Stress makes us feel miserable.

It can have a devastating impact on emotional and physical health.

Chronic stress increases cardiovascular risk, diminishes immune function, impairs cognition, induces gastrointestinal problems, contributes to depression, and more.¹

A compound found in green tea can help. This amino acid, named L-theanine, promotes stress relief, calm, and relaxation—without causing drowsiness.²

L-theanine is rapidly absorbed and cleared from the body. This causes some people to take multiple doses throughout the day to achieve sustained levels.

Using an immediate- and extended-release technology, scientists have found a way to allow L-theanine to stay in the body for up to six hours.

One study in moderately stressed adults found that a single dose of this form of L-theanine led to a greater increase in indicators of relaxation compared to placebo.³

Deadly Effects of Chronic Stress

Repeated or unrelenting stress leads to a higher risk for cardiovascular disease, diminished immune function, and damaging inflammation.^1,4

One of the most widely recognized health effects of chronic stress is an increased risk of heart disease.

Chronic stress has been shown to impair cardiac⁵ function and can cause high blood pressure, arrhythmia, and vascular inflammation leading to atherosclerosis and stroke.⁶

Most anti-stress or anti-anxiety drugs cause sedation and other side effects and can be addictive.⁷ So, scientists have been investigating plant extracts that may safely reduce stress and anxiety without side effects.

L-Theanine Lowers Stress

Researchers have long been investigating an amino acid called L-theanine that is found primarily in the leaves of green tea. Studies show it is able to cross the blood-brain barrier.²

L-theanine has demonstrated anti-stress effects, including reductions in perceived stress and markers of stress response like blood pressure, heart rate, cortisol, and patterns of brain activity.⁸

This confirms earlier work that showed subjects taking L-theanine reported significantly less subjective stress than those taking placebo.⁹

Research has revealed that L-theanine generates a sense of relaxation, with alertness, through at least two mechanisms:^10-18

1. Enhances production of the inhibitory (relaxing) neurotransmitter GABA, or gamma amino butyric acid.
   (GABA then influences levels of dopamine and serotonin that also produce relaxing effects.)
2. L-theanine increases the brain’s production of alpha brain waves. This creates a state of deep relaxation with mental alertness.

Results of Human Studies

Human trials confirm that L-theanine has relaxing properties that relieve stress.^3,19

In one study, pharmacy students undergoing high-stress clinical training who took 200 mg of L-theanine twice daily reported feeling significantly less stress than those who took a placebo.⁹

Another clinical trial was done with healthy men and women, aged 21 to 47, who were not considered to be particularly stressed before the study.¹⁹

Each volunteer was subjected to alpha brain wave testing, which measures wakeful relaxation, and heart rate measurements. Then, a stress test was given and measurements were retaken.

Next, half the group was given 200 mg of L-theanine, and half was given a placebo. The stress test was conducted twice more over the following 90 minutes. The alpha brain wave and heart rate tests were also repeated. Results showed that:¹⁹

• Relaxed wakefulness (measured by alpha brain wave activity) increased with L-theanine but not with the placebo,
• Tension and anxiety were reduced to a greater degree in the L-theanine group, and
• Heart rates were lowered by L-theanine, compared to placebo, a further sign of stress reduction.

A randomized, triple-blind, placebo-controlled, crossover study was done on healthy but moderately stressed adults aged 19 to 60 years.³

Study subjects took a single dose of 200 mg of an extended-release form of L-theanine, or placebo. All these volunteers took a mental arithmetic test in order to induce mental stress. There was a seven-day washout period between the L-theanine test and the placebo test.

Alpha brain wave activity, salivary cortisol levels, and vital signs were recorded before and after participants took the arithmetic test.

Increases in heart rate, blood pressure, and self-reported stress and anxiety confirmed that subjects experienced stress during the stressful mental test. However, compared to the placebo, 200 mg of L-theanine led to greater alpha wave activity, indicating a higher level of relaxation without drowsiness, just three hours later.³

The “calming response” in brain activity was further supported by greater decreases in salivary cortisol levels, compared to placebo.

In other words, L-theanine reduced feelings of stress and physical markers of stress in the body.

Summary

Stress reduces quality of life and boosts the risk of chronic disorders and premature death.

L-theanine, an amino acid found in green tea, lowers stress and promotes relaxation while maintaining alertness.

Unlike anti-anxiety drugs, L-theanine safely relieves stress without causing drowsiness.

L-theanine is rapidly absorbed, but then rapidly cleared from the body. Using an immediate- and extended-release technology, scientists have found a solution to this, allowing L-theanine to stay in the body for up to six hours.

Human trials have shown that L-theanine reduces signs of stress after just a single 200 mg dose.

If you have any questions on the scientific content of this article, please call a Life Extension Wellness Specialist at 1-866-864-3027.

References

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3. Evans M, McDonald AC, Xiong L, et al. A Randomized, Triple-Blind, Placebo-Controlled, Crossover Study to Investigate the Efficacy of a Single Dose of AlphaWave((R)) L-Theanine on Stress in a Healthy Adult Population. Neurol Ther. 2021 Dec;10(2):1061-78.
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