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Natural L-theanine

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Theanine is a fast-acting, non-sedative, natural relaxation supplement that reduces the impact of excitatory pathways in the brain. Each capsule contains the same amount of ltheanine found in 15-20 cups of green tea. L theanine benefits relaxation without sedation. 

L theanine supplements are ideal for;

  • Anybody looking to unwind.
  • Anybody looking to relax but maintain performance and clarity.
  • Acute stressors such as public speaking or travelling.

Most l-theanine found in food supplements is synthetic (e.g. Suntheanine) and it’s produced as a racemic using ethylamine and l-glutamine and a multi-stage synthesis. Our l theanine capsules contain 250mg natural theanine extracted from green tea from the mountainous region of Hunan Province in South Central China. We keep it as pure as possible so you won’t find additives such as lemon balm whose mechanism of action, ability to enter the brain or synergistic benefit is unknown.  

how it works;

Human studies show that theanine stimulates increases in Alpha brain waves which are indicative of a relaxed but alert mental state [12]. The type of brain wave activity is often referred to as wakeful relaxation [20] exhibiting increased creativity and increased performance under stress as well as decreased anxiety [14].

  • It is absorbed into the bloodstream and enters the brain through the leucine-preferring amino acid transporter system [11].

  • Its relaxation effect leads to increased GABA concentrations which result in general feelings of calm and wellbeing [6]. Unlike other conventional calming treatments, l theanine side effects do not include increased drowsiness, slowed reflexes or impaired concentration [15].


1. Why do you isolate theanine from green tea?

Theanine is the major amino acid in green tea and constitutes 1-2% of the dry weight of the leaves. To obtain sufficient levels of theanine for a therapeutic dose from whole green tea powder would also result in high levels of caffeine which can produce laxative effects, tannins which can cause stomach irritation & nausea on an empty stomach, and increased amounts of certain antioxidants that can hinder iron absorption.

A 2017 review of studies notes that high levels of simple green tea extract have been associated with liver damage, jaundice, acute-hepatitis like injuries and even liver failure from catechins within green tea. [4]

2. What should I notice?
Relaxation without sedation.

Oral administration of 200mg of theanine in men aged 20-25 years old also resulted in a reduction in the heart rate. [17]

3. How long does it take to have an effect?

In human studies, increased alpha waves were generated 15 minutes after oral administration [12] and it has been shown to influence the secretion and function of neurotransmitters 30 minutes after ingestion [11]. Theertham et al suggest maximum uptake in the brain is usually within 30-40 minutes. [19]

4. How do I take it?

1 l theanine capsule with a glass of water. Max 2 per day.

5. Does it help with cognition?

In human studies, theanine alone has shown virtually no positive effects on performance. However, 250mg of theanine has been found to positively interact with caffeine to enhance reaction time, the accuracy of rapid information processing, mental fatigue and tiredness. [21] This combination also enhanced the speed of rapid information processing, sentence verification and word recognition reaction time when caffeine alone did not. [13]

6.Will it make me sleepy?

No. It does not promote the onset of melatonin and it is not a sedative. Sleep inducers and sedatives normally induce drowsiness or sleep within an hour [18] whereas theanine, which achieves its maximum uptake in the brain within 30–40 minutes does not induce any sleep or drowsiness in the subjects [19].

7.Are there any side effects or contraindications?

Anybody taking medication for high blood pressure should consult their GP. If you have low blood pressure, discuss theanine with your healthcare provider before starting it.


theanine 99%, vegetable cellulose capsule, bulking agent; rice bran flour


[1] Anna C Nobre et al L-theanine, a natural constituent in tea, and its effect on mental state Asia Pacific Journal Clinical Nutrition, 2008. - Vol. 17. - pp. 167-168.

[2] Eschenauer et al Pharmacology and therapeutic uses of theanine American Journal Health-System Pharmacy,2006. - pp. 26–30.

[3] Haskell et al Cognitive and mood effects of caffeine and theanine alone Journal of Behavioural Pharmacology, 2008. - 2 : Vol. 77. - pp. 113-122.

[4] Higashiyama et al Effects of L-theanine on attention and reaction time response Journal of Functional Foods, 2011. - Vol. 3. - pp. 171-178.

[5] Juneja et al Effects of L-theanine on the release of alpha brain waves in human volunteers Trends in Food Science & Tech, 1999. - Vol. 10. - pp. 199-204.

[6] Juneja et al L-theanine - a unique amino acid of green tea and its relaxation effects in humans Trends in Food Science & Technology, 1999. - Vol. 10. - pp. 199-204.

[7] Kakuda et al Inhibiting effects of theanine on caffeine stimulation evaluated by EEG : Bioscience Biotechnology and Biochemistry , 2000. - Vol. 64. - pp. 287–293.

[8] Kakuda et al Neuroprotective effects of the green tea components theanine and catechins [Journal]. - [s.l.] : Biological and Pharmaceutical Bulletin, 2002. - Vol. 25. - pp. 1513-1518.

[9] Kenta Kimura et al L-Theanine reduces psychological and physiological stress responses Journal of Biological Psychology, 2007. - Vol. 74. - pp. 39-45.

[10] Lovallo et al Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women Journal of Pharmacology Biochemistry and Behavior. - 2006. - pp. 441–447.

[11] Lu et al The acute effects of L-theanine in comparison with alprazlam on anticipatory anxiety in humans [Journal]. - [s.l.] : Human Psychopharmacology, 2004. - Vol. 19. - pp. 457–465.

[12] Micallef et al A double blind parallel group placebo controlled comparison of sedative and amnesic effects of etifoxine and lorazpam in healthy subjects Journal of Fundamental Clinical Pharmacology, 2001. - pp. 209–216.

[13] Navarro et al Liver injury from herbal and dietary supplements Iournal of Hepatology, 2017. - 1 : Vol. 65.

[14] Ozeki et al A study of L-theanine and daytime drowsiness Japanese Journal of Physiological Anthropology, 2008. - Vol. 13. - pp. 9-15.

[15] Song et al Effects of theanine on the release of brain alpha wave in adult males Korean Journal of Nutrition, 2003. - Vol. 36. - pp. 919–923.

[16] Terashima et al Time-dependent changes of amino acids in the serum, liver, brain and urine of rats administered with theanine Journal of Bioscience, Biotechnology, and Biochemistry, 1999. - Vol. 63. - pp. 615-618.

[17] Theertham et al In Search of a Safe Natural Sleep Aid Journal of the American College of Nutrition, 2015. - 5 : Vol. 34. - pp. 436-447.

[18] Unno et al Metabolism of theanine, gamma-glutamylethylamide, in rats Journal of Agriculture & Food Chemistry, 1999. - Vol. 47. - pp. 1593-1596.

[19] Yokogoshi et al Effect of theanine, r-glutamyethylamide, on brain monoamines and striatal dopamine release in conscious rats Journal Neurochemical Research, 1998. - Vol. 23. - pp. 667–673.

[20] Bryan Janet Psychological effects of dietary components of tea: caffeine and L-theanine Journal of Nutrition Reviews, 2008. - 2 : Vol. 66. - pp. 82-90.

[21] Toxicology Department of Pharmacology and A 13-week dietary toxicity and toxicokinetic study with theanine in rats Medical College of Virginia, Virginia
Commonwealth University.

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