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Introduction                                    L-Theanine for Relaxation & Stress (pdf file)

First introduced centuries ago in Southeast Asia, tea has become the most widely consumed beverage worldwide aside from water and it is now cultivated in more than 30 different countries. Extensive research has been conducted on tea, specifically green tea, for its many medicinal properties.

It has been estimated that nearly 65 percent of the adult population has experienced some form of stress or anxiety, and these numbers are on a continual rise due to the busy lifestyles we have adopted. Confronted daily with the stresses of our lives, our jobs, our families, etc., we continue to search for ways to relax and reduce our stress levels. In 1998, pharmaceutical sales of anti-depressants totaled $4.79 billion dollars while sales of anxiety drugs totaled $722 million1.

Recently, much attention has been focused on L-Theanine, a unique amino acid commonly found in green tea. It has been determined that L-Theanine is a derivative of Glutamic Acid which is one of the neurotransmitters found in the brain.

Absorbed in the intestinal brush-border membrane, L-Theanine, due to its fat solubility, is incorporated into the brain via the leucine-preferring transport system of the blood brain barrier. Once absorbed into the brain, L-Theanine exhibits many positive, physiological effects.

In an experiment conducted by Hihehiko Yokogoshi, PhD and Takehiko Terashima, PhD at the Laboratory of Nutritional Biochemistry in Shizuoka, Japan, it was determined that dopamine concentrations in the brain, especially in the striatum, hypothalamus, and hippocampus increased significantly after the administration of L-Theanine. Dopamine, one of the brain’s neurotransmitters, is said to affect human emotion. L-Theanine also increases GABA levels in the brain which leads to a feeling of well-being.

The brain transmits four different categories of brain waves which are determined by frequency: Gamma (g), Theta (q), Alpha (a), and Beta (b). Gamma waves are present during sound sleep and Theta waves indicate dozing or sleeping. While Beta waves are present during an awake, excited state, Alpha waves signify an awake, relaxed state. Because L-Theanine promotes Alpha wave generation in the brain, an awake, alert and relaxed physical and mental condition is achieved which demonstrates Theanine’s effectiveness in stress management.

Unlike Kava Kava, Valerian, and St. John’s Wort, L-Theanine does not cause drowsiness or impair a person’s motor skills. Effects of L-Theanine are experienced within 30 minutes of consumption and no drug interactions are known.

L-Theanine has been shown to work antagonistically against the negative side effects of caffeine. After injecting mice with Theanine intraperitoneally or subcutaneously, Kimura and Murata reported that Theanine effectively decreased convulsions induced by high doses of caffeine and the spontaneous motor activity produced by lower caffeine doses. L-Theanine has also been found effective in reducing the hypertension and disturbance of sleep often associated with the use of caffeine.

It is conceived that a large percentage of deaths are caused by atherosclerosis, a cardiovascular disorder characterized by a thickening of the arteries. Recent studies suggest that the oxidation of low-density lipoprotein (LDL) may be responsible for causing atherosclerosis. It has been reported that Theanine may reduce plasma total cholesterol, cholesterol ester and very-low-density lipoprotein cholesterol.

It has also been known that blood pressure is regulated by catecholaminergic and serotonergic neurons in the brain and the peripheral nervous system. Spontaneously hypertensive rats experienced a significant reduction in blood pressure after being administered high doses of Theanine.

Theanine was approved in 1964 by the Japanese Ministry of Health and Welfare for use in food and is currently available in more than 50 food products including ice cream, candy, beverages and supplements.

Perhaps one of the most extensively researched and documented nutritional ingredients, Theanine has demonstrated safety and efficacy in many applications such as:

v Promoting relaxation without causing drowsiness

v Improving learning and concentration

v Heightening mental acuity

v Supporting the Immune System

v Lowering Cholesterol

v Reducing stress and anxiety

v Reducing the negative side effects of caffeine


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2000. Suntheanine® Relaxing, health promoting amino acid found in tea. Taiyo Kagaku. 
Juneja L, et al. 1999. L-Theanine – a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology. 10: 199-204. 
Yokozawa T, et al. 1997. Influence of green tea and its three major components upon low density lipoprotein oxidation. Exp Toxic Pathol 49: 329-335. 
Yokogoshi H, et al. 1998. Effect of Theanine, r-Glutamylethylamide, on Brain Monoamines and Striatal Dopamin Release in Conscious Rats. Neurochemical Research. 23: 667-673. 
Graham, Harnold N. 1992. Green Tea Composition, Consumption, and Polyphenol Chemistry. Preventative Medicine. 21: 334-350. 
Sagesaka Y, et al. Pharmacological Effect of Theanine. Ito-en Central Research Institute. 362-365. 
Kobayashi K, et al. 1998. Effects of L-Theanine on the Release of (-Brain Waves in Human Volunteers. Nippon Noegikagaku Kaishi. 72: 153-151. 


Approved Structure/Function Claims for Suntheanine®:

Federal Register – January 6, 2000 (page 1000 to 1050)
Food and Drug Administration Final Rule under Food Labeling – 21 CFR Part 101.93
Statements Made for Dietary Supplements Concerning the Effect of the Product on the Structure or Function of the Body

Acceptable structure/function claims for relaxation: 

All of the following are acceptable structure/function claims for relaxation, as all suggest occasional rather than long-term or chronic mood changes. Although occasional or acute symptoms can be characteristic of diseases in other settings, none of the occasional symptoms referred to here is characteristic of a specific disease: 

Promotes relaxation 
Helps promote relaxation 
Promotes relaxation without drowsiness 
Helps promote a restful, relaxed state 
Promotes a sense of relaxation 
Promotes a relaxed feeling 
Reduces stress 
Helps to reduce stress 
Eases occasional simple nervous tension 
Eases nervousness due to common everyday overwork and fatigue 
Calming down and relaxing 
Gently soothe away the tension 
Calmative 
Resolving that irritability that ruins your day 
Reduces restlessness 
Reduces nervous irritability 
When you’re under occasional stress, helps you work relaxed 
Acceptable structure/function claims for sleep aids: 

For the relief of occasional sleeplessness (not a characteristic symptom of a disease) 
Acceptable structure/function claims for alertness aids: 

Helps restore mental alertness or wakefulness when experiencing fatigue or drowsiness (should not imply treatment of chronic fatigue or daytime drowsiness as these are symptoms of chronic fatigue syndrome and narcolepsy, respectively). 
Acceptable structure/function claims for PMS: 

Supports a normal, healthy attitude during PMS (PMS is generally a common, mild condition associated with a normal physiologic process). 
Diminishes normal symptoms of premenstrual syndrome 

L-Theanine Research

Complete copies of the following scientific and dietary research available upon request from NutriScience Innovations, LLC.

Sugiyama T. Sadzuka Y. Tanaka K. Sonobe T.
Inhibition of glutamate transporter by theanine enhances the therapeutic efficacy of doxorubicin.
Toxicol Lett 2001 Apr 30;121(2):89-96

Kakuda, T. et al.
Neuroprotection of gamma-glutamylethylamide (theanine) in middle cerebral artery occlusion in the rat. Society for Neuroscience Abstracts. Vol. 26, No. 1-2, 2000 pp 183.19.

Sadzuka Y., Sugiyama T., Sonobe T.
Improvement of idarubicin induced antitumor activity and bone marrow suppression by theanine, a component of tea. Cancer Lett 2000 Oct 1;158(2):119-124

Kakuda, T. et al.
Protective effect of gamma-glutamylethylamide (theanine) on ischemic delayed neuronal death in gerbils. Neuroscience Letters. Vol.289, No. 3, August 11, 2000. Pp 189-192

Yokogoshi H, et al.
Effect of Theanine, r-glutamylethylamide, on Brain Monoamines, striatal dopamine release and some kinds of behavior in rats. Nutrition 2000, Sep; 16(9):776-777

Kakuda, T. et al.
Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat.
Biosci Biotechnol Biochem 2000 Feb;64(2):287-93

Sugiyama T. et al.
Liver injury-preventative effect of tea theanine in rats.
Journal of Food Science. Jan.-Feb. 2000. Vol.65, No. 1, p. 30-33

Sadzuka Y. et al.
Efficacies of tea components on doxorubicin induced antitumor activity and reversal of multi-drug resistance. Toxical Lett. 2000 Apr 3;114(1-3):155-62

Sugiyama T. et al.
Theanine, a major amino acid of green tea, enhances anitumor activity of doxorubicin via inhibition of glutamate transsporter. Proceedings of the Association for Research Annual. March 2000. No 41, p. 242

Juneja L, et al.
L-theanine - A unique amino acid of green tea and its relaxation effect in humans.
Trends in food science technology June/July 1999. v. 10(6/7) p. 199-204

Sugiyama T.
Membrane transport and antitumor activity of pirarubicin, and comparison with those of doxorubicin. Jpn J Cancer Res. 1999 Jul;90(7):775-80.

Bukowski JF, et al.
Human gamma delta T cells recognize alkylamines derived from microbes, edible plants, and tea: implications for innate immunity. Immunity. 1999 Jul;11(1):57-65.

Unno T, et al.
Protective effect of theanine, on ischemic neuronal death in transient forebrain ischemia model. Society for Neuroscience Abstracts. 1999, Vol. 25, No. 1-2, p. 575.

Unno T, et al.
Metabolism of theanine, small gamma-glutamylethylamide, in rats.
Journal of Agricultural and Food Chemistry. April 1999, Vol. 47, No. 4 p. 1593-1596.

Sugiyama T, et al.
Theanine, a major amino acid in green tea, inhibits severe leukopenia and enhances antitumor activity induced by idarubicin. Proc. American Assoc. Cancer Research. 40. March 1999

Terashima T, et al.
Time-dependent changes of amino acids in the serum, liver, brain and urine of rats administered with theanine. Biosci Biotechnol Biochem. 1999 Apr;63(4):615-618.

Sugiyama T, et al.
Combination of theanine with doxorubicin inhibits hepatic metastasis of M5076 ovarian sarcoma. Clin Cancer Res. 1999 Feb;5(2):413-6.

Sugiyama T, et al.
Enhancing effects of green tea components on the antitumor activity of adriamycin against M5076 ovarian sarcoma. Cancer Lett. 1998 Nov 13;133(1):19-26

Sugiyama T, et al.
Green tea component, theanine enhances the antitumor activity of adriamycin against sensitive P388 leukemia and resistant P388-ADR. Proceedings of the American Association for Cancer Research Annual Meeting. 1998, Vol. 39, p. 528.

Yokogoshi H, et al.
Theanine-induced reduction of brain serotonin concentration in rats.
Biosci Biotechnol Biochem. 1998 Apr;62(4):816-7.

Kobayashi A, et al.
Effects of L-theanine on the release of a-waves in human volunteers.
Nippon Nogeikagaku Kaishi. 1998 Vol. 72, 153-157.

Nozawa, A. et al.
Theanine, a major flavorous amino acid in green tea leaves, inhibits glutamate-induced neurotoxicity on cultured rat cerebral corticalneurons. Society for Neuroscience Abstracts. 1998, Vol. 24, No. 1-2, p. 978.

Saduka Y, et al.
Modulation of cancer chemotherapy by green tea.
Clin Cancer Res. 1998 Jan;4(1):153-6

Yokogoshi H, et al.
Effect of theanine, r-glutamylethylamide, on brain monamines and striatal dopamine release in conscious rats. Neurochem Res. 1998 May;23(5):667-73.

Yokogoshi H, et al.
Hypotensive effect of gamma-glutamylethylamide in spontaneously hypertensive rats.
Life Sci. 1998;62(12):1065-8

Yokozawa T, et al.
Influence of green tea and its three major components upon low-density lipoprotein oxidation.
Exo, Toxicol Pathol. 1997 Dec;49(5):329-35.

Yokozawa T, et al.
Inhibitory effect of green tea on injury to a cultured renal epithelial cell line, LLC-PK1.
Biosci Biotechnol Biochem. 1997 Jan;61(1):204-6

Yagyu T, et al.
Chewing-gum flavor affects measures of global complexity of multichannel EEG.
Neuropsychobiology. 1997;35(1):46-50

Kitaoka S, et al.
Transmural potential changes associated with the in vitro absorption of theanine in the guinea pig intestine. Biosci Biotechnol Biochem. 1996 Nov;60(11):1768-71.

Sadzuka Y, et al.
The effects of theanine, as a novel biochemical modulator, on the antitumor activity of adriamycin.
Cancer Lett. 1996 Aug 2;105(2):203-9.

Yokozawa T, et al.
Effects of a component of green tea on the proliferation of vascular smooth muscle cells.
Biosci Biotechnol Biochem. 1995 Nov;59(11):2134-6.

Yokogoshi H, et al.
Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneoulsy hypertensive rats. Biosci Biotechnol Biochem. 1995 Apr;59(4):615-8

Nozawa, A. et al.
Theanine a glutamate analog, stimulates NMDA-receptors by suppresses excitatory effect of caffeine in cortical neurons. Society for Neuroscience Abstracts. 1995, Vol. 21, No. 1-3, p. 835.

Graham HN.
Green tea composition, consumption, and polyphenol chemistry.
Prev Med. 1992 May;21(3):334-50.

Sagesaka Y, et al.
Pharmacological effect of theanine.
Proceedings of the International Symposium on Tea Science, August 26-29, 1991, 362-364.

Tsushida, T.
Metabolism of L-theanine in tea leaves.
JARQ (Japan Agricultural Research Quarterly.) 1987, Vol. 21, No. 1 p.42-46.

Feldheim, W. et al.
Investigation of the presence and significance of theanine in the tea plant.
Journal of the Science of Food and Agriculture. 1986, Vol. 37, No 6, p. 527-534

Kimura R, et al.
Effect of theanine on norepinephrine and serotonin levels in rat brain.
Chem Pharm Bull (Tokyo). 1986 Jul;34(7):3053-7.

Neumann, K.
Quantitive determination of theanine in tea extracts.
Deutsche Lebensmittel-Rundschau. 1982 May. v. 78(5) p. 172-174.

Oda Y, et al.
Synthesis and antibacterial activities of theanine-containing oligopeptides..
Chem Pharm Bull (Tokyo). 1980 Dec;28(12):3549-54.

Kimura R, et al.
Influence of alkylamides of glutamic acid and related compounds on the central nervous system. IV. Effect of theanine on adenosine 3’, 5’-monophosphate formation in rat cerebral cortex. Chem Pharm Bull (Tokyo). 1980 Feb; 28(2):664-6.

Shinozaki H, et al.
Theanine as a glutamic antagonist at a crayfish neuromuscular junction.
Brain Res. 1978 Jul 28;151(1):215-9.

Kimura R, et al.
Influence of alkylamides of glutamic acid and related compounds on the central nervous system. III. Effect of theanine on spontaneous activity of mice. Yakugaku Zasshi. 1975 Jul; 95(7):892-5. Japanese.

Kimura R, et al.
Influence of alkylamides of glutamic acid and related compounds on the central nervous system. II. Synthesis of Amides of Glutamic Acid and Related Compounds, and their Effects on the Central Nervous System. Chem Pharm Bull (Tokyo). 1971 Vol. 19 No. 7, 1301-1307.

Kimura R, et al.
Influence of alkylamides of glutamic acid and related compounds on the central nervous system. I. Central depressant effect of theanine. Chem Pharm Bull (Tokyo). 1971 Jun;19(6):1257-61.