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L-Theanine 200 mg Double Strength

Swanson
4.8
★ ★ ★ ★ ★
(1136 ratings)
Theanine 200 mg
Product Image
Score87
A high-quality, substantial Suntheanine capsule with excellent focused use and value, but narrow pathway coverage.
How scoring works
Quantity:60 Veggie Cap(s) • (60 servings)
Goals:
Stress Relief
Mental Focus
Sleep Support
Brain Health
Productivity Boost
Mood Support
Cognitive Support

Score 87

A high-quality, substantial Suntheanine capsule with excellent focused use and value, but narrow pathway coverage.
How scoring works
$22.59($0.37 per serving)
iHerb
$ 25.49
Amazon
$ 22.59
iHerb
$ 25.49
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Analysis

The capsule provides a substantial amount of branded Suntheanine. It is well matched to calm focus, stress-related tension, and evening relaxation.

The single-ingredient design makes individual response easy to track. It does not add alertness, memory, or sleep-maintenance ingredients.

Strong source assurance and sensible cost create a compelling focused option. Sensitive daytime users may prefer a lower amount.

Who is it for
  • Adults seeking strong calm-focus support
  • Users who value branded theanine
  • People wanting one simple capsule
Best for
  • Stress relief
  • Calm concentration
  • Pre-sleep relaxation

Pros

  • Branded Suntheanine
  • Substantial preferred-range amount
  • Single active ingredient
  • Competitive value

Cons

  • Narrow single pathway
  • No memory support
  • No direct alertness ingredient
  • May feel too relaxing for some daytime users

Warnings

  • The serving may cause drowsiness in sensitive users
  • Sedatives or alcohol may compound sleepiness
  • Antihypertensive users should watch for dizziness or lightheadedness

Nutrient quality

98 Highest impact

Suntheanine provides strong purity and ingredient-identity assurance. The active amount is substantial and well aligned with focused use.

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Ingredient transparency

84 Highest impact

Every listed active has a specific amount, which makes the core formula straightforward to assess. The supplied data omits a complete excipient list and full intake directions.

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Customer satisfaction

70 High impact

The supplied aggregate satisfaction signal is favorable. A large amount of feedback makes that aggregate signal reasonably stable, but no narrative evidence was provided.

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Value for money

92 Highest impact

A substantial branded dose strongly supports the asking level. Serving-level value is strong for standardized theanine.

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Report analysis

Goals

Stress Relief
Impact
Highest effect
A Goal FitA+ Strength of SupportC+ CoverageA+ Formula Quality
Theanine · 200 mg

A 200 mg serving of branded L-theanine is well targeted for calm focus without relying on a sedative herb or stimulant. Suntheanine provides strong source standardization and clear identity.

The formula is highly focused on neurotransmitter-related relaxation and does not cover adaptogenic or foundational mineral pathways. Evidence supports acute stress moderation and relaxed attention, though responses can vary between individuals.

Study evidence
Theanine Supportive 16 studies
Mental Focus
Impact
Highest effect
A Goal FitA+ Strength of SupportC+ CoverageA+ Formula Quality
Theanine · 200 mg

Suntheanine provides a clinically studied form of L-theanine at a strong calm-focus amount. It may ease tension and support steadier attention without acting as a stimulant.

The one-capsule formula is fully disclosed and tightly targeted. Pairing it with a separately controlled caffeine source may broaden its effect, while using it alone favors calmness over increased alertness.

Study evidence
Theanine Supportive 19 studies
Sleep Support
Impact
Highest effect
B+ Goal FitA+ Strength of SupportC+ CoverageA+ Formula Quality
Theanine · 200 mg

The 200 mg Suntheanine amount supports relaxation and may ease the transition into sleep when mental arousal is the main barrier. It does not directly regulate circadian timing or act as a strong sedative.

The branded L-theanine source and exact amount provide unusually strong form and purity disclosure.

Study evidence
Theanine Supportive 8 studies
Brain Health
Impact
Highest effect
B+ Goal FitA+ Strength of SupportC CoverageA+ Formula Quality

L-theanine is directly relevant to calm focus and may support attention without sedation. The disclosed amount is well aligned with common cognitive use.

The clinically studied Suntheanine source and individual amount are clearly disclosed. The formula mainly targets calm attention through alpha-wave and inhibitory signaling.

Study evidence
Theanine Supportive 17 studies
Productivity Boost
Impact
Highest effect
B Goal FitA+ Strength of SupportC- CoverageA+ Formula Quality
Theanine · 200 mg

Suntheanine at 200 mg provides well-supported calm-focus dosing with strong source transparency. It may reduce stress-related distraction without acting as a stimulant.

The product is narrow but deep, and human performance evidence is clearest when L-theanine is paired with caffeine. Used alone, it suits calm attention better than an acute energy boost.

Study evidence
Theanine Supportive 5 studies
Mood Support
Impact
Highest effect
B Goal FitA+ Strength of SupportD+ CoverageA+ Formula Quality

Suntheanine at 200 mg offers targeted support for calmness and stress-related tension without acting as a heavy sedative. Human evidence is useful for relaxation, though effects on persistent low mood are less established.

The branded theanine form provides strong quality assurance in a clean single-ingredient formula. The product is best viewed as focused calming support rather than a broad mood-stabilizing strategy.

Study evidence
Theanine Supportive 12 studies
Cognitive Support
Impact
High effect
B- Goal FitA+ Strength of SupportD CoverageA+ Formula Quality
Theanine · 200 mg

L-theanine may support calm attention and reduce stress-related distraction without acting as a sedative for most people. The 200 mg amount is clearly disclosed through a well-characterized branded source.

Evidence is more consistent for relaxation and attention under stress than for memory improvement, and the effect may be stronger when paired with caffeine. The narrow formula does not address circulation, acetylcholine, or long-term neuroprotection.

Study evidence
Theanine Supportive 25 studies

Ingredients

IngredientAmount per serving
Suntheanine L-Theanine
200 mg
Adults 18–50
Report overview
Theanine · 200 mg OverallScore96
A+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyB+ Value

The 200 mg serving falls in the preferred range for calm focus. The clinically studied Suntheanine source adds strong purity assurance. The normalized cost falls in the competitive range.

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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. 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