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L-Theanine 200 mg

DaVinci Laboratories
4.7
★ ★ ★ ★ ★
(73 ratings)
Theanine 200 mg
Product Image
Score82
Branded Suntheanine at a practical one-capsule dose offers strong quality and convenience, with price as the main trade-off.
How scoring works
Quantity:120 Capsule(s) • (120 servings)
Goals:
Stress Relief
Brain Health
Mental Focus
Sleep Support
Cognitive Support
Mood Support
Productivity Boost

Score 82

Branded Suntheanine at a practical one-capsule dose offers strong quality and convenience, with price as the main trade-off.
How scoring works
$49.99($0.41 per serving)
Vitacost
$ 49.99
iHerb
$ 80.20
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Analysis

Suntheanine is explicitly identified as the L-theanine source at 200 mg per capsule. The dose is practical for either daytime calm or an evening wind-down routine.

A single-active formula makes the effect and amount easy to judge. No supporting ingredients are needed for users specifically seeking theanine, though inactive-ingredient information is not included in the supplied details.

Quality and convenience are the main attractions, while economy is less compelling. It fits users willing to pay more for a branded source and one-capsule serving.

Who is it for
  • Adults seeking calm focus or relaxation
  • Users who prefer a branded L-theanine source
Best for
  • One-capsule theanine dosing
  • A focused daytime or evening routine

Pros

  • Uses branded Suntheanine L-theanine
  • Provides a practical 200 mg amount
  • Needs only one capsule per serving

Cons

  • Costs more per serving than many alternatives
  • Supplied details omit inactive ingredients
  • Offers no lower-dose option within one capsule

Warnings

  • A 200 mg L-theanine capsule may cause drowsiness in sensitive users.
  • Alcohol, sedatives, and sleep aids may intensify the calming effect.
  • L-theanine may add to the effects of antihypertensive medicine in people prone to low blood pressure.

Nutrient quality

97 Highest impact

The branded source and clearly stated amount support reliable theanine use. The focused formula avoids dilution from unrelated actives.

.

Ingredient transparency

86 Highest impact

Active amounts are clear without a hidden blend. Complete directions and inactive ingredients remain unavailable.

.

Customer satisfaction

62 Moderate impact

The supplied average is strong and supported by moderate volume. No review themes were provided, so consistency and purpose-specific experience cannot be assessed.

.

Value for money

77 High impact

An effective dose provides good core value. The focused formula avoids paying for unrelated additions.

.
Report analysis

Goals

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

Branded L-theanine is closely matched to calm, focused stress support without relying on a broad wellness claim. Human evidence for L-theanine supports relaxed attention, although it does not address every part of the stress response.

The clearly disclosed serving uses a well-characterized amount and a high-purity branded source. A focused one-ingredient design provides excellent depth with little unnecessary padding.

Study evidence
Theanine Supportive 16 studies
Brain Health
Brain Health
Impact
Highest effect
B+ Goal FitA Strength of SupportC CoverageA Formula Quality

Suntheanine provides a focused and well-characterized option for calm attention. Its narrow scope does not address memory, brain structure, or broader neuroprotection.

The active isomer, branded source, and 200 mg amount are all clearly disclosed. The streamlined single-ingredient design makes its likely effect easier to judge and avoids unnecessary safety complexity.

Study evidence
Theanine Supportive 17 studies
Mental Focus
Mental Focus
Impact
Highest effect
B+ Goal FitA+ Strength of SupportD+ CoverageA+ Formula Quality
Theanine · 200 mg

Suntheanine provides a well-characterized L-theanine source at a useful amount for calm, steady attention. Its evidence is strongest for reducing tension and smoothing focus, particularly when caffeine is obtained separately.

The single-ingredient design offers excellent dose clarity and avoids irrelevant actives. Users seeking stronger alertness may find the narrow calming pathway insufficient on its own.

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

Suntheanine provides a well-characterized L-theanine source at a strong 200 mg amount. It may support mental calm when racing thoughts interfere with sleep.

The single-ingredient design is transparent and avoids unnecessary additions, but it does not directly regulate circadian timing or cover physical relaxation. Sleep-specific evidence is also less robust than evidence for melatonin.

Study evidence
Theanine Supportive 8 studies
Cognitive Support
Cognitive Support
Impact
Highest effect
B- Goal FitA Strength of SupportD+ CoverageA+ Formula Quality
Theanine · 200 mg

Branded Suntheanine provides a well-characterized L-theanine form at a strong calm-focus amount. The simple capsule is well suited to users seeking reduced tension without a stimulant.

The effect is narrow and generally subtler than a broader cognitive stack. No memory, cerebral-circulation, or neuroplasticity active is included.

Study evidence
Theanine Supportive 25 studies
Mood Support
Mood Support
Impact
High effect
C+ Goal FitA Strength of SupportD+ CoverageA Formula Quality

Suntheanine may promote a calmer emotional state and reduce stress-related tension without strong sedation. The product is useful for situational calm but does not address broader mood pathways such as serotonin production or adaptation.

The branded L-theanine source and substantial amount provide excellent dose and purity confidence. A single-active design offers strong depth and avoids unrelated additions.

Study evidence
Theanine Supportive 12 studies
Productivity Boost
Productivity Boost
Impact
High effect
C Goal FitA- Strength of SupportC CoverageB Formula Quality
Theanine · 200 mg

Theanine provides a useful but incomplete connection to productivity. The principal relevant amounts appear substantial enough to contribute in practice.

Coverage is concentrated on calm focus and stress resilience. The focused design leaves other major alertness, cognition, or stress pathways uncovered.

Study evidence
Theanine Supportive 5 studies

Ingredients

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

Explicit L-theanine identity and Suntheanine branding provide strong isomer and purity confidence. The clearly disclosed amount falls within the optimal range for calm and focused support. Suntheanine quality and competitive dose-adjusted cost make this a well-balanced standalone option.

View ingredientView products
Loading alternative details
87 Performance

L-Theanine 200 mg Double Strength

Swanson
<p>Branded Suntheanine provides a substantial, focused amount without unrelated active ingredients, matching the original's focused role with stronger ingredient identity or dose flexibility. It does not include melatonin or other bedtime ingredients, so its role is broader than sleep alone.</p>
85 Performance

L-Theanine 150 mg

Solgar
<p>Branded Suntheanine provides a moderate amount that supports calm focus without pushing the dose high, matching the original's focused role with stronger ingredient identity or dose flexibility. The smaller amount may feel less pronounced for users who prefer a stronger single serving.</p>
83 Performance

L-Theanine 200 mg

Country Life
<p>Branded Suntheanine supplies a substantial amount, while vitamin B6 is fully disclosed as a secondary ingredient, matching the original's focused role with stronger ingredient identity or dose flexibility. Vitamin B6 is not necessary for theanine support, and the serving cost exceeds basic generic options.</p>
85 Budget

L-Theanine 200 mg

California Gold Nutrition
<p>A substantial L-theanine amount provides focused calming support at a lower serving cost than the original. No branded source or purity marker is supplied.</p>
85 Budget

Double Strength L-Theanine 200 mg

NOW
<p>A substantial L-theanine amount provides focused support with a modest inositol addition at a lower serving cost than the original. Generic sourcing provides less ingredient assurance, and the inositol amount adds little.</p>
84 Budget

L-Theanine 200 mg

Advance Physician Formulas
<p>A substantial L-theanine amount provides simple calm-focus support at a lower serving cost than the original. No branded source or purity marker is supplied.</p>
87 Value

L-Theanine 100 mg

California Gold Nutrition
<p>Branded AlphaWave L-theanine provides a clearly identified amount for moderate calm-focus support, preserving the original's calm-focus role at a lower serving cost. The amount is lower than the common single-serving amount used by many other options.</p>
82 Value

Theanine 100 mg

Jarrow Formulas
<p>A moderate L-theanine amount provides a simple option for lighter calm-focus support, preserving the original's calm-focus role at a lower serving cost. No branded source or purity marker is supplied.</p>
85 Value

L-Theanine 100 mg

NOW
<p>A practical L-theanine amount pairs with decaffeinated green tea, preserving the original's calm-focus role at a lower serving cost. The green-tea catechins are not standardized, and the theanine source is not branded.</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. 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