L-theanine Helps Reduce Stress and Anxiety

L-theanine is an amino acid found almost exclusively in green tea and is likely responsible for the calming effects many people experience when drinking green tea1. Unlike anti-anxiety medications like Xanax, L-theanine produces relaxation without causing drowsiness. L-theanine has also been shown to help with mood, cognition and memory, all topics we will discuss in later blogs. We will start this blog by talking about the effect L-theanine has on brain waves and its relationship to relaxation.

L-theanine and its Effect on Brain Waves

A study with sixteen participants taking either 50 mg of L-Theanine or a placebo found a significant increase in Alpha waves of the brain in the participants taking L-Theanine2. Alpha waves are associated with relaxed states, such as meditation. The Alpha waves seen during meditation are different than the Alpha waves we experience while sleeping. Increased Alpha waves while awake is associated with a calm but alert and non-drowsy state, making it markedly different than the effects induced by prescription anti-anxiety medications.

L-theanine and Stress Reduction

L-theanine may help reduce stress. A study subjected twelve male college students to arithmetic problems for twenty minutes. The participants rated this activity as causing an increase in stress3. The participants taking 200 mg of L-theanine reported a reduced stress response from the stress test (performing arithmetic problems) and showed a reduced physiological stress response compared to those taking a placebo.

L-theanine Affects the Anxiety Reducing Neurotransmitter GABA

Although not as strong as the link between L-theanine and increased Alpha waves, there is some research in rats showing L-theanine may affect neurotransmitters, in particular, GABA4. A neurotransmitter is a brain chemical that sends signals to the body, affecting heartbeat, digestion, mood, anxiety levels, etc. GABA is a neurotransmitter known to counteract the stimulatory neurotransmitter glutamate5.  When someone becomes anxious, their glutamate levels increase. An increase in GABA levels, as potentially seen in subjects taking L-theanine, has an opposing effect on the glutamate levels, lowering them and causing a reduced level of anxiety.

Dosage of L-Theanine Required to Experience Anti-Anxiety Effects

Studies have shown that L-theanine works best in people with high levels of anxiety. Most studies showing that L-theanine reduces anxiety gave subjects 50 mg, 200 mg or 600-800 mg per day. A cup of green or black tea has an average of 8 mg to 24 mg per cup. If planning on taking 200 mg or more of L-theanine per day a supplement would be needed.

As of now, there are no known dangerous limits for maximum intake of L-theanine per day.  


The amino acid L-theanine has been shown to reduce anxiety and stress in both animals and humans. L-theanine causes an increase in brain Alpha waves, which are known to have a relaxing effect on people, similar to meditation. Unlike benzodiazepines like Xanax, L-theanine does not cause drowsiness and keeps subjects alert. Preliminary studies in rats have shown that L-theanine may increase levels of the neurotransmitter GABA, known to reduce anxiety by countering the stimulating effects of the neurotransmitter glutamate.


  1. Juneja, L. R., Chu, D. C., Okubo, T., Nagato, Y., & Yokogoshi, H. (1999). L-theanine—a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology10(6), 199-204.
  2. Nobre, A. C., Rao, A., & Owen, G. N. (2008). L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pacific journal of clinical nutrition17(S1), 167-168.
  3. Kimura, K., Ozeki, M., Juneja, L. R., & Ohira, H. (2007). L-Theanine reduces psychological and physiological stress responses. Biological psychology74(1), 39-45.
  4. Lardner, A. L. (2014). Neurobiological effects of the green tea constituent theanine and its potential role in the treatment of psychiatric and neurodegenerative disorders. Nutritional neuroscience17(4), 145-155.
  5. Lydiard, R. B. (2002). The role of GABA in anxiety disorders. The Journal of clinical psychiatry64, 21-27.

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By | 2018-07-04T15:02:54+00:00 June 25th, 2017|Articles, Mental Health, Nutrition, Supplements|

About the Author:

Robert recently graduated from Montclair State University with a BS in Nutrition and Food Science. Robert enjoys researching various nutrition/wellness topics and has his own blog at: RobsHealthCorner.com. In his free time, Robert likes to read science fiction, watch horror movies and keep in shape by jogging and using workout DVD's like T25. To learn more about Rob, visit his website http://robshealthcorner.com/about-me/

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