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Theanine 300 mg
Product Image
Score61
A substantial 300 mg theanine amount is overshadowed by a much larger undisclosed extract blend. Hidden ingredients, three capsules, and poor value create major uncertainty.
How scoring works
Quantity:60 Capsule(s) • (20 servings)
Goals:
Sleep Support
Stress Relief

Score 61

A substantial 300 mg theanine amount is overshadowed by a much larger undisclosed extract blend. Hidden ingredients, three capsules, and poor value create major uncertainty.
How scoring works
$27.55($1.37 per serving)
Pure Formulas
$ 27.55
Amazon
$ 29.00
Vitacost
$ 29.00
iHerb
$ 29.00
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Analysis

A substantial 300 mg L-theanine amount may support calm attention and relaxation. Most of the formula, however, sits inside a 1,050 mg proprietary extract blend whose ingredients and amounts are not disclosed.

The known theanine portion may suit people seeking stronger calming support. The hidden blend prevents reliable assessment of cognitive value, sedation, interactions, or formulation coherence.

Three capsules are needed per serving, and the serving cost is high. Generic theanine sourcing and extensive blend opacity make this much harder to evaluate than transparent alternatives.

Who is it for
  • Adults specifically comfortable with the proprietary blend
  • People seeking a higher theanine amount
  • Users able to review the complete current label
Best for
  • Higher-dose relaxation
  • Users already familiar with the full blend
  • Occasional use when sedation is acceptable

Pros

  • Substantial 300 mg L-theanine amount
  • Theanine is disclosed separately
  • Potential for strong calming support

Cons

  • Most ingredients are hidden in a proprietary blend
  • Three capsules per serving
  • High serving cost
  • Interactions and tolerability are difficult to assess

Warnings

  • The 300 mg L-theanine amount may cause drowsiness in sensitive users, so first use should not coincide with driving or other attention-critical tasks.
  • The unidentified 1,050 mg extract blend prevents ingredient-specific interaction screening; verify the full current label before use.

Nutrient quality

71 High impact

L-theanine is a defined amino acid, although no branded source or purity marker is supplied. The L-theanine amount is high and may suit users seeking a more pronounced calming serving.

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Ingredient transparency

57 Moderate impact

Named actives have amounts, but the proprietary blend is only partly disclosed. A proprietary blend hides the amounts of its individual components.

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Customer satisfaction

60 Moderate impact

The supplied aggregate rating is strong, although no specific comments are included. The moderate rating count provides a useful aggregate signal.

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Value for money

55 Moderate impact

Formula quality provides strong support for the product positioning. Dose-adjusted serving value appears weak, while opaque or lightly dosed additions reduce efficiency.

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Report analysis

Goals

Sleep Support
Impact
High effect
B+ Goal FitB Strength of SupportC- CoverageD+ Formula Quality
Theanine · 300 mg

The disclosed theanine amount may support relaxation before bed. It provides 300 mg of L-theanine alongside a large proprietary extract formula for a defined sleep-related pathway.

The generic source lacks a purity standard and the proprietary blend hides the identity and amounts of other actives. The large undisclosed extract blend makes ingredient-specific interactions and tolerability difficult to assess.

Study evidence
Theanine Supportive 8 studies
Stress Relief
Impact
High effect
B Goal FitB Strength of SupportC- CoverageD+ Formula Quality
Theanine · 300 mg

A 300 mg L-theanine serving provides strong non-sedating calming support. The large proprietary extract blend may add complementary botanicals, but its hidden contents and doses cannot be verified.

Theanine itself is well dosed and clearly identified, while most of the formula remains opaque. Unknown blend ingredients prevent a reliable check for stimulants, sedatives, interactions, or unnecessary repetition.

Study evidence
Theanine Supportive 16 studies
Productivity Boost
Impact
Moderate effect
C+ Goal FitB- Strength of SupportC CoverageD- Formula Quality
Theanine · 300 mg

A substantial L-theanine amount may support calm attention and reduce stress-related distraction. The much larger proprietary extract formula cannot be assessed for focus, energy, or safety.

The theanine amount is clear and useful, but the hidden blend dominates the formula. Missing ingredient identities and doses prevent a dependable productivity assessment.

Study evidence
Theanine Supportive 5 studies
Cognitive Support
Impact
Moderate effect
B- Goal FitB- Strength of SupportD+ CoverageF Formula Quality
Theanine · 300 mg

L-theanine supplies a meaningful calming-focus mechanism that may support attention under stress. The remainder of the formula cannot be evaluated because its herbal extracts are hidden in a proprietary blend.

The 300 mg theanine amount provides strong depth for relaxed attention. Hidden ingredient identities and doses prevent judging whether the large blend adds useful synergy, sedation, or unnecessary padding.

Study evidence
Theanine Supportive 25 studies
Brain Health
Impact
Moderate effect
B- Goal FitC Strength of SupportC- CoverageD Formula Quality

L-theanine at 300 mg provides substantial support for calm attention. The large proprietary extract formula prevents evaluation of the remaining cognitive claims.

The disclosed theanine has useful depth, but the hidden ingredients make pathway breadth and interaction logic uncertain. A formula dominated by an opaque blend offers much less confidence than the clearly listed active suggests.

Study evidence
Theanine Supportive 17 studies
Mental Focus
Impact
Moderate effect
C+ Goal FitC- Strength of SupportD- CoverageF Formula Quality
Theanine · 300 mg

A substantial 300 mg L-theanine amount may support calm focus, but it may also feel sedating for some users. The much larger proprietary extract formula prevents a clear understanding of the product's other cognitive or calming effects.

Theanine is disclosed separately, while the remaining blend is opaque. Unknown ingredients and amounts create avoidable safety and interaction uncertainty even though the named active itself is straightforward.

Study evidence
Theanine Supportive 19 studies
Mood Support
Impact
Moderate effect
C+ Goal FitC- Strength of SupportD- CoverageF Formula Quality

A substantial L-theanine amount may support calmness and lower stress-related tension. The much larger proprietary extract formula hides most ingredients, so the product's broader mood effects and interaction risks cannot be judged.

Theanine is disclosed separately, while the majority of the formula is opaque. Unknown ingredients and amounts create avoidable safety uncertainty despite the straightforward named active.

Study evidence
Theanine Supportive 12 studies

Ingredients

IngredientAmount per serving
L-Theanine
300 mg
Proprietary Extract Formula
1050 mg
Gluten Free Adults 18–50
Report overview
Theanine · 300 mg OverallScore74
B+ Active Ingredient Quality & BioavailabilityB Dose, Safety & Label TransparencyD+ Value

The clearly identified L-theanine provides a substantial amount that may support relaxation, though the higher serving may feel sedating for some people. The generic source lacks a branded form or stated purity standard, leaving its quality less certain. The dose is disclosed separately, but the cost efficiency is only moderate for the amount supplied.

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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. 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
  4. 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
  5. Effect of Combined Ingestion of L-Theanine and L-Arginine for Short-Term Psychological Stress in Young Adults: A Randomized Placebo-Controlled Study.
    Furushima D; Sugiyama I; Nomura Y; Unno K; Yamada H · Journal of nutritional science and vitaminology · 2023
    Randomized trial120 participantsStress Relief forTheanine
  6. 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
  7. Acute effects of theanine, caffeine and theanine-caffeine combination on attention.
    Kahathuduwa CN; Dassanayake TL; Amarakoon AMT; Weerasinghe VS · Nutritional neuroscience · 2018
    Clinical trial20 participantsMental Focus Cognitive Support forTheanine
  8. L-theanine improves neurophysiological measures of attention in a dose-dependent manner: a double-blind, placebo-controlled, crossover study.
    Dassanayake TL; Kahathuduwa CN; Weerasinghe VS · Nutritional neuroscience · 2022
    Randomized trial27 participantsMental Focus forTheanine
  9. 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 participantsMental Focus Cognitive Support forTheanine
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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 trialBrain Health Mental Focus Productivity Boost forTheanine
  15. 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 participantsMental Focus Productivity Boost Stress Relief forTheanine
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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