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L-Theanine Supplements Review

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

Latest Update
L-theanine for Cognition?
Tod Cooperman, M.D.
Medically reviewed and edited by Tod Cooperman, M.D.
 
Updated October 10, 2023 ⓘ Published March 02, 2023

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).

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.