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What is L-Theanine? Advantages, Natural Sources, and Dosage.



What is L-Theanine?

Theanine (primarily known as L-Theanine) is a non-protein amino acid found naturally in the Green Tea and Black tea plant and is also available as an anti-depressant/anti-anxiety drug. There are around 900 different non-proteinogenic amino acids derived from plants.

L-Theanine is generally considered safe when used in moderation. It is available in supplement form and is often combined with Caffeine to provide a calming effect without causing drowsiness.

Science of L-Theanine:

L-Theanine can cross the blood-brain barrier. When taken orally, it enters the brain, activates the GABA receptors, and increases GABA neurotransmitters and dopamine levels.

Activation of GABA Receptors decreases the extra activity of brain impulses resulting in relaxation of the mind, leading to less anxiety and a feeling of peacefulness.

L-Theanine also affects the Caffeine receptors in the brain, binds with them, and blocks those receptors, which leads to high blood pressure after Caffeine intake but doesn’t affect the other stimulations of Caffeine, like Alertness.

What are the main advantages of Theanine?

L-Theanine has various positive benefits on the human body, some of which are listed below:

Reduce Anxiety and Depression:

Due to its agonist property to GABA receptors, L-Theanine is an anti-anxiety and anti-depressant supplement in many countries worldwide.

People who drink Green Tea and Black Tea more often feel a significant reduction in overall body anxiety and a sense of mental relaxation.

Improves Quality Sleep:

One study reveals that intake of L-Theanine and the GABA Supplement improves sleep quality among individuals, reduces sleep latency, and prolongs sleep duration.

It proved very helpful in treating patients suffering from sleep disorders (Insomnia).

Verbal Fluency:

A four-week experiment on humans revealed that L-Theanine, if taken 200mg/day, can significantly improve verbal and letter fluency, especially among people with cognitive issues.

L-Theanine can promote mental health in people with stress-related disorders and cognitive impairments. However, more research and thorough investigation are needed.

Mental State:

According to a study, 50-100mg of L-Theanine can significantly reduce mental stress, improve mood, and sharpen memory and daily life activity.

Patients suffering from a disease like Schizophrenia can also add this to their medication after consultation with their respective Doctors.

Reduce Chances of Heart Attack:

Studies support L-Theanine positive effects on the Heart, as It decreases the cortical neuron excitation in the brain initiated by the activation of glutamate receptors.

L-Theanine also reduces the heart rate, blood pressure, and chances of other cardiovascular diseases associated with high cholesterol.

However, patients with Bradycardia (Slow Heart Beat) and other heart conditions should use L-theanine cautiously after consulting their physician.

Help in Weight Loss:

L-Theanine and Caffeine proved very helpful during the weight loss journey. Theanine reduces the adverse effects of Caffeine while restoring energy and Alertness simultaneously.

Many famous weight loss Supplement brands use this as one of the main ingredients in their weight loss formula.

Cancer Treatment:

Due to its calming effect, L-theanine may also be used as a drug to help patients with cancer to sleep better at night. Chemotherapy is a painful but effective treatment to cure cancer.

200mg-400mg L-theanine can be used to reduce pain.

What are the possible adverse effects of L-Theanine?

Studies haven’t found any potential significant adverse effects of L-Theanine. However, L-Theanine is present naturally in Green tea leaves. So, drinking too much Tea can cause stomach upset like loose motion.

Patients with the condition of Bradycardia should consult their doctors before taking this.

L-Theanine is generally considered safe and well-tolerated when used in appropriate doses. However, certain people may experience some mild side effects. Here are some possible adverse/side effects of L-Theanine:

Headaches: Some people may experience headaches as a side effect of L-Theanine. This side effect is usually mild and goes away on its own.

Nausea: Nausea is another potential side effect of L-Theanine but is also usually mild and temporary.
Dizziness: Some people may experience dizziness or lightheadedness after taking L-Theanine.

Low blood pressure: L-Theanine has been reported to lower blood pressure in some people. If you take medication to lower your blood pressure, you should speak to your healthcare provider before taking L-Theanine.

Sleepiness: L-Theanine may cause drowsiness in some people, especially in high doses.

It’s important to note that these side effects are rare and usually mild. However, More research is required.

What is the recommended dosage of L-Theanine supplement?

The recommended dosage of L-Theanine supplement may vary depending on age, health status, and the reason for use.

Generally, a safe and effective dosage of L-Theanine is between 100-400 mg daily. It is recommended to start with a lower dose and gradually increase it over time, as needed.

What are the natural sources to get L-Theanine?

Theanine is present in the Green Tea plant, Black Tea, and some Mushrooms.

Supplements in the form of tablets are also available in the market.

Drug Interaction with L-Theanine:

L-Theanine is generally considered a safe and well-tolerated supplement but may interact with certain medications and supplements. Here are some examples of drugs and supplements that may interact with L-Theanine:

Drugs for high blood pressure: L-Theanine may lower blood pressure in some people. So, take medications for high blood pressure, such as calcium channel blockers or ACE inhibitors. It would be best if you spoke to your healthcare provider before taking L-Theanine, as it may increase the effect of these medications and lead to more low blood pressure.

Medications for treating Bradycardia or low heart rate: L-Theanine has been reported to slow heart rate in some people. If you take medicines for Bradycardia or other heart conditions, you should speak to your healthcare provider before taking L-Theanine.

Stimulants like Caffeine and glutamate: L-Theanine is often combined with Caffeine to help reduce caffeine jitters and increase alertness. However, L-Theanine may interact with other stimuli, such as glutamate, and may reduce their effectiveness.

It’s essential to know that these are general examples of potential drug interactions and that other medications and supplements could interact with L-Theanine.

Always speak to your healthcare provider before using L-Theanine or any other dietary supplement, especially if you are taking medications or have a medical condition.


L-Theanine, a naturally found amino acid, is appeared as a reliable drug/supplement in relaxing the mind, reducing anxiety, stress, and depression, and improving quality sleep, so far, with no potential side effects. This FDA-approved drug is very safe to use.

Note: We do not give any medical advice.



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