L-Theanine – Side Effects & Health Benefits

L-Theanine – Side Effects & Health Benefits – Nootropic Supplement For Stress:

L-theanine, a water-soluble amino acid, is found mainly in black and green teas and to a lesser extent in mushrooms. It constitutes between 1% and 2% of the dry weight of tea.

It has structural similarities to Glutamine (the most abundant amino acid in the bloodstream, and it makes up to 30-35% of the amino acid nitrogen in your blood) and both neurotransmitters that are produced from it (glutamate and GABA) and is known to reach the brain and act in the brain following oral ingestion.

In Japan, this supplement has been approved for use in all foods, including soft drinks, herb teas, or desserts (with some restrictions applying to infant foods).

The EFSA – European Food Safety Authority advised negatively on health claims related to this substance and cognitive function, maintenance of normal sleep, alleviation of psychological stress and anxiety, and reduction of menstrual discomfort. Hence, beneficial health claims for this amino acid are prohibited in the E.U.

However, in the United States, it has been approved by the FDA as a supplement, in doses up to 250 mg, and designated as generally recognized as safe (GRAS).

Health Benefits

Improves sleep qualityinsomnia

This substance may be helpful for those struggling with sleep quality or those who want to accomplish as much as possible while undergoing periods of sleep deprivation.

Better cognitive function

Improvements in focus, memory, awareness, and attention span are frequently reported when using this compound, primarily due to the amino acid’s ability to increase Alpha-1 brain activity.

Researchers concluded that the amino acid has the amazing ability to minimize interference from distracting outside stimuli, helping at the same time to focus attention. Individuals in the study were able to concentrate on important projects without getting distracted.

Increases alpha brain waves

Brainwaves are divided into 5 different bandwidths that are believed to create a spectrum of human consciousness. Supplementation with this amino acid has been shown to increase brain α-waves which are linked with reduced anxiety and stress.

The alpha state of the brain indicates peace of mind, relaxation, relaxed focus, and increased serotonin production. People who meditate begin to access the unconscious mind at this stage of relaxation. Alpha waves can also be created by doing aerobic exercise.


This supplement may also find an application in complementary cancer therapies. It not only inhibits the growth of certain tumors but also increases the activity of doxorubicin, pirarubicin, and adriamycin – medications that are used in chemotherapy, lowering at the same time their destructive side effects on healthy tissues of the patient.

Side effects of L-Theanine 

Caffeine Content

it is a stimulant that most people are very familiar with, mainly found in coffee but can also be found in sodas, tea (especially green and dark), chocolate, and some fruits and seeds.

Due to the fact that caffeine is water-soluble and passes easily through cell membranes, it’s very hard for your body to purge caffeine from the cells.

That means that the amount of caffeine from a single cup of coffee or tea remains in your body for a few days. Caffeine intake can cause symptoms like nausea, increased heart rate, excessive urination, vomiting, anxiety, depression, restlessness, difficulty sleeping, or tremors.

Note – caffeine won’t impact everyone in the same way. According to research, someone needs to be taking at least 30 mg of caffeine per day to experience any side effects.

It may decrease serotonin levels

Serotonin is a chemical messenger that’s believed to act as a mood stabilizer. Studies have found links between serotonin and breast milk production, bone metabolism, liver regeneration, and cell division.

A decrease in serotonin in the brain can result in an increase in tension and stress, which is the opposite of the desired effect for anxiety sufferers.

This supplement should be used with caution in people on anti-hypertensive medicines because it decreases blood pressure. Moreover, do not take it with LDL cholesterol-lowering medications.


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