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Science-Backed Benefits of L-Theanine

Science-Backed Benefits of L-Theanine

Many people enjoy a cup of tea to relax or to prepare for the day ahead; but did you know that more than the warm mug between your hands and slowly swirling steam help you to de-stress and prep for the day?

Both green and black tea contain, among other beneficial constituents, an amino acid called theanine.

Similar to the effects of, and working in synergy with lemon balm, theanine has been shown to promote relaxation without drowsiness, all while boosting cognitive function.

What better way to test the effects of theanine than by asking people to do math (math anxiety!)?

A study from Japan demonstrated the dramatic effects of theanine to promote tranquility.  In this study, researchers assigned a mental arithmetic task to each subject on four separate occasions, inducing “math anxiety.” Subjects using theanine experienced a reduction in heart rate (that “fight-or-flight” feeling) in response to the math testing, compared with those receiving placebo.1

Feeling calm is great, but remaining sharp is critical. Theanine actually sharpens your pencil while keeping you cool, calm, and collected.

Another study originating from Japan showed theanine’s ability to support cognitive function. 

In this study, subjects who chewed gum containing theanine displayed significant increases in brain wave activity associated with focus and attention, as compared with individuals who chewed gum that did not contain theanine, which suggests that theanine has the ability to promote attention to tasks, while at the same time minimizing attention to distracting stimuli.2

How is that possible, you ask? The U.S. Air Force wanted to know the same thing! So they undertook a study to discover exactly where theanine produced effects within the brain. It had previously been shown that when someone concentrates on a task, brain waves in the alpha region of the EEG (electroencephalogram) increase.

Subjects in this study performed a task while researchers collected data from the EEG. When the subjects took theanine prior to the task, they showed a decrease in alpha wave background activity, but a prominent increase in the important alpha activity related to the attention-requiring tasks. This means that theanine helps you focus on critical things, while lessening the attention paid to potential distractions.3


  1. Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007 Jan;74(1):39-45.
  2. Yagyu T, Wackermann J, Kinoshita T, et al. Chewing-gum flavor affects measures of global complexity of multichannel EEG. Neuropsychobiology. 1997;35(1):46-50.
  3. Gomez-Ramirez M, Higgins BA, Rycroft JA, et al. The deployment of intersensory selective attention: a high-density electrical mapping study of the effects of theanine. Clin Neuropharmacol. 2007 Jan;30(1):25-38.
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