It’s one of the world’s most often-consumed and popular beverages, along with water and coffee. Not only does it contain the stimulant alkaloid, caffeine, that a lot of us love—but this beverage is also chock-full of health-boosting benefits.

We’re talking about the world-renowned beverage, green tea.

Though it contains caffeine and is imbibed in the same way as coffee (to get an energy boost), there’s actually a lot more to green tea than meets the eye. For one, there are green tea’s antioxidants, such as catechins and polyphenols, which can help stave off chronic inflammation, degeneration, and more.

But it may surprise some people that the green tea plant (Camellia sinensis) contains amino acids that are very beneficial to health.

The most studied and well-known of these: l-theanine.


As a separate entity and healthful compound all its own, l-theanine is quite impressive, even when compared to the majority of green tea’s other well-researched health compounds.

It could even be said that this humble amino acid may be the healthiest thing about green tea overall.

L-theanine isn’t just found in green tea, however. It’s also found in other kinds of tea made from the same plant, such as black tea, white tea, and oolong tea, too.

Beyond this group of plant sources though, finding sources of l-theanine—such as from the diet—are scarce. Besides teas made from Camellia plants, only a single wild edible mushroom is known to contain any significant amounts.

Fortunately, finding supplements of the compound isn’t difficult.


L-theanine can, of course, be enjoyed in a piping hot cup of green tea. But one of the best ways to experience it: extracted separately and in high amounts in an easy-to-take, highly concentrated supplement or powder formula.

Concentrated l-theanine is most likely to bring the very best health benefits and in the fastest and most noticeable way possible.

Long ago in China, green tea leaves were chewed or brewed as a daily renewing tonic for health. Its benefits were so remarkable, its consumption—along with the l-theanine within it— became practically ingrained into everyday life.

So what can be expected from this mighty amino acid? According to both traditional ancient use and modern scientific research, quite a bit.


It’s not just catechins and polyphenols that make green tea famous for antioxidant action.

L-theanine appears to hold up its own corner, too, and can be added to the long lineup of antioxidants that make green tea a rich treasure trove for health.

What this means: l-theanine can scavenge free radicals in the body that contribute to organ or tissue breakdown, inflammation, degeneration, and even help reduce the effects of aging. No doubt, its antioxidant traits are the reason for its daily consumption for helping extend longevity in ancient China.

There’s no shortage of studies to support this, too. In one study, l-theanine had strong enough antioxidant action to even protect against liver damage. In another, it was shown to be powerful enough to heal ulcers.


Anxiety can be one of the most difficult emotions and mental states we struggle with.

For some of us, it’s just a passing feeling. For others among us, anxiety is a very real and very difficult mood disorder that comes and go as it pleases.

In any realm of anxiety, l-theanine could be of surprising help and support.

One study showed that l-theanine supplementation actually suppressed feelings of anxiety in a large number of human subjects. Even more interestingly, another study in 2011 demonstrated that anxiety could be helped with the amino acid in test subjects with schizophrenia.

This may seem counterintuitive that such a high-caffeine tea could reduce anxiety, when caffeine is known to typically give one the jitters.


Which brings us seamlessly into our next health benefit of l-theanine:

Even though l-theanine and caffeine are found in great amounts in the same plant, l-theanine appears to keep the negative effects of caffeine at bay, while only supporting the good stuff.

A recent 2015 study even proved this, showing that l-theanine and caffeine taken together reduce high blood pressure and nervousness compared to caffeine taken alone.

This may help explain why green tea, even though it has much higher levels of caffeine than coffee, gives people a much smoother ride to an alertness boost than coffee does.

As such, when l-theanine is taken together with caffeine, one can experience a stimulated, energy-boosting effect without the unwanted anxiety and jumpiness.


This botanically-sourced compound can gently pull away anxiety and stimulate energy in a calming, not-so-over-the-top way. Naturally, this can also bring better brain function and focus to the forefront.

In fact, a 2011 study showed that l-theanine indeed has benefits for the brain and mind.

In this double-blind, placebo-controlled trial, an l-theanine extract (along with green tea extract) helped improve cognitive impairment in test subjects who experience problems with cognition on the regular, or who have cognitive disorders.

More notably, issues with memory and attention were observed to improve.

Though more research is needed, this could possibly make l-theanine one day a natural therapy for neurological disorders such as Alzhiemer’s disease or Parkinson’s. It could also help improve brain fog, too.


Issues with the brain like anxiety are one thing. Mood disorders like stress and depression are a whole other ballgame—yet are just as challenging.

But much like anxiety and other mental state-related issues, l-theanine has a scientifically-proven way of going beyond lifting one’s spirits to help depression.

One study in 2017 showed that long-term use of the amino acid in depressed human subjects could help with a wide range of symptoms related to depression, as well as help with depression itself.

In addition, depressed and stressed animal subjects were shown to benefit from l-theanine in another study.

A natural anti-depressant? Maybe.

It’s still too early to tell if l-theanine could be called such by research, though studies thus far are promising.


An antioxidant compound that helps strengthen the mind and brain—but what about the heart?

As all good antioxidants tend to do, even a powerful one like l-theanine brings perks to the cardiovascular system.

No doubt, part of how it accomplishes this is by curbing inflammation from free radicals, which up one’s chances of heart disease and spiking high blood pressure.

One fascinating study also showed that l-theanine helped boost nitric oxide in the blood, which in turn dilates blood vessels to help lower blood pressure. This, in turn, can lower heart disease risk.

Even a review on the tea plant mentioned that there are many studies showing quantifiable properties in the way green tea and its compounds improve heart health.


Another benefit antioxidants are widely known for: they can help enhance immunity.

Since antioxidants block harmful inflammation in how they interact with free radicals, this has a way of freeing the body’s immune system to deal with bigger, better problems than chronic inflammation, such as illnesses and autoimmunity.

Studies on l-theanine suggest this is true, too. This includes a study where l-theanine strengthened immunity and also balanced it, reducing inflammatory proteins associated with a troubled immune system.

Such powerful benefits could be useful in many ways. Not only could it help people with immune-related issues like rheumatoid arthritis, but it could also be used as a way to keep the immune system strong against very common illnesses like colds and flu.


If there’s anything that could be called the strongest foundation for health, getting high quality, restorative sleep would probably be it. Even better, l-theanine could be a great ally in this regard, too.

In close concert with its anti-anxiety, anti-stress, and anti-depression properties, l-theanine can offer powerful support for better sleep.

Stress, anxiety, and depression are all mental states and moods that can keep us from sleeping well. And if l-theanine can help these, it can surely aid in the sleep department.

Best of all, research is showing this could certainly be the case. One study revealed that l-theanine could even help highly caffeinated subjects experience better sleep. Another study even showed that it helped subjects with ADHD get better sleep, too.


A botanically-based supplement that could help with improved metabolism and weight loss? Apparently so.

Green tea and l-theanine are common ingredients in weight loss supplements and combination botanical formulas.

Unlike “magical weight loss” products that promise they will “burn fat like crazy,” l-theanine doesn’t work that way. Instead, studies show long-term use of the amino acid could support metabolism, thereby enhancing healthy weight management.

Some research shows that it has an anti-obesity effect and can even help test subjects drop body weight, though more updated studies are needed.

Still, science today is turning up generally positive outlooks for green tea in general and weight loss, such as this study showing that green tea combats obesity by bolstering gut health.


Because l-theanine is shown to be such a strong antioxidant, this means that it may be one of the most potent nutrients to help shield against the vast majority of chronic and degenerative diseases.

This, in fact, includes one of the most-dreaded and deadliest chronic diseases of all: cancer.

As a rule, antioxidants keep out free radicals from having their way with the body and its systems. As it so happens, free radicals can be one of the many ways cancer cells develop, grow, and proliferate.

Studies suggest, however, that l-theanine can particularly target cancerous cells. In one particular study, the compound was shown inhibiting the growth of cancer cells in the lungs, in a way helping literally fight lung cancer.


Enraptured by what l-theanine could offer in the world of health? Look no further.

We include l-theanine in one of our popular herbal supplement formulas, Tranquil Mind. The science supporting its possible benefits to anxiety, stress, and depression simply cannot be overlooked!

Tranquil Mind Also Includes:

  • L-Tryptophan – Another nerve-calming amino acid that helps the body produce more serotonin, which helps stress
  • Ashwagandha – Supports hormonal balance to lower stress
  • Griffonia simplicifolia – Rich in natural levels of 5-HTP to fight anxiety and help increase serotonin
  • Jiaogulan (Gynostemma) – The ultimate adaptogen for lowering stress
  • Passionflower – Shown to help improve sleep, combat anxiety, and help with depression
  • Schisandra – Another powerful adaptogen known to help shield the body against effects of stress and anxiety

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Guilan Li, Yin Ye, Jingjing Kang, Xiangyang Yao, Yizhou Zhang, Wei Jiang, Min Gao, Yudong Dai, Yinqiang Xin, Qi Wang, Zhimin Yin, Lan Luo (2012). L-Theanine prevents alcoholic liver injury through enhancing the antioxidant capability of hepatocytes. Food and Chemical Toxicology 50(2) 363-372. Retrieved from
Sirshendu Chatteree, Ananya Chatterjee, Surmi Roy, Biswajit Bera, Sandip K. Bandyopadhyay (2014). L-Theanine healed NSAID-induced gastric ulcer by modulating pro/antioxidant balance in gastric ulcer margin. Journal of Natural Medicines 68(4) 699-708. Retrieved from
Keiko Unno, Naoki Tanida, Naoto Ishii, Hiroyuki Yamamoto, Kazuaki Iguchi, Minoru Hoshino, Atsushi Takeda, Hayato Ozawa, Tsutomu Ohkubo, Lekh Raj Juneja, Hiroshi Yamada (2013). Anti-stress effect of theanine on students during pharmacy practice: Positive correlation among salivary a-amylase activity, trait anxiety and subjective stress. Pharmacology Biochemistry and Behavior Vol. 111 pp. 128-135. Retrieved from
Michael S. Ritsner, Chanoch Miodownik, Yael Ratner, Tatyana Shleifer, Maria Mar, Leonid Pintov, Vladimir Lerner (2011). L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients With Schizophrenia and Schizoaffective Disorder: An 8-Week, Randomized, Double-Blind, Placebo-Controlled, 2-Center Study. Journal of Clinical Psychiatry. Retrieved from
F.L. Dodd, D.O. Kennedy, L.M. Riby, C.F. Haskell-Ramsay (2015). 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. Psychopharmacology 232(14) 2563-2576. Retrieved from
Sang-Ki Park, In-Chul Jung, Won Kyung Lee, Young Sun Lee, Hyoung Kook Park, Hyo Jin Go, Kiseong Kim, Nam Kyoo Lim, Jin Tae Hong, Sun Yung Ly, Seok Seon Rho (2011). A Combination of Green Tea Extract and L-Theanine Improves Memory and Attention in Subjects with Mild Cognitive Impairment: A Double-Blind Placebo-Controlled Study. Journal of Medicinal Food 14(4). Retrieved from
Shinsuke Hidese, Miho Ota, Chisato Wakabayashi, Takamasa Noda, Hayato Ozawa, Tsutomu Okubo, Hiroshi Kunugi (2017). Effects of chronic L-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatrica 29(2) 72-79. Retrieved from
Cui Yin, Lingshan Gou, Yi Liu, Xiaoxing Yin, Ling Zhang, Genguang Jia, Xuemei Zhuang (2011). Antidepressant-like Effects of L-theanine in the Forced Swim and Tail Suspension Tests in Mice. Phytotherapy Research 25(11) 1636-1639. Retrieved from
Jamila H. Siamwala, Paul M. Dias, Syamantak Majumder, Manoj K. Joshi, Vilas P. Sinkar, Gautam Banerjee, Suvro Chatterjee (2013). L-Theanine promotes nitric oxide production in endothelial cells through eNOS phosphorylation. The Journal of Nutritional Biochemistry 24(3) 595-605. Retrieved from
Davide Grassi, Giovambattista Desideri, Paolo Di Giosia, Martina De Feo, Emanuela Fellini, Paola Cheli, Livia Ferri, Claudio Ferri (2013). Tea, flavonoids, and cardiovascular health: endothelial protection. The American Journal of Clinical Nutrition 98(6) 1660S-1666S. Retrieved from
Chengjian Li, Haiou Tong, Qiongxian Yan, Shaoxun Tang, Xuefeng Han, Wenjun Xiao, Zhilang Tan (2016). L-Theanine Improves Immunity by Altering TH2/TH1 Cytokine Balance, Brain Neurotransmitters, and Expression of Phospholipase C in Rat Hearts. Medical Science Monitor 22: 662-669. Retrieved from
Hwan-Soo Jang, Ji Young Jung, Il-Sung Jang, Kwang-Ho Jang, Sang-Hyun Kim, Jeoung-Hee Ha, Kyoungho Suk, Maan-Gee Lee (2012). L-theanine partially counteracts caffeine-induced sleep disturbances in rats. Pharmacology Biochemistry and Behavior 101(2) 217-221. Retrieved from
Michael R. Lyon, Mahendra P. Kapoor, Lekh R. Juneja (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) 348-354. Retrieved from
  1. Zheng, K. Sayama, T. Okubo, L.R. Juneja, I. Oguni (2004). Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice. In Vivo 18(1) 55-62. Retrieved from
Zhibin Liu, Zhichao Chen, Hongwen Guo, Dongping He, Huiru Zhao, Zhiyao Wang, Wen Zhang, Lan Liao, Chen Zhang, Li Ni (2016). The modulatory effect of infusions of green tea, oolong tea, and black tea on gut microbiota in high-fat-induced obese mice. Food & Function Issue 7(12) 4869-4879. Retrieved from!divAbstract
Guoying Zhang, Xinshan Ye, Dexin Ji, Huarong Zhang, Fujia Sun, Chungqing Shang, Ying Zhang, Erxi Wu, Fengfei Wang, Fei Wu, Huihui Tian, Xin Liu, Linlin Chen, Kun Liu, Yishan Wang, Hanchen Liu, Wenhua Zhang, Yukun Guan, Qinwen Wang, Xiaohang Zhao, Xiaochun Wan (2014). Inhibition of lung tumor growth by targeting EGFR/VEGFR-Akt/NF-kB pathways with novel theanine derivatives. Oncotarget 5(18) 8528-8543. Retrieved from