L-Theanine supports relaxation and eases stress in study participants

October 20, 2021

L-Theanine is an amino acid found in green tea leaves. This nutrient has been shown to help increase the secretion of serotonin and dopamine when it crosses the blood-brain barrier. It has also been studied for its ability to increase alpha brainwaves, with are linked to rest and relaxation.

This is especially important in the midst of a global pandemic. During this time, 75% of Americans have reported issues relating to stress, including irritability, change in appetite, sleep disruption or changes and negative thoughts.

A recent triple-blind, placebo-controlled, randomized trial looked at men and women aged 19 to 60. These participants were given either 200mg of L-Theanine or placebo. They were then given a mental arithmetic test, where they had to subtract from 700 by 7, all while keeping pace with a metronome. After the test, they were given two questionnaires regarding their stress levels. Researchers also collected saliva samples.

The participants then received another dose of either L-Theanine or placebo, followed by another round of the arithmetic test. In addition to the saliva test and stress questionnaire, blood pressure and heart rate were also measured. The researchers also performed an alpha wave EEG three hours after the participants took the placebo or L-Theanine. The participants then underwent a weeklong washout period before repeating the protocol again.

Ultimately, the study found that a single dose of L-Theanine had significant impacts on salivary cortisol, brainwave activity and self-reported stress.