Reviews and Information for L-Theanine
L-Theanine Supplements
Find the best L-theanine supplement and learn what this compound (also found in green and black tea) can and cannot do for stress, sleep, and blood pressure. Also learn about L-theanine dosage, safety, side effects and potential drug interactions.
L-Theanine Supplements Review
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News Release
March 09, 2023
L-Theanine Supplements Reviewed by ConsumerLab. Top Pick Chosen.
White Plains, New York, March 9, 2023 —L-theanine supplements are often promoted to reduce stress and improve sleep and cognition.
Product Review
GABA Supplements Review
Does GABA Work As a Supplement?
News Release
August 13, 2015
Feeling Stressed? ConsumerLab.com Reviews the Evidence for L-Theanine and Test Popular Products
White Plains, New York, August 21, 2015 — L-theanine is often promoted to reduce stress, and for conditions such as ADHD — but does it really work? ConsumerLab.com recently reviewed the evidence and purchased popular brands of L-theanine to test their quality.
Clinical Update
10/05/2019
L-Theanine for Sleep and Cognition?
Several studies have evaluated whether a single dose of L-theanine (found in green tea) can reduce stress and anxiety. A new study has evaluated the effect of L-theanine when taken daily for several weeks. See the results in the What It Does section of the L-Theanine Supplements Review. Also see our top choices for L-Theanine.
Clinical Update
5/16/2023
Solgar L-Theanine Approved
Solgar L-Theanine 150 mg was recently tested and Approved through our voluntary Quality Certification Program and was added to our L-Theanine Supplements Review.
Clinical Update
10/10/2023
L-theanine for Cognition?
Does taking L-theanine (a compound that occurs naturally in tea) improve attention or cognition in healthy men and women? Find out in the What It Does section of our L-theanine Supplements Review, which includes our Top Picks for L-theanine.
Also see: Do any supplements, foods or lifestyle modifications help with brain function, like memory and cognition?
Clinical Update
1/12/2024
L-Theanine for Fatigue?
Did drinking a beverage containing L-theanine, with or without CBD, reduce fatigue? See what a recent study showed in the Stress, sleep and cognition section of our L-Theanine Review, which includes our Top Picks for L-theanine.
Also see: Which supplements help to improve energy and decrease fatigue?
CL Answer
Which supplements and lifestyle changes improve sleep, and which cause insomnia?
Find out which vitamins may help you sleep and learn if any vitamins or supplements can cause insomnia.
Clinical Update
2/08/2022
L-Theanine for Stress?
Can L-theanine supplementation reduce stress during demanding tasks? See the latest evidence in the What It Does section of our L-Theanine Supplements Review.
Clinical Update
5/21/2024
L-Theanine May Reduce Sleep
A recent study of L-theanine suggests it may significantly reduce time asleep. See the details in the What It Does section of our L-Theanine Supplements Review, which includes our Top Picks.
Product Review
CBD Oils, Softgels, Gummies, Creams & Salves Review
See How Much CBD and THC We Found in Products.
Product Review
Melatonin Supplements Review
Trouble Sleeping? See CL's Tests of Melatonin Supplements and Top Picks.
Clinical Update
2/05/2019
Theanine for Anxiety?
Theanine is promoted as an anxiety-reducing supplement, but does it really work? See results of a recent study in the What It Does section of the L-theanine Supplements Review. Also see our top choices for L-theanine supplements.
CL Answer
Which supplements can help me sleep and which cause insomnia?
Find out which supplements may improve sleep, including melatonin, L-tryptophan, and magnesium, and which may make sleeping more difficult.
CL Answer
Does Qualia Mind boost memory and mental function and is it worth cost?
Learn about the ingredients in Qualia Mind, whether or not we think the formula works and is safe, and if we think it's worth the cost.
Product Review
Weight Loss Supplements Review (7-Keto DHEA, Forskolin and Stimulant Blend Supplements)
Choose the Best Weight Loss Supplement. Be Careful With Weight Loss Supplements — Few Pass Quality Testing and Safety Review.
CL Answer
Does Alpha Brain really improve memory, focus and cognition?
Find out if Alpha Brain really improves memory, focus and cognition. See the clinical evidence and get details about Alpha Brain ingredients, as well as potential side effects and drug interactions. ConsumerLab.com's answer explains.
CL Answer
A few weeks after starting acetyl-L-carnitine, I became so sluggish I could hardly function. Could this be due to the supplement?
Find out if carnitine supplements can cause sluggishness and fatigue.
Product Review
Green Tea Review: Tea Bags, Matcha Powders, and Supplements
Some green teas provide barely any green tea polyphenols, while some others are high strength. See the Test Results and Our Top Picks for Green Tea.
CL Answer
Do any supplements help relieve stress?
Are there actually supplements for stress relief and panic attacks? Learn more about holy basil, fish oil, L-theanine, and ginseng.
Recalls & Warnings
February 17, 2022
Seller of L-Theanine, Lutein, Noopept and More Warned for Drug Claims
On February 4, 2022, the FDA issued a warning letter to Crystal Clear Supplements following a review of the company’s website and social media which found statements about Tianeptine Sodium Powder, Tianeptine Sulfate Powder, PEA Capsules, Phenibut Capsules, Synephrine Powder, Noopept ...
CL Answer
Can glycine improve sleep, reduce depression, or reduce nighttime urinary frequency?
Can glycine really help improve sleep, reduce depression, or reduce nighttime urinary frequency? Lean more about glycine and its uses and benefits.
CL Answer
I find labels on supplement bottles misleading. For example, an L-theanine label says 200 mg on the front but the back says each pill contains just 100 mg, but a serving is 2 capsules. Is this legal?
Learn more about misleading supplement labels and legality, including labels that say "formulation," "blend," or "complex."
CL Answer
What is the best way to take melatonin to get a good night's sleep?
Learn more about the best way to take melatonin for better sleep. When to take it, how to take it, and general melatonin information.
CL Answer
Which supplements help to improve energy and decrease fatigue?
Energy supplements and vitamins - Some can help increase energy and reduce fatigue, including CoQ10, curcumin/turmeric, cocoa, and B vitamins.
CL Answer
What are the best supplements for depression and anxiety?
Best natural supplements for depression and anxiety, including the evidence for fish oil, vitamin D, probiotics, and herbal supplements for depression such as curcumin (from turmeric) and saffron.
CL Answer
Can any supplements improve or worsen symptoms of fibromyalgia?
Find out if any supplements may help improve fibromyalgia symptoms, learn which supplements do not seem beneficial, and find out if any supplements worsen symptoms.
CL Answer
What are the side effects of ashwagandha supplements?
Learn about the safety and side effects of ashwagandha supplements, including headache, sleepiness, upset stomach, blood pressure and more. ConsumerLab.com's answer explains.
CL Answer
Which supplements can help to lower blood pressure?
Supplements to lower blood pressure, including CoQ10, vitamin C, fish oil, and olive oil, are all explored to find out what works.
Recalls & Warnings
January 18, 2024
FDA Warns Consumers Not to Use Neptune’s Fix Products
On November 21, 2023, the FDA warned consumers not to purchase or use Neptune’s Fix products because they contain tianeptine. The FDA has received severe adverse event reports after use of these products, including seizure and loss of consciousness.
CL Answer
Sugar Substitutes: Pros, Cons, and Best Choices
Learn about the pros and cons of using sugar substitutes and artificial sweeteners in place of table sugar. Sweeteners discussed include stevia, monk fruit, and other high-intensity sweeteners; xylitol, erythritol, allulose and other low-calorie sweeteners; and agave syrup, coconut sugar, honey, molasses and other sugar alternatives.
Recalls & Warnings
July 11, 2014
Maker of Cough and Sleep "Remedies" Warned for Drug Claims
On June 27, 2014, the FDA issued a warning letter to Zarbee's, Inc.
Recalls & Warnings
July 27, 2012
Prescription and Street Drug Alternatives Found in Male Enhancement, Mood, and Sleep Supplements
On July 10, 2012, the FDA issued a warning letter to Evol Nutrition Associates, Inc. subsequent to a 2011 inspection which found a number of the company's products contained prescription and investigational drugs and were misbranded.
Recalls & Warnings
September 10, 2012
Maker of Concussion Recovery Supplement Warned For Making Drug Claims
On August 28, 2012, the FDA issued a warning letter to Trinity Sports Group, Inc. after a review of the company's websites found statements about Neuro Impact Concussion Response Formula constituted drug claims not permitted on supplements.
Recalls & Warnings
May 30, 2015
Seller of Supplements for Herpes, Prostate Cancer & More Warned for Drug Claims
On May 7, 2015, the FDA issued a warning letter to Strictly Health Corporation, following a review of the company's websites which found statements made about FENVIR, Prosta Pep and Tonalin brand CLA to be drug claims.
Recalls & Warnings
June 12, 2014
Marketers of Memory Supplement Settle FTC Charges of Deceptive Claims
Martek Biosciences Corporation and i-Health Inc., marketers of BrainStrong Adult, have agreed to settle Federal Trade Commission (FTC) charges that claims the supplement could improve adult memory and prevent cognitive decline were deceptive, and not supported by sufficient clinical evidence.
Recalls & Warnings
December 26, 2012
Seller of Blood Sugar, Depression and Sleep Supplements Warned For Making Drug Claims
On October 15, 2012, the FDA issued a warning letter to BioNeurix Corporation after statements found on the company's website, http://www.pharma-tree.com, were found to promote the dietary supplements Blood Sugar 360, Amoryn, Seredyn, and Mellodyn as drugs.
Recalls & Warnings
March 15, 2013
Maker of Liquid Supplements Warned For Manufacturing Violations and Drug Claims
On January 31, 2013, the FDA issued a warning letter to Liquid Health, Inc.
