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Last Updated: 05/12/2020 |
L-Theanine Supplements reviewed by

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


Bluebonnet L-Theanine


Country Life L-Theanine


GNC L-Theanine


Jarrow Formulas L-Theanine 200


Life Extension L-Theanine


NOW L-Theanine Double Strength


Puritan's Pride L-Theanine


Solgar L-Theanine


Source Naturals L-Theanine


Swanson Ultra Suntheanine


Thorne Research Theanine


TwinLab L-Theanine Dots

Vitamin World L-Theanine

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  • 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).
  • L-theanine safety and side effects: At these doses, it appears to be generally safe, but there are possible interactions with blood pressure medications and benzodiazepines (See Concerns and Cautions).
  • Best value for L-theanine: 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 L-theanine. The least expensive, Approved product cost 22 cents to obtain 200 mg of L-theanine while the cost was often 60 cents for other products (See What CL Found).

You must join to see the full review and test results for L-theanine supplements along with recommendations and quality ratings. You'll get test results and quality ratings for 8 supplements selected for review by, plus 4 others which passed the same tests through's voluntary, Quality Certification Program. Plus, you'll learn:
  • Which L-theanine supplements failed testing and which passed
  • Differences in the marketed forms of L-theanine
  • The best L-theanine supplements at the lowest cost
  • The dosage of L-theanine taken for different applications and the related clinical evidence
  • Potential side effects and drug interactions of L-theanine supplements
  • Tips for buying and using L-theanine, and more!

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