L-Theanine

Common names: L-theanine is also known as Suntheanine.

Efficacy-safety rating:

ÒÒ...Ethno or other evidence of efficacy.

Safety rating:

What is L-Theanine?

Black, oolong, and green tea are produced from the leaves of Camellia sinensis. C. sinensis is native to eastern Asia and is a member of the Theaceae family. This evergreen shrub or tree has dark green, serrated-edged leaves. L-theanine is a unique amino acid found only in the tea plant.

What is L-Theanine used for?

Second only to water, tea is one of the most widely consumed beverages in the world. With the exception of a mushroom (eg, Xerocomus badius) and certain species belonging to genus Camellia (C. japonica and C. sasanqua), L-theanine is a unique amino acid found only in the tea plant. L-theanine was discovered in 1949 to be a constituent of tea leaves. Taiyo Kagaku Co. Ltd., Japan, has developed an enzymatic method to manufacture synthetic L-theanine (Suntheanine).

L-theanine was approved in Japan in 1964 for unlimited use in all foods (including chocolates, soft drinks, herb teas), except infant foods. It also provides a unique umami (brothy or savory) taste and flavor to green tea infusion. L-theanine has been used in cosmetics to moisturize the skin.

L-theanine may help relieve stress by inducing a relaxing effect without drowsiness. L-theanine as been shown to promote the generation of alpha-brain waves, an index of relaxation. It may also boost natural resistance to microbial infections and perhaps even tumors. Researchers suggest further isolating and refining L-theanine from tea to use it as a drug to boost the infection defense of the body. Although limited, there is clinical evidence to support these claims.

What is the dosage of L-Theanine?

Based on the alpha-wave study, a dose of 50 to 200 mg may provide a relaxation effect. No dosage of L-theanine is suggested for enhanced immune system functioning; however, volunteers in a pilot study consumed approximately 600 mL of tea a day.

Is L-Theanine safe?

Avoid use in patients with known hypersensitivity reactions to L-theanine.

Information regarding safety and efficacy in pregnancy and lactation is lacking.

None well documented.

L-theanine is enzymatically synthesized by Taiyo Kagaku Co. Ltd., Japan and is extensively marketed in over 50 food products (eg, chocolate, soft drinks, herb teas) in Japan. Thus far, it has not resulted in any reported adverse reactions.

Tests fail to reveal any toxicities with L-theanine.

References

Copyright © 2006 Wolters Kluwer Health

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