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Theanine

L-Theanine is one of the main active ingredients found in green tea, alongside caffeine and green tea catechins. It helps promote relaxation without drowsiness, making it synergistic with caffeine.

Our evidence-based analysis on theanine features 66 unique references to scientific papers.

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Summary of Theanine

Primary information, health benefits, side effects, usage, and other important details

L-Theanine is an amino acid that is not common in the diet (not one of the essential amino acids or even one of the common nonessential amino acids), and is deemed a nondietary amino acid similar to L-Ornithine or L-Citrulline. L-Theanine has structural similarity to glutamine and both neurotransmitters that are produced from it (GABA and glutamate) and is known to reach the brain and act in the brain following oral ingestion.

The properties of L-theanine can be summed up as being a relaxing agent without sedation (relative to something like lemon balm which relaxes but may also sedate), and is also implicated in reducing the perception of stress and slightly improving attention. While L-theanine does not appear to induce sleep, it may (quite weakly) help with sleep although its potency suggests it may not be a good first line treatment for this.

Interestingly, the relaxing and attention promoting properties of L-theanine coupled with the lack of sedation may have its most significant supplemental role in attenuating the 'edge' of many stimulants. A combination of L-Theanine with caffeine (200mg each) is noted to be synergistic in promoting cognition and attention.

L-Theanine, for the most part, is a relaxing but not sedating amino acid that is synergistic with stimulants such as caffeine as it can 'take the edge off'. It is effective by itself in the standard supplemental dosages as well, and although it can be attained via a diet high in green tea ingestion that is the only dietary source of L-Theanine

There are some health benefits associated with green and black tea ingestion that are thought to be more reflective of the Theanine content rather than the green tea catechins or the theaflavins, and this is thought to be related to cardiovascular health (as L-Theanine positively regulates nitric oxide) and some cognitive benefits.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

L-Theanine tends to be taken in the dosage of 100-200mg, usually alongside caffeine

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Human Effect Matrix

Unlocked for Examine members

The Human Effect Matrix summarizes human studies to tell you what effects Theanine has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Notable Very High See all 3 studies
A notable increase in relaxation (usually without sedation) appears to occur, as assessed by neural measurements (such as alpha-waves) or self-report surveys. Occurs within 30 minutes to an hour
grade-b Minor Moderate See all 5 studies
Possible anxiety reducing effects, although anticipatory anxiety appears to be unaffected.
grade-c Notable - See study
A single study that used 200 mg of Suntheanine® observed a notable improvement in attentional task performance in subjects with high anxiety, whereas subjects with low anxiety didn't see a notable improvement.
grade-c Minor - See study
Sleep quality has been noted to improve in persons with hyperactivity during sleep (such as ADHD). Sleep duration and latency do not appear to be affected
grade-c Minor - See study
Activation and anxiety symptoms of schizophrenia appear to be reduced with high dose (400mg) Theanine
grade-c - - See 2 studies
grade-c - - See study
grade-c - - See study
grade-c - - See study
grade-c - - See study
No significant influence on subjective well being and mood state per se
grade-d - - See study
grade-d - - See study

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Things to Note

Primary Function:

Also Known As

L-Theanine, 5-N-Ethyl-Glutamine, γ-glutamylethylamide

Goes Well With

  • Theanine is relaxing, but does not appear to induce sedation (cause sleep)

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Click here to see all 66 references.