L-theanine Dose for Anxiety Relief: A Comprehensive Guide

Navigating the stress of daily life can be challenging, and this is a shared experience among many. Formally diagnosed anxiety disorders are common, affecting an estimated one-third of people at some point in their lives. Many more may experience anxiety symptoms but not seek formal treatment. You are certainly not alone if you or a loved one have felt overwhelmed.

Many resources and strategies are available to help reduce anxiety symptoms, and natural products are a popular approach. L-theanine is touted among people for helping reduce anxiety symptoms, and some limited research suggests using an L-theanine dietary supplement for additional support may offer some mental health benefits. It's essential to make an informed choice, so let's look more closely at the research related to these potential health benefits and any potential risks that are important to discuss with your healthcare provider.

What is L-theanine?

L-theanine is an amino acid with potential health benefits for sleep quality, stress, and cognitive performance. It's not an essential amino acid, but you can obtain it by using dietary sources like green tea leaves or by taking L-theanine supplements.

Early research suggests L-theanine may help support health in numerous ways, including:

Although distinct from essential amino acids, L-theanine may impact many processes in the body, and there may be some generalized support for overall health. When it crosses the blood-brain barrier, L-theanine is suggested to enhance the effects of gamma-aminobutyric acid (GABA). This effect may help promote calm, reduce anxiety, and improve sleep latency and duration, as observed in animal studies.

L-theanine is also often paired with caffeine. The calming effect of L-theanine is thought to balance the stimulating effects of caffeine, and while the exact mechanisms behind these cognitive benefits aren’t fully understood, L-theanine's impact on glutamate, GABA, and dopamine systems may play a role.

In clinical trials for attention-deficit/hyperactivity disorder, it appeared that taking L-theanine with caffeine improved cognitive performance and increased subjective alertness. However, caffeine may make anxiety symptoms worse and contribute to difficulty sleeping, so it's important to keep an eye on the ingredients and doses included in your supplements.

What dose is recommended for anxiety relief?

There are no formal dosing recommendations for L-theanine, and preliminary research in humans used varying amounts. In a recent systematic review primarily involving clinical trials of healthy adults exposed to stressful conditions, the most common dose of L-theanine was 200–400 mg daily. Using up to 400 mg of L-theanine daily for eight weeks has been reported to be safe and has been associated with some positive effects on anxiety symptoms.

However, several factors may influence an ideal dose for each individual, including:

• Potential tolerance or lack of initial response
• Severity of anxiety
• Other health conditions or treatments

Further studies would be beneficial for better identifying patients who may be more likely to benefit from using L-theanine at particular dosages. Speaking with a healthcare professional about your specific needs and goals can help you determine whether L-theanine is appropriate and find a dose that's more likely to be safe and effective.

Benefits of L-theanine for managing anxiety

Clinical trials rely on participant responses to questionnaires like the State-Trait Anxiety Inventory (STAI) or Pittsburgh Sleep Quality Index (PSQI). Changes in these scores can help identify whether a supplement seems to have helped with perceived anxiety symptoms or improved sleep.

Some promising results have been found, such as a small study showing improvements in both STAI and PSQI after using L-theanine. This means patients reported fewer anxiety symptoms and improved sleep.

Some individuals may already use a medication for anxiety and are interested in additional support. A study published in the Journal of Psychiatric Research suggests that L-theanine did not offer additional improvement in anxiety symptoms for those already using a medication, but participants did report improvements in sleep.

Providing a broader view, a systematic review of nine clinical trials published in Plant Foods for Human Nutrition suggests 200–400 mg of L-theanine daily may improve anxiety symptoms in individuals exposed to stressful conditions. However, larger and longer-term studies are needed to help better predict how a broader population might respond.

Potential side effects

L-theanine is generally recognized as safe, and its side effects are likely mild if taken at doses between 200 and 400 mg daily. Some of the potential side effects may vary depending on the source of L-theanine, partly because of the potential for stimulants like caffeine to be included. When L-theanine is isolated, it may cause:

Talking with your healthcare providers about all your medications, including supplements, is important because they may interact with each other. For instance, L-theanine may affect blood pressure and interact with blood pressure medications. L-theanine also affects sleep, so taking it with sedatives may be unsafe.

There is a general lack of research related to the effects of L-theanine during pregnancy and breastfeeding. It's critical to talk with your doctor before starting new supplements if you are or may become pregnant.

How to choose the right L-theanine supplement

Some people supplement L-theanine by using an isolated product that only contains the amino acid as the active ingredient. Others may add L-theanine by using a product with other components, like green tea.

L-theanine supplements

If you plan on using a supplement with isolated L-theanine, talking with your healthcare provider before starting is helpful. This will help ensure it fits your overall healthcare needs and current treatments. It can also help you determine the best dose for you. If L-theanine is suitable for you, there are some helpful things to remember when choosing your supplement.

Over-the-counter products aren't evaluated directly by the Food and Drug Administration (FDA), and there has been some confirmed variability in the quality of some products. Some products may not have the same ingredients or doses reported on the label. Signs of quality include:

• GMP (Good Manufacturing Practices) commitment
• Independent third-party testing

While the FDA doesn't directly evaluate over-the-counter products, it provides manufacturing guidelines (GMP). Certifications from third-party organizations suggesting the manufacturer is committed to these standards may be a sign of quality.

It's also helpful to look for products that undergo independent third-party testing. This helps ensure the product is free of specific contaminants and that the ingredients and their strength match the label. In a sense, it helps ensure you're actually getting what you paid for.

Green tea

Because green tea is often closely associated with L-theanine, its potential for anxiety relief should also be considered. Green tea varieties like matcha have been used for many centuries for various health purposes. Green tea catechins like epigallocatechin (EGCG) are believed to be associated with many potential benefits, including improved memory and attention. However, their potential impact on anxiety symptoms is not well understood.

Aside from EGCG, matcha also contains a significant amount of caffeine. Both EGCG and caffeine may counteract some of the beneficial effects of L-theanine for anxiety, so it's important to be aware of the variability in tea components.

For instance, a study published in Nutrients found that a majority of green tea products available on the market may be unlikely to contain a ratio of L-theanine, ECGC, and caffeine that supports stress reduction.

Because higher L-theanine levels and lower caffeine and ECGC levels may be more beneficial for anxiety specifically, it may be helpful to research the contents of your tea.

Article history

Our experts strive to provide up to date information and update articles when new information becomes available

September 25, 2024

Fact checked by Gabija Dimšaitė, BSc

September 25, 2024

Updated by Matt Sommers, PharmD

June 12, 2023

Fact checked by Healthnews Research Team

June 12, 2023

Written by Jan Vincent Beltran, PhD