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L-Theanine 150 mg

Solgar
4.7
★ ★ ★ ★ ★
(768 ratings)
Theanine 150 mg
Product Image
Score85
A well-balanced branded-theanine capsule with strong quality and value for calm focus and stress.
How scoring works
Quantity:60 Capsule(s) • (60 servings)
Goals:
Stress Relief
Mental Focus
Brain Health
Cognitive Support
Sleep Support
Mood Support
Productivity Boost

Score 85

A well-balanced branded-theanine capsule with strong quality and value for calm focus and stress.
How scoring works
$24.64($0.41 per serving)
Pure Formulas
$ 26.99
iHerb
$ 25.49
Amazon
$ 24.64
Vitacost
$ 26.95
Daily Vita
$ 26.99
Report prices

Analysis

The capsule uses branded Suntheanine at a balanced amount between a starting and high serving. It fits daytime calm, focused work, and pre-sleep relaxation.

The formula contains no competing actives, which keeps response easy to judge. It does not directly address memory, alertness, or sleep maintenance.

Source identity and competitive cost make it a strong general theanine choice. The middle-range amount should suit a wide range of users.

Who is it for
  • Adults wanting branded L-theanine
  • Users seeking balanced daytime calm
  • People preferring a single active
Best for
  • Calm focus
  • Situational stress
  • Pre-sleep relaxation

Pros

  • Branded Suntheanine
  • Balanced preferred-range amount
  • Simple formula
  • Competitive practical value

Cons

  • Single calming pathway
  • No alertness support
  • No memory-specific ingredients
  • May be too relaxing for very sensitive users

Warnings

  • Theanine may cause drowsiness in sensitive users
  • Sedatives and alcohol may intensify relaxation
  • Blood-pressure medicines may increase the risk of lightheadedness

Nutrient quality

97 Highest impact

Suntheanine provides strong purity and ingredient-identity assurance. The active amount sits in a useful range for calm focus.

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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.

.

Customer satisfaction

68 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.

.

Value for money

89 Highest impact

Branded ingredient quality and a useful amount justify the price well. The serving provides good value for standardized theanine.

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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

Suntheanine provides targeted support for calm attention without relying on sedation. The fully disclosed 150 mg amount sits within a useful range and the branded source improves quality confidence.

The formula addresses one neurotransmitter-related pathway rather than broader stress adaptation or mineral support. Its focused design is a good fit for acute mental tension when alertness still matters.

Study evidence
Theanine Supportive 16 studies
Mental Focus
Mental Focus
Impact
Highest effect
A Goal FitA Strength of SupportC+ CoverageA+ Formula Quality
Theanine · 150 mg

Suntheanine provides a clinically studied form of L-theanine that may support calm, steady attention. The serving amount sits within a commonly used range for relaxation without marked drowsiness.

The single-active formula is fully disclosed and highly focused. It may be especially useful alongside a separately managed caffeine source, though it does not provide stimulation on its own.

Study evidence
Theanine Supportive 19 studies
Brain Health
Brain Health
Impact
Highest effect
A- Goal FitA+ Strength of SupportC- CoverageA+ Formula Quality

Suntheanine supports calm attention and mental performance without relying on strong stimulation. The 150 mg amount sits within a useful range and the branded source adds strong quality assurance.

Its single pathway is narrow but well executed for people whose focus is disrupted by tension. The streamlined formula avoids unrelated nutrients and overlapping nootropics.

Study evidence
Theanine Supportive 17 studies
Cognitive Support
Cognitive Support
Impact
Highest effect
A- Goal FitA+ Strength of SupportD+ CoverageA Formula Quality
Theanine · 150 mg

L-theanine is directly suited to calm focus and may reduce distracting tension without acting as a sedative. The branded source has strong quality support and is clearly identified.

The 150 mg serving sits in a practical effective range. The formula is intentionally narrow, so it does not add memory, circulation, or structural brain support.

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 users whose racing thoughts delay sleep. The 150 mg amount is useful and uses a well-characterized branded source.

It is transparent and focused. It does not regulate circadian rhythm or provide mineral support, so its value is strongest for tension-related sleep onset.

Study evidence
Theanine Supportive 8 studies
Mood Support
Mood Support
Impact
Highest effect
B Goal FitA+ Strength of SupportD+ CoverageA+ Formula Quality

Suntheanine at 150 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
Productivity Boost
Productivity Boost
Impact
Highest effect
B- Goal FitA Strength of SupportC CoverageA+ Formula Quality
Theanine · 150 mg

The branded 150 mg L-theanine amount may promote calm attention and reduce stress-related distraction without acting as a strong sedative. Suntheanine sourcing and precise dose disclosure provide strong ingredient confidence.

Used alone, L-theanine offers less acute alertness than a caffeine-theanine stack and covers only one productivity pathway. The evidence is most consistent for relaxation and attention quality rather than a large increase in work output.

Study evidence
Theanine Supportive 5 studies

Ingredients

IngredientAmount per serving
Suntheanine L-Theanine
150 mg
Gluten Free Adults 18–50 Vegan Kosher Dairy Free Sugar Free Vegetarian
Report overview
Theanine · 150 mg OverallScore96
A+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyB+ Value

The 150 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 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
  2. 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
  3. Current Evidence on Common Dietary Supplements for Sleep Quality.
    Esquivel MK; Ghosn B · American journal of lifestyle medicine · 2025
    Narrative reviewSleep Support forTheanine
  4. 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
  5. 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 participantsSleep Support Brain Health Cognitive Support forTheanine
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  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 participantsMental Focus Cognitive Support forTheanine
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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