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L-Theanine Supplements Review

Touted for Stress Relief, Do L-Theanine Supplements Work?

Latest Update
L-Theanine May Reduce Sleep
Tod Cooperman, M.D.

Medically reviewed and edited by Tod Cooperman, M.D.

 
Updated May 20, 2024 ⓘ

Summary

  • What is L-theanine?

    Often just called theanine, L-theanine, is a water-soluble amino acid found in black and green tea (see What It Is).

  • What are the health benefits of L-theanine?

    Some small clinical studies (funded by manufacturers of L-theanine) have found L-theanine may reduce stress, anxiety and blood pressure in stressful situations, but not all studies have found a benefit (see What It Does).

  • How much L-theanine should I take?

    L-theanine is typically taken at a dose of 200 mg to 400 mg per day (see Dosage).

  • Top Pick for L-theanine:

    ConsumerLab.com did not find problems with the quality of selected L-theanine products sold in the U.S., but did find large differences in the cost to obtain a 200-mg dose of L-theanine, which ranged from just 2 cents to as much as 50 cents (see What CL Found). ConsumerLab selected a Top Pick based on dose, cost, and formulation.

  • L-theanine safety and side effects:

    At typical doses, L-theanine appears to be generally safe, but there are possible interactions with blood pressure medications and benzodiazepines (see Concerns and Cautions).
Products tested in 2023

Make sure you're choosing the best L-theanine supplements approved in our tests!

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Alphabetical list of L-theanine supplement brands compared in this review

View Larger Image 8150_large_DoctorsBest-Theanine-2023.png

Doctor's Best L-Theanine with Suntheanine

View Larger Image 8151_large_FitPowders-Theanine-2023.png

Fit Powders L-Theanine

View Larger Image 8159_large_GNC-Theanine-2023.png

GNC L-Theanine

View Larger Image 8152_large_HealthyOrigins-Theanine-2023.png

Healthy Origins L-Theanine

View Larger Image 8153_large_JarrowFormulas-Theanine-2023.png

Jarrow Formulas L-Theanine 200

View Larger Image 8154_large_LifeExtension-Theanine-2023.png

Life Extension Theanine XR Stress Relief

View Larger Image 8155_large_NaturesTrove-Theanine-2023.png

Nature's Trove L-Theanine 200 mg

View Larger Image 8251_large_Solgar-LTheanine-2023.png

Solgar L-Theanine 150 mg

View Larger Image 8156_large_SR-Theanine-2023.png

Sports Research [SR] L-Theanine

View Larger Image 8157_large_Swanson-Theanine-2023.png

Swanson L-Theanine

View Larger Image 8158_large_Vitacost-Theanine-2023.png

Vitacost L-Theanine

You must join to see the full review and test results for L-theanine supplements along with ConsumerLab.com recommendations and quality ratings. You'll get test results and quality ratings for 9 supplements selected for review by ConsumerLab.com, plus 2 others which passed the same testing through ConsumerLab.com's voluntary, Quality Certification Program. Plus, you'll learn:


  • Which L-theanine supplements failed ConsumerLab testing and which passed
  • ConsumerLab's Top Pick among L-theanine supplements based on quality and value
  • Differences in the marketed forms of L-theanine, such as Suntheanine, L-Tea Active, and Theanine XR
  • The clinical evidence for and against L-theanine supplementation for reducing stress and anxiety, lowering blood pressure, and improving sleep, mood and cognition
  • Potential side effects and drug interactions of L-theanine supplements
  • Tips for buying and using L-theanine, and more!

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Additional Information
Tested through CL's Quality Certification Program prior to, or after initial posting of this Product Review.