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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 to have health-promoting effects.


Background of L-Theanine

Important Information, Benefits, Effects, and Important Facts 


Theanine (L-Theanine or 5-N-Ethyl-Glutamine) is an amino acid that is not required for the building of proteins and is found in a variety of plants and mushrooms. Green tea, red wine, and grapefruits are all good natural sources of dietary L-Theanine. The benefits of L-Theanine have been known for hundreds of years, as it was widely used in the East in the form of Green Tea (in combination with Caffeine).


Some of the reasons why people today use L-Theanine supplements include the benefits of being able to reduce feelings of stress and to promote wellbeing, to improve mood, to boost cognitive performance, and to improve sleep quality. Studies have found that L-Theanine helps to reduce stress and promote relaxation without the adverse effects of drowsiness. L-Theanine goes very well with Caffeine. Many people today swear by the benefits of L-Theanine supplements. Do not exceed the recommended serving size for this supplement. 


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L-Theanine Reviews



I originally found out about L-theanine from a friend. I take it primarily before bed and, for me, it really helps calm my mind in the evening so I can sleep more soundly and not wake up as often. I have a lot of trouble staying asleep. During the day it helps me not feel as stressed also. I tried many brands, but this brand has had the most consistent and best results





At a Quick Glance


Also Known As


How It Works

Blocks glutamate binding
Improves GABA activity
Boosts serotonin and dopamine
Enhances alpha-brainwaves

Is Used For

Reducing feelings of stress
Cognitive performance
Mood enhancement
Natural sleep aid

Medical Disclaimer

Not intended to treat, diagnose, or cure any disease or ailment. Please read and fully understand potential adverse effects before using this product. These statements have not been reviewed by the FDA and are not written by a medical professional. Please consult your doctor before using any supplements, especially if you have any medical conditions.





Benefits and Effects on Humans

Based on Available Scientific Research and Anecdotal Evidence



Used For: Efficacy
Reducing Stress ★★★★★
Cognitive Enhancement ★★★★
Improving Mood ★★★★
Natural sleep aid ★★★★
Neuroprotective ★★★
Synergy with caffeine ★★★★★
Supporting a healthy metabolism ★★★



How to Use

Recommended Serving Size and Application


Serving size

According to Examine.com, L-Theanine is usually taken at a serving size of around 100-200 mg, and often combined with Caffeine. Many of the most recent studies on L-Theanine have used servings of 200 mg, twice daily. Our L-Theanine capsules contain 200 mg pure L-Theanine. Powder form 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).



In capsule form: Simply swallow 1-2 capsules with a glass of water.

In powder form:

  1. ‘Solution’ method:
    1. Measure the correct serving size of L-Theanine with a measuring scoop or scale.
    2. Pour into a glass of water.
    3. Stir until fully dissolved (easier with HCl form), and swallow.
    4. If necessary, wash the glass out with more water and swallow any residual undissolved powder.



Evidence-Based Research




1. Summary


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 non-dietary 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.[2]


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 good sleep quality (so it doesn’t necessarily 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.[3]


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. 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 article:


“[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… properties.”[4]


l-theanine is great for relaxation


2. Chemical Information


Chemically, L-Theanine is the enantiomer of D-Theanine, and is a member of the glutamine derivatives class of compounds – compounds that contain glutamine or a derivative. It is an analogue of the amino acid L-Glutamine, and is ethylated on the amide nitrogen. L-Glutamine itself is a non-proteinogenic amino acid (it is not used to synthesize proteins) – and the same goes for L-Theanine. L-Theanine is water soluble and moderately acidic.[5]



3. Benefits and Effects in Humans


3.1. 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 2004 study, the effects of L-Theanine were compared to those of a commonly prescribed anxiolytic compound, in 16 volunteers. L-Theanine was found to reduce baseline stress levels by creating a calmer and relaxed feeling, while the common anxiolytic compound had no effect on baseline stress levels.[6] 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 alphabrainwaves.2 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]


3.2. Helps to Support Enhanced 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 neurochemicals are associated with improvements in mood, attention, and relaxation. In both the East and the West, it has long been known that drinking tea helps with managing stress. A number of scientific studies have backed up this claim and indicated 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, found that L-Theanine, in combination with caffeine, increased alertness and boost brain power better than either compound taken alone.10


3.3. Helps to Improve Sleep Quality

There is evidence that L-Theanine supplements can significantly improve sleep quality. In a 2011 study on children with attention-deficit/hyperactivity (ADHD) disorder, researchers found that daily supplementation of 400 mg L-Theanine significantly improved sleep quality over a six-week period.[12] 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 20 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.[13] 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.


3.4. 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 250 mg L-Theanine to 150 mg anhydrous Caffeine resulted in an improvement in reaction time and alertness with fewer complaints of caffeine-associated headaches.11


3.5. Other Health Benefits

First, 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.[14]


Second, in a type of worm, supplementation with moderate to large amounts of L-Theanine increased lifespan by around 3.6%, on average, and improved maximal lifespan by up to 4.4%.[15] This helps give credibility to the longevity-enhancing claims made about Theanine and green tea, although more studies in humans would help.

Third, studies have found that L-Theanine has anticonvulsive properties at low servings, especially against caffeine (which can sometimes increase the risk of convulsions).[16]


Finally, 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 a healthy circulatory system.[17]

l-theanine chemical structure 


4. Safety and Toxicity


4.1. Side Effects

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.[18]


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 compounds.


Large servings of L-Theanine have not been associated with serious negative side effects. However, it is not recommended to exceed the suggested serving size. Side effects of larger servings may include nausea, upset stomach, and irritability.[19]


If you are using any medication it is highly recommended that you consult your physician before using L-Theanine supplements.



About Liftmode.com


Why Buy from Us?

Our mission is to help improve the quality of your life. We develop, test and distribute science-based, top quality pure supplements and nootropics to support your body and mind. We provide independent third-party testing for all our products, which are always shipped with a Certificate of Analysis (CoA) to ensure the highest quality and purity.

We are a multi-faceted team from around the world, with expertise in a variety of areas including biochemistry, physiology, neuroscience, microbiology, as well as business and marketing. We are well-known for our great customer service and high-quality products, attested to on Trustpilot: https://www.trustpilot.com/review/liftmode.com as well as Reddit, and have an A+ score from the BBB.



How We Research Our Content

Our content is written using meticulous research methods and claims are backed by links to scientific references, wherever possible. The author and editors of Liftmode's Research Team have strong academic backgrounds in microbiology, physiology, and biochemistry.

Content Updated On: December 5th, 2018


Scientific Support and References


[1] Patel, K. (2018). Theanine. Examine.com. [online] Available at https://examine.com/supplements/theanine/

[2] Nobre, A.C., Rao, A., Owen, G.N. (2008). L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr, 17 Suppl 1:167-8.

[3] Narukawa, M., Morita, K., Hayashi, Y. (2008). L-theanine elicits an umami taste with inosine 5′-monophosphate. Biosci Biotechnol Biochem, 72(11):3015-7.

[4] L-Theanine. (2018). Memorial Sloan Kettering Cancer Center. [online]. Available at https://www.mskcc.org/cancer-care/integrative-medicine/herbs/l-theanine

[5] Theanine: Compound Summary for CID 439378. (2018). PubChem: US National Library of Medicince. [online]. Available at https://pubchem.ncbi.nlm.nih.gov/compound/L-Theanine

[6] Lu, K., Gray, M.A., Oliver, C., Liley, D.T., Harrison, B.J., Bartholomeusz, C.F., Phan, K.L., Nathan, P.J. (2004). The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans, Hum Psychopharmacol, 19(7):457-65.

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

[8] Kimura, K., Ozeki, M., Juneja, L.R., Ohira, H. (2007). L-Theanine reduces psychological and physiological stress responses. Biol Psychol, 74(1):39-45.

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

[10] Giesbrecht, T., Rycroft, J.A., Rowson, M.J., De Bruin, E.A. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness, Nutr Neurosci, 13(6):283-90.

[11] 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. Biol Psychol, 77(2):113-22.

[12] 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. Altern Med Rev, 16(4):348-54

[13] Unno, K., Noda, S., Kawasaki, Y., Yamada, H., Morita, A., Iguchi, K., Nakamura, Y. (2017). Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content. Nutrients, 19;9(7).

[14] Sadzuka, Y., Inoue, C., Hirooka, S., Sugiyama, T., Umegaki, K., Sonobe, T. (2005). Effects of theanine on alcohol metabolism and hepatic toxicity. Biol Pharm Bull, 28(9):1702-6.

[15] Zarse, K., Jabin, S., Ristow, M. (2012). L-Theanine extends lifespan of adult Caenorhabditis elegans. Eur J Nutr, 51(6):765-8.

[16] Choopankareh, S., Vafaee, F., Shafei, M.N., Sadeghnia, H.R., Salarinia, R., Zarepoor, L., Hosseini, M. (2015). Effects of melatonin and theanine administration on pentylenetetrazole-induced seizures and brain tissue oxidative damage in ovariectomized rats. Turk J Med Sci, 45(4):842-9.

[17] Siamwala, J.H., Dias, P.M., Majumder, S., Joshi, M.K., Sinkar, V.P., Banerjee, G., Chatterjee, S. (2013). L-theanine promotes nitric oxide production in endothelial cells through eNOS phosphorylation. J Nutr Biochem, 24(3):595-605.

[18] Theanine Uses and Risks. (2017). WebMD.com. [online]. Available at https://www.webmd.com/vitamins-and-supplements/theanine-uses-and-risks

[19] Mehta, F. (2017). What You Should Know About L-Theanine. Healthline.com. [online] Available at https://www.healthline.com/health/l-theanine#risks-and-side-effects