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L-Theanine 150 mg

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4.7
★ ★ ★ ★ ★
(7337 ratings)
Theanine 150 mg
Product Image
Score82
A balanced 150 mg serving offers flexible daytime or evening relaxation support. Generic sourcing and limited formulation breadth are the main trade-offs.
How scoring works
Quantity:90 Veggie Cap(s) • (90 servings)
Goals:
Stress Relief
Cognitive Support
Sleep Support
Mental Focus
Mood Support
Productivity Boost
Brain Health

Score 82

A balanced 150 mg serving offers flexible daytime or evening relaxation support. Generic sourcing and limited formulation breadth are the main trade-offs.
How scoring works
$21.99($0.24 per serving)
Walmart
$ 21.99
Amazon
$ 22.99
iHerb
$ 22.99
Pure Formulas
$ 38.43
Vitacost
$ 25.29
Report prices

Analysis

A 150 mg L-theanine capsule provides a balanced amount for calm attention and relaxation. The single-active design is easy to assess and sits between common starting and higher-dose options.

It fits situational stress and pre-sleep mental tension while remaining suitable for daytime use. The product offers no direct alertness, memory, circadian, or broader mood pathway.

One capsule per serving, a long supply, and strong active efficiency support regular use. No branded source, purity claim, or inactive-ingredient detail is supplied.

Who is it for
  • Adults wanting a mid-range theanine amount
  • People seeking calm daytime focus
  • Users who value a long one-capsule supply
Best for
  • Situational stress relief
  • Calm attention
  • Mental relaxation before bed

Pros

  • Balanced 150 mg amount
  • One capsule per serving
  • Long 90-serving supply
  • Strong active efficiency

Cons

  • Generic source
  • Inactive ingredients were not supplied
  • No complementary focus or sleep active

Nutrient quality

92 Highest impact

L-theanine is a defined amino acid, although no branded source or purity marker is supplied. The L-theanine amount is meaningful for daily calming support.

.

Ingredient transparency

81 Highest impact

Every supplied active ingredient has a specific amount. No proprietary blend hides a meaningful active dose.

.

Customer satisfaction

66 High impact

The supplied aggregate rating is strong, although no specific comments are included. The large rating count makes the aggregate result relatively stable.

.

Value for money

86 Highest impact

Formula quality provides strong support for the product positioning. Dose-adjusted serving value appears reasonable, while the formula avoids obvious low-value padding.

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Report analysis

Goals

Stress Relief
Stress Relief
Impact
Highest effect
A Goal FitA Strength of SupportC+ CoverageA+ Formula Quality
Theanine · 150 mg

L-theanine directly supports calm attention without relying on sedation. Its narrow focus suits acute mental tension, though it does not add mineral or adaptogenic support.

The clearly disclosed amount fits a well-supported range and is easy to assess. A generic source limits purity assurance, but the single-active formula avoids dilution and conflicting ingredients.

Study evidence
Theanine Supportive 16 studies
Cognitive Support
Cognitive Support
Impact
Highest effect
B+ Goal FitA Strength of SupportC- CoverageA+ Formula Quality
Theanine · 150 mg

L-theanine provides well-aligned non-stimulant support for calm attention and stress-related distraction. Human evidence is useful for selected focus outcomes, though effects can be modest when it is used alone.

The 150 mg amount is appropriate and fully disclosed in a simple capsule. Missing source, purity, and testing details are the main quality limitations.

Study evidence
Theanine Supportive 25 studies
Sleep Support
Sleep Support
Impact
Highest effect
B+ Goal FitA Strength of SupportC CoverageA+ Formula Quality
Theanine · 150 mg

L-theanine supports mental relaxation without acting as a heavy sedative, which may help when a racing mind delays sleep. It does not directly regulate the circadian rhythm or provide overnight sleep-maintenance support.

The 150 mg amount sits in a useful relaxation range and is clearly disclosed as a standalone active. Lack of a branded source or purity claim leaves ingredient quality less fully documented.

Study evidence
Theanine Supportive 8 studies
Mental Focus
Mental Focus
Impact
Highest effect
B+ Goal FitA Strength of SupportC- CoverageA+ Formula Quality
Theanine · 150 mg

L-theanine provides a well-aligned amount for calm attention without adding a stimulant. The clearly identified L-isomer supports a focused, transparent formula.

Human evidence is strongest when theanine is paired with caffeine, so standalone effects may be subtle. The simple design offers good depth for stress-related distraction but limited pathway breadth.

Study evidence
Theanine Supportive 19 studies
Mood Support
Mood Support
Impact
Highest effect
B+ Goal FitA- Strength of SupportC- CoverageA+ Formula Quality

L-theanine offers targeted support for calm alertness and acute stress without a stimulant. The clearly stated 150 mg serving falls within a useful range and keeps the formula focused.

Its narrow mechanism is better matched to situational relaxation than comprehensive or sustained mood support. No branded source, purity claim, or independent testing detail is supplied, leaving ingredient quality less certain.

Study evidence
Theanine Supportive 12 studies
Productivity Boost
Productivity Boost
Impact
High effect
B- Goal FitA- Strength of SupportD+ CoverageA+ Formula Quality
Theanine · 150 mg

L-theanine may support calm concentration when stress or overstimulation interferes with work. Used alone, it does not provide the acute alertness or multi-pathway support of a balanced productivity stack.

The amount is well aligned and clearly disclosed in a simple formula. Missing branded sourcing and purity testing are the main quality limitations.

Study evidence
Theanine Supportive 5 studies
Brain Health
Brain Health
Impact
High effect
C Goal FitB+ Strength of SupportD+ CoverageA Formula Quality

L-theanine supports calm, focused alertness without relying on a stimulant. The 150 mg amount is clearly disclosed in a simple vegetable capsule and fits a commonly used range.

The single active provides good depth for attention under stress but does not address memory, brain energy, or neuronal structure. No meaningful product-specific safety concern is evident from the disclosed ingredient and amount.

Study evidence
Theanine Supportive 17 studies

Ingredients

IngredientAmount per serving
L-Theanine
150 mg
Gluten Free Adults 18–50 Vegan Women Vegetarian
Report overview
Theanine · 150 mg OverallScore88
B+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyB+ Value

The clearly identified L-theanine dose is well aligned with relaxation and focus support. The exact amount is disclosed, making the serving easy to assess and use. Quality is less certain because no branded source, purity claim, or independent testing is provided, while the amount delivered offers competitive value.

View ingredientView products
Loading alternative details
87 Performance

L-Theanine 200 mg Double Strength

Swanson
<p>200 mg of clearly identified branded L-theanine gives the formula a clear and relevant foundation. The branded source provides clearer ingredient identity than the original generic theanine listing.</p>
85 Performance

L-Theanine 150 mg

Solgar
<p>150 mg of clearly identified branded L-theanine gives the formula a clear and relevant foundation. The branded source provides clearer ingredient identity than the original generic theanine listing.</p>
87 Performance

L-Theanine 100 mg

California Gold Nutrition
<p>100 mg of clearly identified branded L-theanine gives the formula a clear and relevant foundation. The branded source provides clearer ingredient identity than the original generic theanine listing.</p>
85 Budget

Double Strength L-Theanine 200 mg

NOW
<p>A lower serving cost comes with 200 mg of clearly stated l-theanine. Its disclosed ingredient profile aligns more closely with focused theanine use than the original formula.</p>
84 Budget

L-Theanine 200 mg

Advance Physician Formulas
<p>A lower serving cost comes with 200 mg of clearly stated l-theanine. Its disclosed ingredient profile aligns more closely with focused theanine use than the original formula.</p>
83 Budget

L-Theanine 100 mg

California Gold Nutrition
<p>A lower serving cost comes with 100 mg of clearly stated l-theanine. The ingredient profile remains focused on theanine and offers a practical alternative to the original formula.</p>
85 Value

L-Theanine 200 mg

California Gold Nutrition
<p>200 mg of clearly stated L-theanine is paired with favorable serving-level value in the supplied data. Its disclosed ingredient profile aligns more closely with focused theanine use than the original formula.</p>
85 Value

L-Theanine 100 mg

NOW
<p>100 mg of clearly stated L-theanine is paired with favorable serving-level value in the supplied data. Its disclosed ingredient profile aligns more closely with focused theanine use than the original formula.</p>
84 Value

Suntheanine L-Theanine 125 mg

Natural Factors Stress-Relax
<p>250 mg of clearly identified branded L-theanine is paired with favorable serving-level value in the supplied data. The branded source provides clearer ingredient identity than the original generic theanine listing.</p>
Report alternatives

Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review.
    Williams JL; Everett JM; D'Cunha NM; Sergi D; Georgousopoulou EN; Keegan RJ; McKune AJ; Mellor DD; Anstice N; Naumovski N · Plant foods for human nutrition (Dordrecht, Netherlands) · 2020
    Systematic review9 studies pooledStress Relief Mood Support forTheanine
  2. A Randomized, Triple-Blind, Placebo-Controlled, Crossover Study to Investigate the Efficacy of a Single Dose of AlphaWave® L-Theanine on Stress in a Healthy Adult Population.
    Evans M; McDonald AC; Xiong L; Crowley DC; Guthrie N · Neurology and therapy · 2021
    Randomized trialStress Relief Brain Health forTheanine
  3. L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial.
    Sarris J; Byrne GJ; Cribb L; Oliver G; Murphy J; Macdonald P; Nazareth S; Karamacoska D; Galea S; Short A; Ee C; Birling Y; Menon R; Ng CH · Journal of psychiatric research · 2020
    Randomized trial46 participantsStress Relief Sleep Support forTheanine
  4. Safety and Efficacy of AlphaWave® L-Theanine Supplementation for 28 Days in Healthy Adults with Moderate Stress: A Randomized, Double-Blind, Placebo-Controlled Trial.
    Moulin M; Crowley DC; Xiong L; Guthrie N; Lewis ED · Neurology and therapy · 2024
    Randomized trial30 participantsStress Relief Mental Focus Productivity Boost forTheanine
  5. Promising, but Not Completely Conclusive-The Effect of l-Theanine on Cognitive Performance Based on the Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Clinical Trials.
    Mátyus RO; Szikora Z; Bodó D; Vargáné Szabó B; Csupor É; Csupor D; Tóth B · Journal of clinical medicine · 2025
    Meta-analysis148 participants5 studies pooledMental Focus forTheanine
  6. Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study.
    Baba Y; Inagaki S; Nakagawa S; Kaneko T; Kobayashi M; Takihara T · Journal of medicinal food · 2021
    Randomized trialMental Focus Brain Health Productivity Boost forTheanine
  7. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together.
    Rogers PJ; Smith JE; Heatherley SV; Pleydell-Pearce CW · Psychopharmacology · 2008
    Randomized trial48 participantsMental Focus Productivity Boost forTheanine
  8. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.
    Hidese S; Ogawa S; Ota M; Ishida I; Yasukawa Z; Ozeki M; Kunugi H · Nutrients · 2020
    Randomized trial30 participantsBrain Health Cognitive Support Sleep Support forTheanine
  9. Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
    Payne ER; Aceves-Martins M; Dubost J; Greyling A; de Roos B · Nutrition reviews · 2025
    Meta-analysis50 studies pooledBrain Health Cognitive Support Mental Focus forTheanine
  10. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task.
    Foxe JJ; Morie KP; Laud PJ; Rowson MJ; de Bruin EA; Kelly SP · Neuropharmacology · 2012
    Randomized trial27 participantsBrain Health Cognitive Support forTheanine
  11. Dose-response effect of L-theanine on psychomotor speed, sustained attention, and inhibitory control: a double-blind, placebo-controlled, crossover study.
    Dassanayake TL; Wijesundara D; Kahathuduwa CN; Weerasinghe VS · Nutritional neuroscience · 2023
    Randomized trial32 participantsCognitive Support forTheanine
  12. Acute effects of theanine, caffeine and theanine-caffeine combination on attention.
    Kahathuduwa CN; Dassanayake TL; Amarakoon AMT; Weerasinghe VS · Nutritional neuroscience · 2018
    Clinical trial20 participantsCognitive Support Mental Focus forTheanine
  13. Effect of L-theanine on selective attention in a traffic-related reaction task in sleep-deprived young adults: a double-blind placebo-controlled, crossover study.
    Karunaratne UW; Dassanayake TL · Nutritional neuroscience · 2025
    Randomized trial24 participantsMental Focus forTheanine
  14. l-theanine adjunct to sertraline for major depressive disorder: A randomized, double-blind, placebo-controlled clinical trial.
    Shamabadi A; Kafi F; Arab Bafrani M; Asadigandomani H; A Basti F; Akhondzadeh S · Journal of affective disorders · 2023
    Randomized trial60 participantsMood Support forTheanine
  15. L-theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study.
    Ritsner MS; Miodownik C; Ratner Y; Shleifer T; Mar M; Pintov L; Lerner V · The Journal of clinical psychiatry · 2011
    Randomized trial60 participantsMood Support Stress Relief forTheanine
  16. Comparison of the effects of two amino acids, Gamma-aminobutyric acid (GABA) and L-theanine, on sedation, anxiety, and cognition in preoperative surgical patients - A randomized controlled study.
    Deshpande SS; Kurdi M; Baiju A; Athira AS; Sarasamma AG; Gangadharan AK · Journal of anaesthesiology, clinical pharmacology · 2025
    Randomized trial168 participantsMood Support Stress Relief forTheanine
  17. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary α-amylase activity, trait anxiety and subjective stress.
    Unno K; Tanida N; Ishii N; Yamamoto H; Iguchi K; Hoshino M; Takeda A; Ozawa H; Ohkubo T; Juneja LR; Yamada H · Pharmacology, biochemistry, and behavior · 2014
    Randomized trial20 participantsMood Support forTheanine
  18. Cognitive and affective effects of L-Theanine: a systematic review and meta-analysis of 31 randomized trials.
    Gerolymos C; Saddier E; Boyer L; Fond G · Molecular psychiatry · 2026
    Meta-analysis1,168 participants31 studies pooledProductivity Boost forTheanine
  19. Effects of L-theanine on cognition, mood and sleep: evidence from human trials.
    Cotter J; Kilpatrick HE · Frontiers in nutrition · 2026
    Narrative reviewProductivity Boost forTheanine
  20. Comparison Between Efficacy of Oral Melatonin and Oral L-theanine in Improving Sleep in Cancer Patients Suffering From Insomnia: A Randomised Double-blinded Placebo-controlled Study.
    Kurdi MS; As A; Ladhad DA; Mitragotri MV; Baiju A · Indian journal of palliative care · 2024
    Randomized trial120 participantsSleep Support forTheanine
  21. The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis.
    Bulman A; D'Cunha NM; Marx W; Turner M; McKune A; Naumovski N · Sleep medicine reviews · 2025
    Meta-analysis897 participants19 studies pooledSleep Support forTheanine
  22. In Search of a Safe Natural Sleep Aid.
    Rao TP; Ozeki M; Juneja LR · Journal of the American College of Nutrition · 2016
    Narrative reviewSleep Support forTheanine
  23. Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial.
    White DJ; de Klerk S; Woods W; Gondalia S; Noonan C; Scholey AB · Nutrients · 2016
    Randomized trial34 participantsStress Relief forTheanine