How L-Theanine Busts Stress

A Compound in Green Tea Stands Up to Stress

Wadded up paper with a "stress" sign

Chronic stress threatens our health, shortens our life, and erodes our happiness. The more we can do to reduce our stress the better. Certainly we should all be trying to manage the sources of stress in our lives—work, family responsibilities, money, etc. And we should definitely strive to improve our coping skills so that when stress does come our way, we can keep it in check.

Sometimes, however, we simply need additional support, whether through talk therapy, more down time, or nutritional supplements. Recent research is highlighting the non-protein amino acid L-theanine, a primary constituent of green tea, as a promising and natural stress-reducing substance. 

How L-Theanine Busts Stress

 Studies are showing L-theanine is able to reduce the psychological and physical symptoms of stress in adults, as well as in children with ADHD. It affects various mechanisms in the brain, improving the brain’s response to stress. In fact, it’s one of the few substances able to cross the blood-brain barrier.

Animal studies suggest that L-theanine influences brain levels of dopamine (a neurotransmitter associated with feelings of love, joy, and pleasure) and serotonin (a neurotransmitter that regulates mood, irritability, impulse, and memory). These studies also show that L-theanine can reduce blood pressure in hypertensive rats. Hormones, stress, and blood pressure have a sensitive relationship. When you are stressed, hormones flood your body, causing your heart to beat faster, your blood vessels to narrow, and your blood pressure to increase.

A study from the Unilever Food and Health Research Institute in the Netherlands used electroencephalograph (EEG) testing to examine L-theanine’s effect on brainwaves. Beta brain waves are associated with unease and stress, while alpha brain waves promote a relaxed, wakeful state. Individuals who took 50 milligrams of L-theanine registered dramatically more alpha wave activity than did those who took a placebo pill.

These results suggest that L-theanine helps to relax the mind without causing drowsiness and while promoting concentration. Another study showed that L-theanine also exerts an anti-stress effect by stopping L-glutanic acid from attaching to glutamate receptors in the brain, thereby helping to suppress neuron excitation.

In 2013, the journal Pharmacology, Biochemistry and Behavior published a very validating study on L-theanine’s impact on stress. Pharmacology is considered a high-stress training program, so researchers randomly gave fifth-year pharmacology students 200 milligrams of L-theanine twice a day or a placebo pill one week before their pharmacy practice, and continuing for 10 days during the practice.

At the end of the study period, students given L-theanine had significantly lower subjective stress as measured with salivary α-amylase activity (sAA), an indicator of sympathetic nervous system activity.

Supplementing with L-Theanine

By all means, drink green tea rich in L-theanine, but researchers estimate that in order to get the anti-stress benefits of L-theanine, you’d have to drink 10 to 15 cups a day. However, experts caution that the effects of an L-theanine supplement could be unpredictable when mixed with other medications or supplements, so consult your doctor or integrative health physician before adding L-theanine to your supplement stash.

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