Stress Relief with L-Theanine

Guest article by Dr. Lise Alschuler and Karolyn A. Gazella

There seems to be no end to the health benefits found in a cup of green tea. One of them is the sense of calm it can bring—not just because of the act of slowing down and sipping, but also because it contains a soothing amino acid, L-theanine. In supplement form, L-theanine is even more powerful, making it a popular stress-reliever. One of the most studied forms of L-theanine is a branded ingredient known as Suntheanine®.

In several human clinical trials, L-theanine has promoted relaxation by increasing alpha brain waves and decreasing beta brain waves. Alpha brain waves are associated with a relaxed, yet alert and focused brain activity. Beta brain waves, on the other hand, are markers of a more excited and non-focused state.

Stress-induced anxiety and elevated blood pressure

Stress isn’t just a state of mind—it has real physical effects in the body. When we experience stress, our nervous system produces more hormones that increase blood pressure and feelings of tension. In a randomized, placebo-controlled study published in 2012 in Psychological Anthropology, 16 healthy adults took either 200 mg of L-theanine (Suntheanine) with placebo, 100 mg caffeine with placebo, or placebo only. This was a crossover study, meaning participants serve as their own control. That’s a way of strengthening a study even with a small number of participants.

Each subject participated in various computer and arithmetic tasks that caused mental strain. In addition, the participants underwent physical stress by submerging a hand in ice water for one minute.

Their blood pressure was recorded throughout all of the tasks, and the participants completed questionnaires to assess their feelings of stress. L-theanine is absorbed and active within 30 minutes of taking it, with a peak activity in one hour, and it lasts for 1 to 11⁄2 hours. Caffeine has a similar, if somewhat more rapid and more prolonged absorption profile. Based on this, the researchers provided the supplements 36 minutes before the end of the mental tasks so that the supplements’ maximal effect would match the peak of stress caused by the tasks.

This study found that taking the oral supplement of L-theanine significantly reduced rises in blood pressure in participants who experienced stress as a result of the mental tasks. This is particularly important for adults who show a large blood pressure response to psychological stress, because these individuals are at greater risk of developing high blood pressure as they age. L-theanine also reduced feelings of stress and anxiety caused by the stressful tasks. Interestingly, the L-theanine did reduce the rise in blood pressure caused by physical stress as well. The caffeine and placebo did not result in decreased blood pressure or tension.

This study suggests that L-theanine decreases anxiety and reduces rises in blood pressure that can accompany mental and emotional stress. Given this, L-theanine may be a good part of an overall wellness and heart disease prevention plan—particularly in people who are under increased mental and emotional stress.

L-theanine safety and availability

Unlike other stress-reducing and sleep-enhancing supplements or drugs, Suntheanine does not cause drowsiness. Suntheanine has also been affirmed as GRAS (Generally Recognized as Safe) with Letter of No Objection from the FDA (GRN 000209). Suntheanine is made using a special patented enzymatic process that ensures consistency and effectiveness. It is an ingredient in many dietary supplements that promote relaxation.

Note: This article is excerpted with permission from Five to Thrive, a digital magazine published by Dr. Lise Alschuler and Karolyn A. Gazella. For more information, visit

Dr. Lise Alschuler and Karolyn GazellaDr. Lise Alschuler is a highly respected naturopathic oncologist and a sought-after speaker to both consumers and healthcare professionals on the topic of integrative cancer prevention and treatment. Karolyn A. Gazella is an accomplished natural health research journalist and the publisher of Natural Medicine Journal. Together Alschuler and Gazella have written three books including their latest, The Definitive Guide to Thriving After Cancer (Random House 2013). They also co-host a popular internet radio show on the Cancer Support Network. Lise and Karolyn have been collaborating and creating their multi-media initiative for more than a decade. They are both cancer survivors. For more information visit

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