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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:  Delta (Δ), Theta (θ), Alpha (α), and Beta (β). Delta 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.


Awarded “Best New Product of 2000” at Nutracon, 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.


LD50, a classification of acute ingestion toxicity, determined Theanine to be greater than 5,000 mg/Kg, causing no “significant or unreasonable risk of illness or injury”.


It has been determined that no degradation resulted when beverages containing Theanine were heated at 121( C for five minutes. Theanine is also stable in solutions ranging from 3.0 to 6.6 on the pH scale.


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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  1. 2000.  Suntheanine® Relaxing, health promoting amino acid found in tea.  Taiyo Kagaku.
  2. 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.
  3. 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.
  4. 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.
  5. Graham, Harnold N.  1992.  Green Tea Composition, Consumption, and Polyphenol Chemistry.  Preventative Medicine.  21: 334-350.
  6. Sagesaka Y, et al.  Pharmacological Effect of Theanine.  Ito-en Central Research Institute.  362-365.
  7. Kobayashi K, et al.  1998.  Effects of L-Theanine on the Release of (-Brain Waves in Human Volunteers.  Nippon Noegikagaku Kaishi.  72: 153-151.


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For further information and detailed scientific studies about L-Theanine, please contact:


Ms. Julie Thibeau, NutriScience Innovations, LLC., Fairfield, CT

Tel: (203) 334-3535 Fax: (203) 366-1850

Email:  sales@nutriscienceusa.com



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tea leaf
tea leaf