Theanine

Theanine is a dietary supplement used to treat various conditions, including high blood pressure, anxiety, and Alzheimer's disease. It is an amino acid found in tea that appears to increase serotonin and GABA levels in the brain and protect brain nerves from damage caused by Alzheimer's. At this time, there is not enough scientific evidence to evaluate the safety and effectiveness of theanine supplements.

 

What Is Theanine?

Theanine (also known as L-theanine) is an amino acid found in tea. It is also used in dietary supplements and is claimed to be useful for a variety of different conditions such as anxiety, Alzheimer's disease, and high blood pressure (hypertension).
 
(Click Benefits of Theanine for more information on what theanine is used for, including additional theanine uses.)
 

Side Effects of Theanine

There are no known side effects of theanine. However, this probably reflects a lack of clinical studies with theanine (not a real absence of side effects).
 
(Click Theanine Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Theanine Safety Information

Some people may be more likely to experience problems due to theanine. Therefore, you should talk with your healthcare provider before taking theanine if you have:
 
  • Kidney disease, such as kidney failure (renal failure)
  • Liver disease, such as liver failure, cirrhosis, or hepatitis
  • Any other serious or chronic health condition
  • Any allergies, including allergies to food, dyes, or preservatives.
    •  
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Is Theanine Safe? for more information, including any available theanine warnings and precautions.)
 

How Does Theanine Work?

It is not exactly clear how theanine works. It might work for anxiety by increasing levels of gamma-aminobutyric acid (GABA), a brain chemical that is naturally calming. Theanine may also increase serotonin levels in the brain. It is thought that theanine may also protect nerves in the brain from damage seen in Alzheimer's disease. In animals, Theanine lowers norepinephrine levels, which may help lower blood pressure.
 

Is Theanine Effective?

There is not yet enough scientific evidence to evaluate the effectiveness of theanine for any use.
 
(Click Does L-Theanine Work? for more information.)
 

Theanine Dosing Information

A safe and effective theanine dose has not been established. Be sure to follow the specific instructions on your particular theanine product.
 
(Click Theanine Dosage for more information.)
 

Theanine Drug Interactions

Theanine can interact with a few medications (see Drug Interactions With Theanine).
 

What If I Take a Theanine Overdose?

It is not known exactly what to expect from a theanine overdose. If you think you may have taken too much theanine, seek medical attention immediately.
 
(Click L-Theanine Overdose for more information.)
 

Theanine: Storage Methods

Refer to the label of your individual theanine product for information on how to best store theanine. Keep theanine and all other medications or supplements out of the reach of children.
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;