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*This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


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.

How does it work?

Theanine has a chemical structure very similar to glutamate, a naturally occurring amino acid. Glutamate helps transmit nerve impulses in the brain. Some of the effects of theanine appear to be similar to glutamate, and some effects seem to block glutamate. Theanine may also affect some brain chemicals called GABA, dopamine, and serotonin.

Traditionally used for

Mental performance.
Attention deficit hyperactivity disorder (ADHD).
Influenza (flu).


By Mouth:

Mental performance: A single dose of 100 mg of theanine before a test has been used (91747). Theanine has also been used in combination with caffeine. Combination doses have ranged from 30-100 mg of caffeine and 12-100 mg of theanine.

Possible Side Effects

Theanine is SAFE when used by mouth, short-term. Doses of up to 250 mg of theanine have been safely used one time per week for 3 weeks. Also, a specific combination product containing theanine and other green tea ingredients has also been used safely when taken once daily for up to 5 months. It is not known if theanine is safe when used for longer periods of time. Theanine may cause mild adverse effects, such as headache.

Special Precautions & Warnings

Pregnancy and breast-feeding: There is not enough reliable information about the safety of using theanine if you are pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: Theanine is SAFE for children. Doses of 200 mg of theanine have been safely used twice daily for up to 6 weeks.

Low blood pressure: Theanine might lower blood pressure. In theory, theanine might increase the risk of blood pressure dropping too low in people prone to low blood pressure. If you have low blood pressure, discuss theanine with your healthcare provider before starting it.

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