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L-Theanine Supplements Review

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

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).

+&#; 17 sources

In addition the results of its expert testing, ConsumerLab uses only high-quality, evidence based, information sources. These sources include peer-reviewed studies and information from agencies such as the FDA and USDA, and the National Academy of Medicine. On evolving topics, studies from pre-print journals may be sourced. All of our content is reviewed by medical doctors and doctoral-level experts in pharmacology, toxicology, and chemistry. We continually update and medically review our information to keep our content trustworthy, accurate, and reliable. The following sources are referenced in this article:

• Kimura, Biol Psychol
• Lu, Hum Psychopharmacol Clin Exp
• Evans, Neurol Ther
• Moulin, Neurol Ther
• Hidese, Nutrients
• Ramani, BBI &#; Integrative
• Dassanayake, Nutr Neurosci
• Lyon, Altern Med Rev
• Sarris, J Psychiatr Res
• Ritsner, J Clin Psychiatry
• Rogers, Psychopharmacology
• Sugiyama, Cancer Lett
• Keenan, Food Chem
• Nobre, Asia Pac Clin Nutr
• Scheid, J Nutrition
• Haskell, Biol Psychol
• Heese, AANA J

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

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Doctor's Best L-Theanine with Suntheanine

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Fit Powders L-Theanine

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GNC L-Theanine

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Healthy Origins L-Theanine

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Jarrow Formulas L-Theanine 200

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Life Extension Theanine XR Stress Relief

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Nature's Trove L-Theanine 200 mg

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Solgar L-Theanine 150 mg

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Sports Research [SR] L-Theanine

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Swanson L-Theanine

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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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L-theanine may have benefits for depression, sleep, and stress. It has antioxidant and anti-inflammatory properties, as well as regulatory effects on anxiety and the immune system.

L-theanine is a non-protein amino acid found in the tea plants Camellia sinensis L., from which green and black tea are made. It's the main source of flavor in tea and has a caramel-like taste that reduces the bitter flavor of tea leaves. You can also take L-theanine as a dietary supplement.

1. Can Reduce Stress and Anxiety

Supplementation with 200-400 milligrams of L-theanine per day may reduce stress and anxiety in people exposed to stressful situations. L-theanine acts on the central nervous system. It influences certain pathways and receptors in the brain to reduce stress and anxiety.

L-theanine specifically reduces the release of glutamate. This excitatory neurotransmitter triggers nerve signals. High levels of glutamate can cause hyperactive nerve signals during times of stress and anxiety.

L-theanine increases the release of γ-aminobutyric acid (GABA), an inhibitory neurotransmitter that blocks nerve signals. GABA is thought to regulate anxiety, especially in people with anxiety disorders. L-theanine can also increase dopamine levels to improve mood and increase alpha-frequency brain waves. This pattern of brain activity is associated with relaxation.

2. Has Been Shown To Support Cancer Treatment

Research has shown that L-theanine may enhance the efficacy of doxorubicin. This chemotherapy drug helps treat cancer. Animal studies have found that L-theanine can help more of the drug enter cancer cells and get rid of them. These results are promising, but more research is needed to know if L-theanine has the same effect on human cancer cells.

3. Helps Improve Immune Function

Some evidence suggests that L-theanine can support the immune system. One review noted that L-theanine may reduce the number of upper respiratory infections, such as a cold and the flu. L-theanine has been shown to help immune cells respond to bacteria and viruses, which allows your body to fight off an infection.

4. Supports Restful Sleep

L-theanine may improve sleep quality due to its relaxing effects on the nervous system. A small study examined 30 participants who took 200 milligrams of L-theanine daily for four weeks. The participants had reduced sleep latency, or the time it takes to fall asleep. They also had less sleep disturbance and use of sleep medication compared to those who took a placebo.

A study of 160 people tested the effects of various supplements, including L-theanine, on sleep. Supplementing with 200 milligrams of L-theanine for seven days significantly improved sleep problems like trouble falling and staying asleep.

Are you interested in learning more about L-Theanine Powder? Contact us today to secure an expert consultation!

5. May Boost Cognitive Performance

Some evidence suggests that L-theanine may benefit memory and attention. Supplements can improve the brain's ability to focus and remember information. One study looked at 69 Japanese adults aged 50-69 years old who took 100.6 milligrams of L-theanine. A single dose improved reaction time and working memory on cognitive tests.

L-theanine may protect brain cells from age-related damage and reduce the risk of cognitive disorders like Parkinson's disease. The high content of L-theanine in green tea is thought to lower the risk of dementia.

6. Might Improve Depressive Symptoms

L-theanine may reduce depression symptoms. It can modulate the activity of neurotransmitters like dopamine. A small study found that 250 milligrams of L-theanine for eight weeks significantly reduced symptoms of depression and anxiety.

L-theanine may also positively affect symptoms of other mental health disorders like schizophrenia and schizoaffective disorder. These findings are encouraging, but it's important to discuss supplement use to treat mental health disorders with a healthcare provider.

How To Take

L-theanine is available in several forms, including pills, liquids, capsules, and powders. You can also get L-theanine by drinking certain green or black teas.

You can take L-theanine on its own or in combination with other calming substances. L-theanine is often combined with magnesium. This mineral is thought to help regulate stress.

You may take L-theanine at any time of day. Taking L-theanine in the morning can support a healthy stress response. You might take it at night before bedtime to promote restful sleep.

Dosage 

Dosing of L-theanine for anxiety, sleep, and other health goals varies. Most studies have used doses that range from 100-400 milligrams per day. People have safely used higher doses of L-theanine without adverse side effects.

The amount of L-theanine found in teas may depend on when and where the tea is sourced and how it's brewed. Green, black, white, and oolong teas typically contain about 5-7 milligrams of L-theanine per gram.

Is L-Theanine Safe?

L-theanine has been shown to be safe, even when taken in high doses. It's generally well-tolerated and not associated with health risks or side effects.

L-theanine may not be safe for people who are pregnant or breastfeeding. L-theanine can lower blood pressure levels, so it could be unsafe in people with hypotension (low blood pressure).

Drinking high amounts of caffeinated teas that contain L-theanine may cause side effects like headache, dizziness, and rapid heartbeat. Most people can safely consume about 400 milligrams of caffeine per day.

Potential Drug Interactions

Talk to a healthcare provider before starting a new supplement, especially if you take one or more medications. L-theanine supplements may lower blood pressure. You may want to avoid L-theanine if you take one or more medications to lower blood pressure.

Due to its soothing effects, L-theanine may also have an additive effect with some sedative medications. Avoid taking supplements that contain D-theanine. D-theanine may prevent the absorption of L-theanine in the body.

What To Look For

It's important to choose supplements you can easily tolerate. If you have difficulty swallowing pills, you may want to purchase a liquid or powder L-theanine supplement.

Can You Take Too Much?

L-theanine is not known to be toxic and has not been shown to have adverse side effects on health, even when taken in high doses. It's still best to follow the dosage instructions listed on the product.

Drinking more than 400 milligrams of caffeine per day may cause side effects if you are drinking teas that contain L-theanine. One 8-ounce cup of tea may contain 14-60 milligrams of caffeine.

Side Effects of L-Theanine

L-theanine supplements have not been associated with any side effects. Drinking large amounts of caffeinated teas that contain L-theanine can lead to symptoms like:

• Anxiety
• Dehydration
• Dizziness
• Drowsiness
• Fast heart rate
• Headaches
• Insomnia
• Restlessness
• Shakiness
  

A Quick Review

L-theanine is an amino acid concentrated in tea and can be a dietary supplement. It has calming effects on the body and may reduce stress and relieve symptoms of anxiety and depression.

L-theanine supplements are considered safe and are not associated with any side effects. Talking to a healthcare provider before starting a new supplement is important to ensure it's safe and appropriate for you.

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