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What other names is Theanine known by?

2-Amino-4- (ethylcarbamoyl) Butyric Acid, 5-N-ethylglutamine, Gamma-glutamylethylamide, L-Theanine, L-Théanine, N-Éthyl-L-Glutamine, Teanina, Théanine.

What is Theanine?

Theanine is an amino acid found in green tea. It is also found in some mushrooms. It is similar in structure to glutamic acid, another amino acid.

People take theanine by mouth for reducing anxiety and stress, for preventing Alzheimer's disease, for treating attention deficit-hyperactivity disorder (ADHD), and improving mental performance and attention. Theanine is also used for reducing blood pressure, preventing the flu, and improving how well cancer drugs work.

Possibly Effective for...

  • Mental performance. Early research shows that taking theanine before a test can reduce the rate of errors. Also, most research shows that taking theanine along with caffeine increases alertness and improves a person's ability to switch attention between different tasks.

Insufficient Evidence to Rate Effectiveness for...

  • Attention deficit hyperactivity disorder (ADHD). Early research shows that taking 200 mg of theanine (Suntheanine by Taiyo Kagaku) by mouth twice daily for 6 weeks increases restful sleep and decreases nightly activity during sleep in boys ages 8-12 diagnosed with ADHD.
  • Influenza (flu). Early research shows that taking a combination of green tea extract (THEA-FLAN 90S, Ito-en Co.) plus theanine (Suntheanine, Taiyo Kagaku) daily for 5 months may lower the risk of developing the flu.
  • Stress. The effects of theanine on stress are conflicting. Some early research shows that taking 200 mg of theanine before an exam reduces anxiety and may prevent blood pressure from increasing due to stress. Other early research shows that taking 200 mg of theanine twice daily before and during pharmacy practice decreases stress levels. However, another early study shows that taking 200 mg of theanine helps promote tranquility in people who are already relaxed. But it doesn't work in people who are stressed. Reasons for the conflicting results are not clear.
  • Other conditions.
More evidence is needed to rate the effectiveness of theanine for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

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