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Theanine

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.

SLIDESHOW

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How does Theanine 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.

Are there safety concerns?

Theanine is POSSIBLY 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 POSSIBLY 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.

Are there any interactions with medications?


Medications for high blood pressure (Antihypertensive drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Theanine might decrease blood pressure. Taking theanine along with medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.


Stimulant drugsInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Stimulant drugs speed up the nervous system. By speeding up the nervous system stimulant medications can make you feel jittery and speed up your heartbeat. Theanine might work to slow down the nervous system. Taking theanine along with stimulant medications might decrease the effectiveness of stimulant medications.

Some stimulant drugs include diethylpropion (Tenuate), epinephrine, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.

Dosing considerations for Theanine.

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.

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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Reviewed on 9/17/2019
References

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