L-Theanine · L-Theanine
The 'calm alertness' amino acid from green tea.
Short answer
L-Theanine (L-Theanine) is a cognition / stress with evidence grade B, meaning it is supported by human RCTs. We track 8 produkter containing L-Theanine. Typical doses range from 50 to 400 mg per portion. The top-ranked product scores 8.2 out of 10 on our composite scale (dose, evidence, price, testing, transparency). Prices range up to $99.00 per månad.
Top L-Theanine produkter
| Product | Varumärke | Dose | Pris/mo | 3rd-party tested | Poäng |
|---|---|---|---|---|---|
| L-Theanine Supplement | 200.0 mg | $19.95 | Yes | 8.2 | |
| L-Theanine Capsules | 200.0 mg | $15.99 | Yes | 8.2 | |
| SureSleep | 400 mg | $45.00 | Yes | 7.5 | |
| Longevity Mix - Blood Orange | 200 mg | $49.00 | Yes | 6.5 | |
| AGZ: Nightly Sleep Support | 200 mg | $99.00 | Yes | 6.5 |
Scores are editorial judgments, not a scientific standard. Se how we score.
What it is
An amino acid uniquely found in tea. It crosses into the brain and increases alpha-wave activity, the state of relaxed focus. Works well with caffeine to smooth out jitters.
Why people take it
Small trials show reduced stress response, improved attention, and better sleep quality. Effect size is real but modest. Combined with caffeine (typically 100 mg + 200 mg L-theanine), it's a well-studied nootropic pairing.
Our verdict
Excellent 'daily-driver' calm/focus supplement. Take with morning coffee.
Structure & class
γ-Glutamylethylamide. Non-proteinogenic amino acid. Crosses BBB, increases alpha waves at 8 to 10 Hz.
Mechanism & clinical data
Meta-analyses (Williams 2020) confirm anxiolytic effects at 200 to 400 mg. Combination with caffeine improves attention beyond either alone (Owen 2008).
Pharmacokinetics
~1 hour.
Dose & forms
What to watch out for
Very safe. Suntheanine® is the branded form with the most published data.
Where this dose comes from
The trial dose above is our editorial pick from the published human trials for this ingredient. We choose the dose that the best-available studies used on the endpoint most relevant to longevity. The range shows the lowest and highest doses tested in published trials. The landmark studies below are the papers we read to set it. You can click through and check our work.
When new trials publish, our automated sweeps flag them. If a new study materially changes the dose, we update it through editorial review and record the old dose, new dose, and the triggering study in every affected product's recommendation history. The dose is never changed automatically.
Regelverk status
Timeline
Regelverk events, evidence grade changes, and key research milestones for L-Theanine, most recent first. Every entry links to its primär source.
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EU Court sharpens the bar for botanical health claimsA Court of Justice of the European Union ruling in april 2025 further tightened the requirements for how botanical ingredients (herbs, plant extracts) can be marketed with health claims in the EU, effectively removing much of the flexibility of the on-hold list.
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EU report identifies 117 supplement substances as potential health risksThe HoA Working Group on Food Supplements (26 European countries) published its first report evaluating 117 substances used in food supplements. Of these, 65 were assessed as likely novel foods, 6 were already regulated, 34 had insufficient data, and 12 were prioritized for Article 8 restriction under Regulation (EC) No 1925/2006. The 12 priority substances include ashwagandha, curcumin, melatonin, piperine, St. John's wort, coumarin, p-synephrine, maca, holy basil, Melaleuca, black cohosh, and L-tryptophan. The report drew on 1,500 RASFF alerts reviewed between 2017 and mid-2022.
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EU Health Claims Regulation adoptedRegulation (EC) No 1924/2006 laid down harmonised rules for nutrition and health claims made on foods, including supplements. Only claims listed in the EU Register of authorised claims can be used. Rejected botanical claims are held in a separate on-hold list.
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EU introduces the Novel Food RegulationRegulation (EC) No 258/97 required any food or food ingredient without a history of consumption in the EU before 15 maj 1997 to be authorised before being placed on the market. This is the framework that captures NMN, spermidine as a supplement ingredient, urolithin A, and many other longevity actives.
L-theanine has modest but real evidence for sleep quality and acute attention, while a 2025 metaanalys of only 5 RCTs found its broader cognitive benefits could not be confirmed across most test methods.
Verified 2026-07-07. We update this section as new peer-reviewed trials land.
Best-supported claim
L-theanine's most consistent evidence is for subjective sleep quality. A 2025 metaanalys of 18 RCTs and 897 participants found significant improvements in sleep onset latency (SMD 0.15), daytime dysfunction (SMD 0.33), and overall sleep quality score (SMD 0.43) versus placebo (https://pubmed.ncbi.nlm.nih.gov/40056718/). A 30-person crossover RCT by Hidese et al. found 200 mg/day for 4 weeks significantly reduced depression and trait anxiety scores and improved several Pittsburgh Sleep Quality Index subscales versus placebo (https://pmc.ncbi.nlm.nih.gov/articles/PMC6836118/).
Not supported by the evidence base
L-theanine is marketed as a reliable cognitive enhancer that sharpens focus and attention on its own, but a 2025 systematisk översikt and metaanalys of only 5 RCTs and 148 healthy adults found the beneficial effects on cognitive performance could not be confirmed across most test methods, with only rapid visual information processing showing a dose-dependent effect while simple reaction time and Stroop test performance showed no significant change (https://pubmed.ncbi.nlm.nih.gov/41227106/). A 50-person, 12-week RCT similarly found no significant effect on MMSE-J scores or most Cognitrax domains after chronic dosing, with benefits limited to a single acute dose on attention and working memory tasks (https://pmc.ncbi.nlm.nih.gov/articles/PMC8080935/).
Typical dose
100-200 mg/day, taken once daily or split into two doses
Säkerhet
L-theanine has shown no significant adverse events in RCTs up to 200 mg/day for 4 weeks, with 100% compliance and no dropouts reported in one crossover trial (https://pmc.ncbi.nlm.nih.gov/articles/PMC6836118/). It is generally recognized as safe at typical doses and is naturally present in tea. No major toxicity signals have emerged in human trials to date. Data in pregnant or breastfeeding populations, and at doses above 400 mg/day, remain limited, so caution is warranted outside studied ranges.
Interactions worth flagging
- maj have additive calming or blood-pressure-lowering effects with sedatives or antihypertensive medications
- Could theoretically enhance the effects of stimulant medications when combined with caffeine, a common pairing in supplements
Three recent studies to know
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The effects of L-theanine consumption on sleep outcomes: A systematisk översikt and metaanalys
Meta-analysis of 18 RCTs found L-theanine significantly improved subjective sleep onset latency, daytime dysfunction, and overall sleep quality.
Läs studie → -
Promising, but Not Completely Conclusive-The Effect of L-Theanine on Cognitive Performance: A Systematic Review and Meta-Analysis
Meta-analysis of 5 RCTs found L-theanine's cognitive benefits could not be confirmed across most test methods, with only rapid visual processing showing a dose-dependent effect.
Läs studie → -
Cognitive and affective effects of L-Theanine: a systematisk översikt
Systematic review of L-theanine's cognitive and mood effects concludes findings remain mixed and dependent on test type and dosing protocol.
Läs studie →
Landmark studies
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Williams et al. 2020
L-theanine reduces stress and improves sleep quality in RCTs.
Läs studie →
Found in these produkter (8)
Alla produkter in our catalog that contain L-Theanine, ranked by our overall score. Ranking is editorial, never paid.
Buying guides and comparisons
Related ingredients
Se alla in Cognition / Stress →Molekyler in the same class, plus the actives most often formulated alongside L-Theanine in our catalogue.
Frequently asked questions
What is L-Theanine?
An amino acid uniquely found in tea. It crosses into the brain and increases alpha-wave activity, the state of relaxed focus. Works well with caffeine to smooth out jitters.
What dose of L-Theanine should I take?
The trial dose in published human studies is 200 mg per dag, with a range of 100 to 400 mg per dag. Always consult a qualified clinician before starting any supplement.
Is L-Theanine safe?
Very safe. Suntheanine® is the branded form with the most published data.
What is the best L-Theanine supplement?
We track 8 produkter containing L-Theanine. The top-ranked product scores 8.2 out of 10 on our composite scale, which evaluates dose, evidence, price, third-party testing, and transparency. See the comparison table above. Scores are editorial judgments, not a scientific standard.
What is the evidence grade for L-Theanine?
L-Theanine has evidence grade B, meaning it is supported by human RCTs. Grade A means replicated human RCTs with hard endpoints. Grade B means human RCTs with biomarker outcomes. Grade C means mixed or small human trials. See our evidence grading methodology.
Data verification
Bevisning grades are reviewed when new human RCTs are published. Product counts update automatically as new produkter are added. Dose ranges reflect published trial data, not brand recommendations. Read how we verify.