A Review Of L-Theanine For New Users

What Is L-Theanine?

L-Theanine, sometimes simply referred to as theanine, comes from evergreen trees in Asia and is found on dark-green,serrated-edged leaves. It amounts to one to two percent of the weight of these leaves. The material was found within tea back in 1949, providing a savory flavor to green tea concoctions. Japan approved it for unlimited uses as early as 1964.

L-Theanine is found to have a similar chemical structure to glutamate, a natural amino acid which transmits nerve impulses to the brain. Some of the effects of L-Theanine seem similar to glutamate as well. Capable of crossing the blood-barrier within 30 minutes, L-Theanine provides relief to a number of emotional states. The chemical has traditionally been used to help out in stress relief, anxiety, and depression. It also helps boost cognitive abilities similar to caffeine and often gets used in conjunction with caffeine.

It can be classified as a nootropic, which are cognitive enhancers used to help focus and concentration of the brain. L-Theanine is still considered a natural substance, so it gets classified as a supplement more easily than other nootropics.


L-Theanine has been shown to improve intelligent performance which ingested in conjunction with caffeine. It helps people stay awake and alert and aid in limiting cognitive impairment. As a result, several beverage manufacturers sell drinks containing it and market their products as helping people concentrate better.

L-Theanine tends to increase activity in the alpha frequency band, thus getting the mind to relax without making it drowsy at the same time. The amino acid also enhances a person’s mood, helping to stop depression, while also lowering blood pressure. Theoretically, L-Theanine could help a body’s immune system by boosting the capabilities of gamma delta T-cells which fights against infection.

Recommended Dosage

When it comes to correct dosage, the usual amount taken in a day by adults ranges from 200 mg to 400 mg. More can be done, but a maximum of 1,200 mg is preferable. Usually, it gets sold in drug stores at around 200-250 mg when used as a daily supplement.

Side Effects

There have been few reported side effects in regards to L-Theanine. The more common ones mentioned are headaches, dizziness, and gastrointestinal issues such as heartburn, indigestion, and constipation. Others have found that L-Theanine may increase focus but blunts response time. It generally decreases blood pressure, so it would be perfect for someone with hypertension, but not in conjunction with anti-hypertension medicine.

Since it is found in tea leaves, it may be better to drink tea rather than acquire it as a supplement. In short, it isn’t too hard to acquire some of it. If doing chemotherapy, it wouldn’t be advisable to take it because it can increase the activity of some cancer agents.

Short-Term & Long-Term Use

Some use it in conjunction with caffeine in order to blunt some of its effects. Caffeine can help stimulate energy and focus, but it stays in the body for up to 10 hours. That can create situations of insomnia during the night. L-Theanine can be used to limit those situations. It doesn’t cause people to sleep more but does help them sleep better. Combined with caffeine or on its own, it can help burn calories and suppress weight gain.

L-Theanine is thought of as an antidote to alcohol, particularly to the liver. The amino acid helps to restore the liver’s function as a detoxifier, especially in dealing with blood alcohol levels. For potential long-term use, some use it to treat against Alzheimer’s disease due to its supposed cognitive enhancement. Also, it is said to help make drugs combating cancer more effective. L-Theanine raises moods and lessens stress, two areas which could contribute to memory loss.


Despite its presence in tea leaves, much is still unknown about L-Theanine. Some of the statements tend to refute the known research. Most of the unknown deals with how much L-Theanine improves health over the long-term. Though there has been speculation that L-Theanine may have positive benefits for the cardiovascular system and help in cancer prevention, limited information supports these claims.

Extensive studies have been done with the amino acid, particularly with placebo trials and using rats as test subjects. Human-subjected trials have been uncommon so far, but there have been few adverse effects in the vast majority of the studies on L-Theanine, leading to the belief that it is relatively safe.

This chemical is regarded as safe for adults when used in moderate quantities. Studies on test rats tend to back this belief up. Even repeated, extremely high doses of L-Theanine cause little to no harmful effects, both physically and psychologically.

A placebo-controlled trial has shown adding L-Theanine to antipsychotic medication can reduce symptoms associated with schizophrenia. Some point out that many studies with L-Theanine have been done in concert with caffeine. Thus the belief that its usage supporting lower blood pressure, anxiety, mood, and cognition to be unclear scientifically.

Legal Status

Views about L-Theanine vary. Japan has accepted it for half a century now. The Food and Drug Administration approves it as a supplement and has granted it GRAS status, standing for generally recognized as safe.

On the other hand, Germany object to its inclusion in beverages. The European Food Safety Authority (EFSA) has given negative indications toward L-Theanine’s health claims, thus prohibiting such claims in the European Union.

Final Thoughts

Because it comes from a natural source and there have been few results portraying it negatively, L-Theanine is generally regarded as safe and effective for its main purpose of helping to treat anxiety and improve concentration. It may be easier to drink tea instead of using it as a supplement for small concentration boosts.

The debate as to how it can improve long-term outlook is still ongoing, but that shouldn’t discourage some potential users. Because of its general view of safety and short-term effectiveness, L-Theanine can be helpful in creating a more relaxing interior body chemistry while providing a boost to focus and concentration. Until major negative effects come to light, it can be continued to be used for such situations.

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