Alzheimers Home > L-Theanine

L-theanine is an amino acid found in tea and also used in dietary supplements. It is often claimed to be beneficial for treating Alzheimer's disease, high blood pressure, and anxiety. L-theanine may increase serotonin and GABA levels, lower norepinephrine levels, and protect brain nerves from damage seen in Alzheimer's. However, there is currently not enough evidence to confirm the effectiveness of this supplement for any use.

What Is L-Theanine?

L-theanine (also known as just 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 L-Theanine for more information on what it is used for, including additional uses.)

How Does L-Theanine Work?

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

Is It Effective?

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

Dosing Information

A safe and effective dose of this supplement has not been established. Be sure to follow the specific instructions on your particular product.
(Click L-Theanine Dosage for more information.)
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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