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Smart Caffeine with L-Theanine

NS Natural Stacks
4.4
★ ★ ★ ★ ★
(819 ratings)
Theanine 200 mg
Caffeine 100 mg
Product Image
Score84
A simple green-coffee caffeine and theanine pairing provides strong value for daytime focus. Sensitive users may still experience stimulant-related sleep or anxiety effects.
How scoring works
Quantity:60 Capsule(s) • (60 servings)
Goals:
Productivity Boost
Energy
Mental Focus
Brain Health
Cognitive Support
Metabolism Boost
Fitness
Weight Loss

Score 84

A simple green-coffee caffeine and theanine pairing provides strong value for daytime focus. Sensitive users may still experience stimulant-related sleep or anxiety effects.
How scoring works
$18.95($0.31 per serving)
iHerb
$ 19.95
Pure Formulas
$ 19.95
Amazon
$ 18.95
Report prices

Analysis

Green-coffee caffeine at 100 mg provides moderate alertness, while 200 mg L-theanine supports calmer focus. The clear two-to-one ratio is well suited to daytime cognitive use.

The formula directly supports attention and productivity but does not address memory, neural structure, or broad metabolic health. Caffeine makes it a poor fit for sleep and potentially inconsistent for stress-sensitive users.

One capsule, 60 servings, and low cost support excellent practical value. Theanine purity, caffeine standardization, and independent testing are not disclosed.

Who is it for
  • Adults seeking calm alertness
  • People who prefer green-coffee caffeine
  • Value-focused productivity users
Best for
  • Mental focus
  • Productivity
  • Daytime energy

Pros

  • Provides 200 mg L-theanine
  • Includes 100 mg green-coffee caffeine
  • Simple one-capsule formula
  • Favorable serving value

Cons

  • Generic theanine source
  • No controlled-release caffeine
  • Testing details are absent
  • Narrow acute-focus coverage

Warnings

  • Caffeine may cause jitteriness, palpitations, anxiety, or sleep disruption
  • Avoid late-day use
  • Account for other caffeine sources

Nutrient quality

91 Highest impact

L-theanine and green-coffee-sourced caffeine are clearly identified, though no controlled-release feature is present. Both theanine and caffeine are present at meaningful, balanced amounts.

.

Ingredient transparency

82 Highest impact

Active amounts are stated and no proprietary blend hides a core dose. Missing excipient details and complete use directions leave the supplied label information incomplete.

.

Customer satisfaction

62 Moderate impact

The supplied aggregate satisfaction average provides a broad signal, while the response volume determines how stable it appears. No comment-level evidence is available to assess repeated complaints or confirm intended-use experiences.

.

Value for money

96 Highest impact

Useful active delivery supports favorable serving value. The two-active formula shows no low-value padding.

.
Report analysis

Goals

Productivity Boost
Productivity Boost
Impact
Highest effect
A+ Goal FitA+ Strength of SupportA- CoverageA+ Formula Quality
Theanine · 200 mgCaffeine · 100 mg

Caffeine and L-theanine directly support alert, steady attention through complementary effects. Both ingredients are supplied at useful, clearly stated amounts.

The focused two-ingredient design gives strong short-term support rather than broad cognitive coverage. The caffeine may cause jitters or disturb sleep in sensitive users, particularly when taken later in the day.

Study evidence
Caffeine Supportive 108 studies
Theanine Supportive 5 studies
Energy
Energy
Impact
Highest effect
A+ Goal FitA+ Strength of SupportB+ CoverageA+ Formula Quality
Caffeine · 100 mg

Caffeine provides a reliable acute lift in alertness, while L-theanine may promote calmer focus. Both amounts are well aligned with the intended cognitive effect.

The concise formula avoids competing stimulants and proprietary blends. Caffeine may disrupt sleep or worsen jitteriness and anxiety in sensitive users, especially when taken late in the day.

Study evidence
Caffeine Supportive 68 studies
Theanine Not classified

No linked studies yet.

Mental Focus
Mental Focus
Impact
Highest effect
A+ Goal FitA+ Strength of SupportB- CoverageA+ Formula Quality
Theanine · 200 mgCaffeine · 100 mg

Caffeine and L-theanine form a well-supported calm-alertness pairing for acute focus. Caffeine improves vigilance while the higher theanine amount may soften tension or jitteriness.

Both actives are fully disclosed at purposeful amounts, and the green-coffee caffeine source is identified. The 100 mg caffeine amount can still disrupt sleep or cause palpitations in caffeine-sensitive users, especially when combined with other stimulants.

Study evidence
Caffeine Supportive 128 studies
Theanine Supportive 19 studies
Brain Health
Brain Health
Impact
Highest effect
A Goal FitA Strength of SupportB- CoverageA+ Formula Quality

Caffeine and L-theanine form a well-supported pairing for alertness with smoother focus. The two-to-one theanine-to-caffeine balance is practical for acute cognitive performance.

Exact amounts and the green-coffee caffeine source are clearly disclosed, though the theanine source is generic. The 100 mg caffeine amount may cause jitters, faster heartbeat, or sleep disruption in caffeine-sensitive users.

Study evidence
Theanine Supportive 17 studies
Cognitive Support
Cognitive Support
Impact
Highest effect
A Goal FitA Strength of SupportB- CoverageA+ Formula Quality
Theanine · 200 mg

Caffeine and L-theanine form a well-supported pairing for alertness with smoother focus. The two-to-one theanine-to-caffeine balance is practical for acute cognitive performance.

Exact amounts and the green-coffee caffeine source are clearly disclosed, though the theanine source is generic. The 100 mg caffeine amount may cause jitters, faster heartbeat, or sleep disruption in caffeine-sensitive users.

Study evidence
Theanine Supportive 25 studies
Metabolism Boost
Metabolism Boost
Impact
Highest effect
A Goal FitA Strength of SupportC CoverageA+ Formula Quality
Caffeine · 100 mg

Caffeine directly increases short-term thermogenesis and energy expenditure. The 100 mg amount is clearly disclosed and paired with 200 mg of L-theanine for a calmer stimulant profile.

The combination is streamlined but covers only the stimulant pathway. Caffeine may cause jitters, a faster heartbeat, or sleep disruption in sensitive users, especially when taken late.

Study evidence
Caffeine Disputed 40 studies

Ingredients

IngredientAmount per serving
L-Theanine
200 mg
Caffeine (Green Coffee)
 100 mg
Gluten Free Adults 18–50 Women Children 4+
Report overview
Theanine · 200 mg OverallScore92
B+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyA+ Value
+1

The fully disclosed L-theanine dose is well aligned with calm focus support and pairs with caffeine for alertness. Its generic source offers no added purity assurance, while the active amount is exceptionally cost-efficient. The 100 mg caffeine dose may cause jitters, sleep disruption, or a faster heartbeat in caffeine-sensitive users.

View ingredientView products
Caffeine (Green Coffee) · 100 mg OverallScore76
D- Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyA+ Value

The clearly disclosed caffeine dose falls within the preferred range for focus and performance. Green coffee identifies the botanical source, but no caffeine standardization or controlled-release technology is stated. L-theanine adds a non-stimulant companion ingredient, and the serving cost offers favorable value.

View ingredientView products
Loading alternative details
84 Performance

L-Theanine & Caffeine

SR Sports Research
<p>Two hundred milligrams of theanine with 100 mg PurCaf green-coffee caffeine provides a clear two-to-one calm-focus balance, giving a clearer or more purpose-specific option than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. The softgel oil is not necessary for these water-soluble ingredients, and caffeine timing still matters.</p>
87 Performance

L-Theanine 200 mg Double Strength

Swanson
<p>A focused 200 mg Suntheanine serving offers substantial branded theanine for calm attention and relaxation, giving a clearer or more purpose-specific option than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. It omits caffeine, so users seeking strong immediate energy would need a different approach.</p>
87 Performance

L-Theanine 100 mg

California Gold Nutrition
<p>A clearly disclosed 100 mg AlphaWave L-theanine serving provides branded, focused support for calm attention, giving a clearer or more purpose-specific option than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. The caffeine-free design favors relaxation and sensitivity but will not reproduce stimulant-driven energy.</p>
87 Budget

Caffeine 200 mg

ALLMAX
<p>A clearly disclosed 200 mg anhydrous caffeine dose provides direct short-term energy and focus at a lower serving cost than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. It has no theanine to temper stimulation, so sensitive users may experience jitters or sleep disruption.</p>
85 Budget

L-Theanine 200 mg

California Gold Nutrition
<p>A focused 200 mg L-theanine serving supports calm attention without adding stimulant exposure at a lower serving cost than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. No branded source or purity marker is supplied, and it will not provide the energy effect of caffeine.</p>
81 Budget

Natural Caffeine

BodyTech
<p>A clearly disclosed 200 mg coffee-derived caffeine dose provides simple stimulant support with a named source at a lower serving cost than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. The formula lacks theanine and may cause jitters or sleep disruption in sensitive users.</p>
85 Value

Double Strength L-Theanine 200 mg

NOW
<p>A 200 mg L-theanine amount with 100 mg inositol provides simple calm-focus support at an equal or lower serving cost compared with the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. Generic theanine offers less purity assurance than a branded form, and the inositol amount adds little.</p>
82 Value

Caffeine 200 mg

Best Naturals
<p>A clearly disclosed 200 mg anhydrous caffeine serving provides inexpensive, predictable stimulation at an equal or lower serving cost compared with the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. It lacks theanine and offers little beyond stimulation, with routine jitter and sleep-disruption concerns.</p>
83 Value

TheanineUP Focused Energy

California Gold Nutrition
<p>An even 100 mg theanine and 100 mg coffee-fruit caffeine pairing supports alert focus, with cocoa and matcha adding mild complementary stimulation at an equal or lower serving cost compared with the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. The one-to-one ratio may feel less calming than a two-to-one formula, and caffeine can still disrupt sleep.</p>
Report alternatives

Sources

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

  1. Effect of caffeine ingestion on time trial performance in cyclists: a systematic review and meta-analysis.
    Chen B; Ding L; Qin Q; Lei TH; Girard O; Cao Y · Journal of the International Society of Sports Nutrition · 2024
    Meta-analysis15 studies pooledFitness forCaffeine
  2. Effects of Caffeine Intake on Cognitive Performance Related to Total Sleep Deprivation and Time on Task: A Randomized Cross-Over Double-Blind Study.
    Quiquempoix M; Sauvet F; Erblang M; Van Beers P; Guillard M; Drogou C; Trignol A; Vergez A; Léger D; Chennaoui M; Gomez-Merino D; Rabat A · Nature and science of sleep · 2022
    Randomized trial24 participantsEnergy Productivity Boost forCaffeine
  3. 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 Cognitive Support forTheanine
  4. Caffeine administration at night during extended wakefulness effectively mitigates performance impairment but not subjective assessments of fatigue and sleepiness.
    Paech GM; Banks S; Pajcin M; Grant C; Johnson K; Kamimori GH; Vedova CB · Pharmacology, biochemistry, and behavior · 2017
    Randomized trial24 participantsEnergy forCaffeine
  5. 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
  6. Effects of Acute Caffeine Ingestion on Cognitive Performance before and after Repeated Small-Sided Games in Professional Soccer Players: A Placebo-Controlled, Randomized Crossover Trial.
    de Almeida RF; de Oliveira M; Furigo IC; Aquino R; Clarke ND; Tallis J; Guimaraes-Ferreira L · Nutrients · 2023
    Randomized trial12 participantsProductivity Boost forCaffeine
  7. No effects of caffeine on cycling to exhaustion and perceptual responses in non-caffeine-restricted subjects.
    Weippert M; Behrens M; Schlegel M; Schröder T; Tillmann M; Rühe N; Römer R; Mau-Möller A; Bruhn S · Journal of the International Society of Sports Nutrition · 2025
    Randomized trial56 participantsEnergy Fitness forCaffeine
  8. 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 Cognitive Support Productivity Boost forTheanine
  9. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood.
    Dodd FL; Kennedy DO; Riby LM; Haskell-Ramsay CF · Psychopharmacology · 2016
    Randomized trial24 participantsCognitive Support Mental Focus 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. Association of the anxiogenic and alerting effects of caffeine with ADORA2A and ADORA1 polymorphisms and habitual level of caffeine consumption.
    Rogers PJ; Hohoff C; Heatherley SV; Mullings EL; Maxfield PJ; Evershed RP; Deckert J; Nutt DJ · Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2010
    Randomized trial379 participantsProductivity Boost forCaffeine
  12. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features.
    Juliano LM; Griffiths RR · Psychopharmacology · 2005
    Systematic review66 studies pooledEnergy forCaffeine
  13. Effect of caffeine ingestion on cycling performance: a systematic review and meta-analysis.
    Wu J; Xu K; Yin M; Ding X; Wang T; Zhang Q; Wu X; Xiao N · Frontiers in nutrition · 2026
    Meta-analysis226 participants20 studies pooledFitness forCaffeine
  14. 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
  15. Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-Analysis.
    Wang Z; Qiu B; Gao J; Del Coso J · Nutrients · 2023
    Meta-analysis254 participants21 studies pooledFitness forCaffeine
  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 pooledMental Focus Cognitive Support Brain Health 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 participantsCognitive Support Brain Health forTheanine
  18. Limited Efficacy of Caffeine and Recovery Costs During and Following 5 Days of Chronic Sleep Restriction.
    Doty TJ; So CJ; Bergman EM; Trach SK; Ratcliffe RH; Yarnell AM; Capaldi VF; Moon JE; Balkin TJ; Quartana PJ · Sleep · 2018
    Clinical trial48 participantsProductivity Boost forCaffeine
  19. Differential cognitive effects of energy drink ingredients: caffeine, taurine, and glucose.
    Giles GE; Mahoney CR; Brunyé TT; Gardony AL; Taylor HA; Kanarek RB · Pharmacology, biochemistry, and behavior · 2013
    Randomized trial48 participantsEnergy forCaffeine
  20. 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
  21. Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes.
    Guest N; Corey P; Vescovi J; El-Sohemy A · Medicine and science in sports and exercise · 2019
    Randomized trial101 participantsFitness forCaffeine
  22. Effects of caffeine and glucose, alone and combined, on cognitive performance.
    Adan A; Serra-Grabulosa JM · Human psychopharmacology · 2010
    Randomized trial72 participantsProductivity Boost forCaffeine
  23. 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 Mental Focus forTheanine
  24. 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 participantsCognitive Support Stress Relief Brain Health Sleep Support forTheanine
  25. Does Single or Combined Caffeine and Taurine Supplementation Improve Athletic and Cognitive Performance without Affecting Fatigue Level in Elite Boxers? A Double-Blind, Placebo-Controlled Study.
    Ozan M; Buzdagli Y; Eyipinar CD; Baygutalp NK; Yüce N; Oget F; Kan E; Baygutalp F · Nutrients · 2022
    Randomized trial20 participantsEnergy forCaffeine
  26. Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation.
    Saunders B; de Oliveira LF; da Silva RP; de Salles Painelli V; Gonçalves LS; Yamaguchi G; Mutti T; Maciel E; Roschel H; Artioli GG; Gualano B · Scandinavian journal of medicine & science in sports · 2018
    Randomized trial42 participantsFitness forCaffeine
  27. Caffeine reversal of sleep deprivation effects on alertness and mood.
    Penetar D; McCann U; Thorne D; Kamimori G; Galinski C; Sing H; Thomas M; Belenky G · Psychopharmacology · 1995
    Randomized trial50 participantsProductivity Boost forCaffeine
  28. 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
  29. Trait Energy and Fatigue Modify the Effects of Caffeine on Mood, Cognitive and Fine-Motor Task Performance: A Post-Hoc Study.
    Fuller DT; Smith ML; Boolani A · Nutrients · 2021
    Randomized trialEnergy forCaffeine
  30. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses.
    Yoto A; Motoki M; Murao S; Yokogoshi H · Journal of physiological anthropology · 2013
    Randomized trial14 participantsStress Relief forTheanine
  31. Acute Effects of Caffeine Supplementation on Movement Velocity in Resistance Exercise: A Systematic Review and Meta-analysis.
    Raya-González J; Rendo-Urteaga T; Domínguez R; Castillo D; Rodríguez-Fernández A; Grgic J · Sports medicine (Auckland, N.Z.) · 2021
    Meta-analysis12 studies pooledFitness forCaffeine
  32. Effects of Different Sources of Low-Dose Caffeine on Mood/Arousal and Cognitive Performance.
    Irwin C; McCartney D; Grant G; Delang N; Bartrim K; Cox GR; Desbrow B · Perceptual and motor skills · 2023
    Randomized trial22 participantsProductivity Boost forCaffeine
  33. 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 Cognitive Support Brain Health Productivity Boost forTheanine
  34. Effect of Caffeine on Golf Performance and Fatigue during a Competitive Tournament.
    Mumford PW; Tribby AC; Poole CN; Dalbo VJ; Scanlan AT; Moon JR; Roberts MD; Young KC · Medicine and science in sports and exercise · 2016
    Randomized trial12 participantsEnergy forCaffeine
  35. 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
  36. Acute Effects of Caffeine Supplementation on Physical Performance, Physiological Responses, Perceived Exertion, and Technical-Tactical Skills in Combat Sports: A Systematic Review and Meta-Analysis.
    Delleli S; Ouergui I; Messaoudi H; Trabelsi K; Ammar A; Glenn JM; Chtourou H · Nutrients · 2022
    Meta-analysis26 studies pooledFitness forCaffeine
  37. Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-Analysis.
    Lorenzo Calvo J; Fei X; Domínguez R; Pareja-Galeano H · Nutrients · 2021
    Meta-analysis13 studies pooledProductivity Boost forCaffeine
  38. 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 participantsStress Relief Mood Support forTheanine
  39. Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine.
    Carvalho A; Marticorena FM; Grecco BH; Barreto G; Saunders B · Sports medicine (Auckland, N.Z.) · 2022
    Meta-analysis60 studies pooledFitness forCaffeine
  40. Effect of three caffeine doses on plasma catecholamines and alertness during prolonged wakefulness.
    Kamimori GH; Penetar DM; Headley DB; Thorne DR; Otterstetter R; Belenky G · European journal of clinical pharmacology · 2001
    Randomized trial50 participantsProductivity Boost forCaffeine
  41. Caffeine Supplementation and Physical Performance, Muscle Damage and Perception of Fatigue in Soccer Players: A Systematic Review.
    Mielgo-Ayuso J; Calleja-Gonzalez J; Del Coso J; Urdampilleta A; León-Guereño P; Fernández-Lázaro D · Nutrients · 2019
    Systematic review17 participants17 studies pooledEnergy forCaffeine
  42. 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
  43. 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 Cognitive Support forTheanine
  44. 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
  45. Sex Differences in the Ergogenic Response of Acute Caffeine Intake on Muscular Strength, Power and Endurance Performance in Resistance-Trained Individuals: A Randomized Controlled Trial.
    Montalvo-Alonso JJ; Ferragut C; Del Val-Manzano M; Valadés D; Roberts J; Pérez-López A · Nutrients · 2024
    Randomized trial76 participantsFitness forCaffeine
  46. Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine.
    Haskell CF; Kennedy DO; Wesnes KA; Scholey AB · Psychopharmacology · 2005
    Randomized trial48 participantsProductivity Boost Energy forCaffeine
  47. Effect of caffeine intake on fat oxidation rate during exercise: is there a dose-response effect?
    Gutiérrez-Hellín J; Aguilar-Navarro M; Ruiz-Moreno C; Muñoz A; Varillas-Delgado D; Amaro-Gahete FJ; Del Coso J · European journal of nutrition · 2023
    Randomized trial18 participantsEnergy Metabolism Boost forCaffeine
  48. 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 participantsStress Relief Mood Support forTheanine
  49. Caffeine-containing energy drink improves physical performance of elite rugby players during a simulated match.
    Del Coso J; Ramírez JA; Muñoz G; Portillo J; Gonzalez-Millán C; Muñoz V; Barbero-Álvarez JC; Muñoz-Guerra J · Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme · 2016
    Randomized trial26 participantsEnergy forCaffeine
  50. Effects of modafinil and caffeine on night-time vigilance of air force crewmembers: A randomized controlled trial.
    Wingelaar-Jagt YQ; Bottenheft C; Riedel WJ; Ramaekers JG · Journal of psychopharmacology (Oxford, England) · 2023
    Randomized trial32 participantsMental Focus forCaffeine
  51. Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers.
    Smith AP; Christopher G; Sutherland D · Journal of psychopharmacology (Oxford, England) · 2013
    Randomized trial70 participantsMental Focus forCaffeine
  52. Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation.
    Wesensten NJ; Killgore WD; Balkin TJ · Journal of sleep research · 2006
    Randomized trial48 participantsMental Focus forCaffeine
  53. Effects of caffeine on mood and performance: a study of realistic consumption.
    Brice CF; Smith AP · Psychopharmacology · 2003
    Clinical trial24 participantsMental Focus forCaffeine
  54. Effects of caffeine or diphenhydramine on visual vigilance.
    Fine BJ; Kobrick JL; Lieberman HR; Marlowe B; Riley RH; Tharion WJ · Psychopharmacology · 1995
    Randomized trial24 participantsMental Focus forCaffeine
  55. A Randomized Study to Examine the Ability of a Caffeine-Based Energy Drink to Impact Energy Expenditure, Fat Oxidation, and Cognitive Performance.
    Krieger J; Schrautemeier A; Hagele A; Gaige C; Mennemeyer O; Tolbert S; Iannotti J; Kerksick C; Noonan C; Mumford P · Nutrients · 2025
    Randomized trial60 participantsMetabolism Boost forCaffeine
  56. Oolong tea increases metabolic rate and fat oxidation in men.
    Rumpler W; Seale J; Clevidence B; Judd J; Wiley E; Yamamoto S; Komatsu T; Sawaki T; Ishikura Y; Hosoda K · The Journal of nutrition · 2001
    Randomized trial12 participantsMetabolism Boost forCaffeine
  57. Comparison of changes in energy expenditure and body temperatures after caffeine consumption.
    Koot P; Deurenberg P · Annals of nutrition & metabolism · 1995
    Randomized trial12 participantsMetabolism Boost forCaffeine
  58. Caffeine Increases Work Done above Critical Power, but Not Anaerobic Work.
    Silveira R; Andrade-Souza VA; Arcoverde L; Tomazini F; Sansonio A; Bishop DJ; Bertuzzi R; Lima-Silva AE · Medicine and science in sports and exercise · 2018
    Randomized trial9 participantsMetabolism Boost forCaffeine
  59. 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
  60. 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
  61. Effects of caffeine on alertness.
    Zwyghuizen-Doorenbos A; Roehrs TA; Lipschutz L; Timms V; Roth T · Psychopharmacology · 1990
    Randomized trial24 participantsProductivity Boost forCaffeine
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    Lieberman HR; Tharion WJ; Shukitt-Hale B; Speckman KL; Tulley R · Psychopharmacology · 2003
    Randomized trial68 participantsProductivity Boost forCaffeine
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    Kurdi MS; As A; Ladhad DA; Mitragotri MV; Baiju A · Indian journal of palliative care · 2024
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    Bulman A; D'Cunha NM; Marx W; Turner M; McKune A; Naumovski N · Sleep medicine reviews · 2025
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    Ferreira GA; Felippe LC; Bertuzzi R; Bishop DJ; Ramos IS; De-Oliveira FR; Lima-Silva AE · Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas · 2020
    Randomized trial20 participantsWeight Loss forCaffeine
  72. Eight Weeks of Sprint Interval Training With Adding Caffeine Ingestion Leads to Greater Improvements in Health-Related Physiological Parameters in Obese Male Adults.
    Zhiang J; Song Q · Physiological research · 2026
    Randomized trial30 participantsWeight Loss forCaffeine
  73. Caffeine treatment prevented from weight regain after calorie shifting diet induced weight loss.
    Davoodi SH; Hajimiresmaiel SJ; Ajami M; Mohseni-Bandpei A; Ayatollahi SA; Dowlatshahi K; Javedan G; Pazoki-Toroudi H · Iranian journal of pharmaceutical research : IJPR · 2014
    Non-randomized trial60 participantsWeight Loss forCaffeine
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    Tabrizi R; Saneei P; Lankarani KB; Akbari M; Kolahdooz F; Esmaillzadeh A; Nadi-Ravandi S; Mazoochi M; Asemi Z · Critical reviews in food science and nutrition · 2020
    Meta-analysis606 participants13 studies pooledWeight Loss forCaffeine