Theanine Side Effects
Can Too Much Be Harmful?

Despite its being a synthetic supplement, scientists have not observed any theanine side effects since its widespread use starting in 1964, even when used in high quantities.

Few people have heard about theanine, but this supplement probably ranks amongst  the safest in existence.

Enzymatic Process

Although theanine is an important tea constituent, theanine tablets are made synthetically using enzymes in laboratories rather than being extracted from tea leaves.

This means that you don't have to worried about environmental pollution or herbicide contamination of tea leaves.

However, given that it is manufactured synthetically, is there cause for concern? Can consuming too much theanine cause side effects?

To answer this question, we need to look into the safety record in long term human usage.

Unlimited Use

Synthetic theanine has been licensed for unlimited use in all foods (except infant food) in Japan since 1964. These include chocolate, soft drinks and herbal teas.

This is impressive. In Japan, food ingredients need to undergo extensive testing before they are approved for unlimited use.

Studies have found theanine to be harmless, even at very large quantities. Tests include the Acute Toxicity/LD50 Determination, which uses super high concentrations of 5 grams per kilogram.

(That is the equivalent of a 60 kilogram adult consuming 300 grams of theanine a day!)

FDA Affirmation

In 2007, theanine received the GRAS affirmation (Generally Recognized as Safe) from the United States FDA for its use in a number of food and beverage products.

Long History

Amazingly, for the past 40 years, there have been no scientific reports of theanine side effects.

Drug Interactions

There have been no known interactions of theanine with other prescriptions or over the counter drugs.

You may be surprised to learn that past studies have found that theanine helps improve the efficacy of anti-cancer drugs by enhancing their effectiveness and reducing their side effects.

This may be due to the relaxing properties of theanine, which reduces anxiety in patients' minds, and helps them sleep soundly at night, therefore enhancing the body's self-healing process.

What's The Catch?

I have been asking myself this question: Is this a magic drug or something? Can it really have no side effects?

I guess the answer lies in the real nature of theanine. You see, it is an amino acid, which are the building blocks of protein, the stuff you and I are made of.

Theanine is related to glutamine, the most abundant naturally occurring amino acid produced by the human body. Other sources of glutamine include chicken, eggs, spinach and beans.

Theanine helps relax the mind, and when you feel relaxed, things seem to take care of themselves.

Recommended Dosage

Most credible sources recommend taking 50 to 200 milligrams a day with or without food, 2 to 3 times daily as needed.

Studies have also reported good results at up to 400 milligrams a day.

At high concentrations (say 1000 milligrams), theanine may make you feel over-relaxed. So beware, especially if you are involved in manual work.

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Leek Raj Jujena, Chu D, Okubo T, Nagato Y, and Yokogoshi H (1999). L-theanine – a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology. 1999;10(6-7):199-204.

From The Experts. Suntheanine.

Yokogoshi H, et al. (2001). Institute for Traditional Medicine ( Theanine effects on premenstrual syndrome. Amino Acid Supplements IV: Theanine. Subhuti D. Referencing: Proceedings of the Nogei Kagaku Kai, Bioscience, Biotechnology, and Biochemistry. 2001;75:166.

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