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L-Theanine Supplements Review
Touted for Stress Relief, Do L-Theanine Supplements Work?
Products tested in 2023
Summary
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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). 
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 and How Products Were Evaluated). 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
Doctor's Best L-Theanine with Suntheanine
Fit Powders L-Theanine
GNC L-Theanine
Healthy Origins L-Theanine
Jarrow Formulas L-Theanine 200
Life Extension Theanine XR Stress Relief
Nature's Trove L-Theanine 200 mg
Solgar L-Theanine 150 mg
Sports Research [SR] L-Theanine
Swanson L-Theanine
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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Related CL Answers (7)
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Additional Information
Tested through CL's Quality Certification Program prior to, or after initial posting of this Product Review.
