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Cognition / Stress

L-Theanine · L-Theanine

The 'calm alertness' amino acid from green tea.

B
Evidence grade
Human RCTs, biomarker outcomes
Strongest study
Tier 1 · 1 linked study

Short answer

Excellent 'daily-driver' calm/focus supplement. Take with morning coffee.

Product and dose overview

L-Theanine (L-Theanine) is a cognition / stress with evidence grade B, meaning it is supported by human RCTs. We track 8 products containing L-Theanine. Typical doses range from 50 to 400 mg per serving. The top-ranked product scores 7.7 out of 10 on our composite scale (dose, evidence, price, testing, transparency). Prices range up to $69.00 per month.

Evidence grade: B Products in database: 8 Category: Cognition / Stress

Top L-Theanine products

ProductBrandDosePrice/mo3rd-party testedScore
SureSleepDoNotAge400 mg$45.00Yes7.7
L-Theanine SupplementDouble Wood Supplements200 mg$19.95Yes7.7
L-Theanine CapsulesNootropics Depot200 mg$15.99Yes7.7
Daily Longevity BlendAgeMate100 mg$69.00Yes7.0
Longevity Mix - Blood OrangeBlueprint200 mg$49.00Yes6.7

Scores are editorial judgments, not a scientific standard. See 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

Trial dose
200 mg
/ day
Range in trials
100 to 400 mg
/ day
Common forms
Capsule, Powder, Combined with caffeine

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.

Regulatory status

EUFood supplement
USGRAS
UKFood supplement
CANHP

Timeline

Regulatory events, evidence grade changes, and key research milestones for L-Theanine, most recent first. Studies link to the paper; regulatory entries name and link the responsible authority.

  • 2025-04 Regulatory single source
    EU Court sharpens the bar for botanical health claims
    A 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.
  • 2024-06 Regulatory confirmed
    EU report identifies 117 supplement substances as potential health risks
    The 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.
    Source →
  • 2020 Research milestone
    Williams et al. 2020
    L-theanine reduces stress and improves sleep quality in RCTs.
    Source →
  • 2006-12 Regulatory confirmed
    EU Health Claims Regulation adopted
    Regulation (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.
    Source →
  • 1997 Regulatory confirmed
    EU introduces the Novel Food Regulation
    Regulation (EC) No 258/97 required any food or food ingredient without a history of consumption in the EU before 15 May 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.
    Source →
2026 evidence refresh

L-theanine has modest but real evidence for sleep quality and acute attention, while a 2025 meta-analysis 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.

Human RCT base
19
peer-reviewed randomised trials
Largest single trial
n = 897
A 2025 systematic review and meta-analysis pooling 18 RCTs and 897 participants found L-theanine significantly improved subjective sleep onset latency, daytime dysfunction, and overall sleep quality versus placebo. source

Best-supported claim

L-theanine's most consistent evidence is for subjective sleep quality. A 2025 meta-analysis 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 systematic review and meta-analysis 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

Safety

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

  • May 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

  • The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
    Sleep Medicine Reviews / related sleep journal 2025 · n = 897

    Meta-analysis of 18 RCTs found L-theanine significantly improved subjective sleep onset latency, daytime dysfunction, and overall sleep quality.

    Read study →
  • Promising, but Not Completely Conclusive-The Effect of L-Theanine on Cognitive Performance: A Systematic Review and Meta-Analysis
    Journal of clinical medicine 2025 · n = 148

    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.

    Read study →
  • Cognitive and affective effects of L-Theanine: a systematic review
    Molecular psychiatry 2026 · n = n/a

    Systematic review of L-theanine's cognitive and mood effects concludes findings remain mixed and dependent on test type and dosing protocol.

    Read study →

Landmark studies

Found in these products (8)

All products in our catalog that contain L-Theanine, ranked by our overall score. Ranking is editorial, never paid.

DoNotAge
SureSleep
Adaptogen
Ingredients listed
4 ingredients listedlargest listed: L-Tryptophan 1,000 mg
Price per serving
$1.50$45.00 · 30 servings
Testing
3rd-party listed · public lab certificate

Elemental vs compound: check label

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 7.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$1.73
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with donotage.org
Double Wood Supplements
L-Theanine Supplement
Cognition
Active per serving
L-Theanine 200 mgCapsule · 120 servings
Price per serving
$0.17$19.95 · 120 servings
Testing
3rd-party listed · public lab certificate

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 7.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$0.17
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with doublewoodsupplements.com
Nootropics Depot
L-Theanine Capsules
Cognition
Active per serving
L-Theanine 200 mgCapsule · 30 servings
Price per serving
$0.53$15.99 · 30 servings
Testing
3rd-party listed · public lab certificate

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 7.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$0.53
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with nootropicsdepot.com
Longevity stack
Ingredients listed
8 ingredients listedlargest listed: Glycine 700 mg
Price per serving
$2.30$69.00 · 30 servings
Testing
3rd-party listed · no public lab certificate

Multi-ingredient bundle

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 7.0/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$1.38
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with agemate.com
Longevity stack
Ingredients listed
6 ingredients listedlargest listed: Creatine 2,500 mg
Price per serving
$1.63$49.00 · 30 servings
Testing
3rd-party listed · no public lab certificate

Multi-ingredient bundle

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 6.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

83%
of trial dose
$3.27
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with blueprint.bryanjohnson.com
AG1 (Athletic Greens)
AGZ: Nightly Sleep Support
Adaptogen
Ingredients listed
8 ingredients listedlargest listed: Glycine 2,000 mg
Price per serving
$3.30$99.00 · 30 servings
Testing
3rd-party listed · no public lab certificate

Elemental vs compound: check label

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 6.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$3.96
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with drinkag1.com
NOVOS Labs
NOVOS Core
Longevity stack
Ingredients listed
12 ingredients listedlargest listed: Glycine 1,000 mg
Price per serving
$2.97$89.00 · 30 servings
Testing
3rd-party listed · no public lab certificate

Multi-ingredient bundle

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 6.3/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

50%
of trial dose
$14.83
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with novoslabs.com
Longevity stack
Ingredients listed
7 ingredients listedlargest listed: NMN 250 mg
Price per serving
$1.97$59.00 · 30 servings
Testing
3rd-party listed · no public lab certificate

Multi-ingredient bundle

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 5.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$3.93
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with perpetualife.bio
Editorial guides

Buying guides and comparisons

Neighbouring molecules

Related ingredients

See all in Cognition / Stress →

Molecules in the same class, plus the actives most often formulated alongside L-Theanine in our catalogue.

GlycineBstacked together in 4 productsMagnesiumAstacked together in 3 productsHyaluronic AcidBstacked together in 3 productsResveratrolCstacked together in 2 productsSpermidineCstacked together in 2 productsCa-AKGDstacked together in 2 productsFisetinCstacked together in 2 productsL-TryptophanBstacked together in 1 product
Product shelves
See all in Longevity stack (4)See all in Adaptogen (2)See all in Cognition (2)

See L-Theanine in context: the mechanism it acts through, the biomarker it moves, the products that dose it, and the trials that tested it.

View L-Theanine on the Longevity Map →

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 day, with a range of 100 to 400 mg per day. 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 products containing L-Theanine. The top-ranked product scores 7.7 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.

Independently checked

Data verification

Evidence grade
B
Human RCTs, biomarker outcomes
Research dose
200 mg
Products tracked
8
Updated continuously
Safety signal
Very safe. Suntheanine® is the branded form with the most...

Evidence grades are reviewed when new human RCTs are published. Product counts update automatically as new products are added. Dose ranges reflect published trial data, not brand recommendations. Read how we verify.