanine to 150mg anhydrous Caffeine resulted in an improvement in reaction time and alertness with fewer complaints of caffeine-associated headaches.[16]


5.         Other Health Benefits


L-Theanine has been shown to decrease the negative effects of alcohol on the liver. In an animal study, it was shown that all ethanol metabolising enzymes in the liver are regulated by L-Theanine. Basically, alcohol was found to be metabolised faster and that negative effects from long-term alcohol consumption could be decreased by using L-Theanine supplements.


Derivatives (similar chemicals) of L-Theanine are being studied for their antitumor effects. At least one study has found four chemically similar molecules to L-Theanine that have significant effects in reducing movement and growth of a variety of melanoma cells.


In a type of worm, supplementation with mild to high dosages of L-Theanine appears to increase lifespan by around 3.6%, on average, and improve the maximal lifespan by up to 4.4%.[17]  

Some studies have found that L-Theanine has anticonvulsive properties at low dosages, especially against caffeine (which can sometimes increase the risk of convulsions). [18]


L-Theanine may help improve vascular blood flow through the increased production of nitric oxide enzyme (eNOS). Nitric oxide is important for regulating blood flow, and an increase in this compound may help to improve blood flow and to support and healthy circulatory system.[19]


L-theanine recommended dosage


According to Examine.com, L-Theanine is usually taken in doses of around 100-200 mg, often combined with Caffeine.[20] Many of the most recent studies on L-Theanine have used doses of 200 mg, twice daily. L-Theanine from Liftmode comes with a 0.65cc measuring scoop and is guaranteed to be at least 99% pure, with an included certificate of analysis (CoA).


Do not exceed the recommended serving size.


L-theanine side effects / warnings


WebMD lists L-theanine as possibly safe when used over short periods of time. There is not enough data on use in pregnant women to make a conclusion about safety during pregnancy. Talk to your doctor if you are pregnant or breastfeeding and would like to use L-Theanine supplements.[21]


The studies on L-Theanine for its various purposes that we examined in this article all listed L-theanine as a safe and effective supplement, often implying using this compound as a safer, more natural alternative to other, more dangerous chemicals.


If you are using any medication it is recommended that you consult your physician prior to consuming L-Theanine supplements.


High doses of L-Theanine have not been associated with negative side effects. However, it is not recommended to exceed the suggested serving size. A word of caution: Taking pure caffeine or caffeine extracts can be dangerous in high dosages and death from overdose is possible - please be careful when consuming Caffeine with L-Theanine.




[1] Blog post: “L-theanine: Why drinking green tea is relaxing”, Ricardo Caicedo, My Japanese Green Tea, available online at http://www.myjapanesegreentea.com/l-theanine [Accessed December 19, 2017]

[2] Narukawa M, Morita K, Hayashi Y. “L-theanine elicits an umami taste with inosine 5'-monophosphate.” Biosci Biotechnol Biochem. 2008 Nov;72(11):3015-7. Epub 2008 Nov 7.

[3]   “Green tea history” Revolutiontea.com, available online from http://www.revolutiontea.com/tea-articles/green-tea-history.html [Accessed December 19, 2017]

[4]L-Theanine”, Memorial Sloan Kettering Cancer Center online resources (2015), available online from https://www.mskcc.org/cancer-care/integrative-medicine/herbs/l-theanine [Accessed December 19, 2017]

[5] Lu K, et al. “The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans.”, Hum Psychopharmacol. 2004 Oct;19(7):457-65.

[6] Nobre AC, Rao A, Owen GN. “L-theanine, a natural constituent in tea, and its effect on mental state”, Asia Pac J Clin Nutr. 2008;17 Suppl 1:167-8.

[7] Pivik RT, Harman K. “A reconceptualization of EEG alpha activity as an index of arousal during sleep: all alpha activity is not equal.” J Sleep Res. 1995 Sep;4(3):131-137.

[8] Kimura K, et al. “L-Theanine reduces psychological and physiological stress responses.” Biol Psychol. 2007 Jan;74(1):39-45. Epub 2006 Aug 22.

[9] Nathan PJ, Lu K, Gray M, Oliver C .“The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent.”, J Herb Pharmacother. 2006;6(2):21-30.

[10] Giesbrecht T, et al. “The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.”, Nutr Neurosci. 2010 Dec;13(6):283-90.

[11]Distracted? Tea might help your focus” by Janet Raloff, Sept 2007, Sciencenews.org, available online at https://www.sciencenews.org/article/distracted-tea-might-help-your-focus [Accessed December 19, 2017]

[12] Giesbrecht T, et al. “The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.” Nutr Neurosci. 2010 Dec;13(6):283-90.

[13] Lyon MR, Kapoor MP, Juneja LR. “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.Altern Med Rev. 2011 Dec;16(4):348-54

[14]L-theanine and sleep quality” ISMH.org, available online from http://www.ismh.org/en/scientific-spotlight/l-theanine-and-sleep-quality/ [Accessed December 19, 2017] 

[20]Theanine”, Examine.com, available online [Accessed December 19, 2017]

[21]Theanine Uses and Risks”, WebMD.com, available online from https://www.webmd.com/vitamins-and-supplements/theanine-uses-and-risks [Accessed December 19, 2017[