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Energy + Focus

ZHOU
4.1
★ ★ ★ ★ ★
(265 ratings)
Theanine 200 mg
Caffeine 100 mg
Product Image
Score70
Useful theanine and low cost support daytime focus. Ambiguous repeated caffeine amounts are a serious clarity and safety drawback.
How scoring works
Quantity:60 Capsule(s) • (60 servings)
Goals:
Brain Health
Cognitive Support
Mental Focus
Energy
Mood Support
Productivity Boost
Metabolism Boost
Fitness
Weight Loss
Stress Relief

Score 70

Useful theanine and low cost support daytime focus. Ambiguous repeated caffeine amounts are a serious clarity and safety drawback.
How scoring works
$20.89($0.34 per serving)
Pure Formulas
$ 20.89
iHerb
$ 20.89
Vitacost
$ 20.89
Daily Vita
$ 24.00
Report prices

Analysis

L-theanine at 200 mg is well aligned with calm-focus use. Caffeine is listed through anhydrous, robusta, and arabica entries, each showing 100 mg, which makes the combined amount unclear.

If the entries describe one shared caffeine total, the ratio is practical; if additive, the serving is highly stimulating. The ambiguity prevents confident use and matters more than the simple ingredient list suggests.

One capsule and low cost are appealing for daytime focus. The product is not suitable for sleep support, and caffeine-sensitive users should treat the label conservatively.

Who is it for
  • Caffeine-tolerant adults seeking focused energy
  • People wanting theanine with caffeine
  • Users able to clarify the total caffeine amount
Best for
  • Daytime alertness
  • Mental focus
  • Productivity support

Pros

  • Provides 200 mg L-theanine
  • Lists caffeine sources
  • One-capsule serving
  • Low serving cost

Cons

  • Total caffeine amount is ambiguous
  • No long-term cognitive support
  • Generic theanine source
  • Poor sleep fit

Warnings

  • Treat the repeated caffeine entries as potentially additive unless the label confirms otherwise
  • Caffeine may cause jitteriness, palpitations, anxiety, or sleep disruption
  • Avoid combining with other caffeine or stimulant products
  • Do not take late in the day

Nutrient quality

69 High impact

L-theanine and caffeine anhydrous are usable forms, while duplicated botanical caffeine entries create uncertainty. Theanine is meaningful, but the combined caffeine amount is ambiguous and may be aggressive.

.

Ingredient transparency

70 High 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

57 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

83 Highest impact

Useful active delivery supports favorable serving value. The formula is conceptually focused, although repeated caffeine entries add unclear complexity.

.
Report analysis

Goals

Brain Health
Brain Health
Impact
Highest effect
A- Goal FitA Strength of SupportB+ CoverageA+ Formula Quality

L-theanine and caffeine form a well-matched combination for alert but calmer focus. Both active amounts are clearly disclosed and sit in practical ranges.

The formula is useful for short-term attention but does not address memory, membranes, circulation, or long-term neuroprotection. Caffeine may cause jitteriness, rapid heartbeat, or sleep disruption in 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

L-theanine and caffeine form a well-matched combination for alert but calmer focus. Both active amounts are clearly disclosed and sit in practical ranges.

The formula is useful for short-term attention but does not address memory, membranes, circulation, or long-term neuroprotection. Caffeine may cause jitteriness, rapid heartbeat, or sleep disruption in sensitive users.

Study evidence
Theanine Supportive 25 studies
Mental Focus
Mental Focus
Impact
Highest effect
A+ Goal FitB+ Strength of SupportC+ CoverageA Formula Quality
Theanine · 200 mgCaffeine · 100 mg

Caffeine and L-theanine form a well-established calm-alertness pairing that can support attention and reaction time. Theanine may soften caffeine-related tension while preserving the acute stimulant effect.

The theanine amount is clearly disclosed, but multiple quantified caffeine-source entries make the total stimulant exposure harder to interpret. Strong caffeine exposure may cause jitteriness, a faster heart rate, anxiety, or sleep disruption in sensitive users.

Study evidence
Caffeine Supportive 128 studies
Theanine Supportive 19 studies
Energy
Energy
Impact
Highest effect
A+ Goal FitB- Strength of SupportC+ CoverageA+ Formula Quality
Caffeine · 100 mg

Caffeine and theanine form a well-supported pairing for alertness with a smoother subjective effect than caffeine alone. The serving clearly supplies enough of both actives to make an acute difference.

The label repeats the same caffeine amount across anhydrous, robusta, and arabica sources, so total stimulant exposure is not fully clear. Caffeine may cause jitteriness, palpitations, anxiety, or sleep disruption, particularly if the repeated entries represent additive amounts.

Study evidence
Caffeine Supportive 68 studies
Theanine Not classified

No linked studies yet.

Mood Support
Mood Support
Impact
Highest effect
B- Goal FitA+ Strength of SupportB- CoverageA+ Formula Quality

L-theanine and caffeine create a well-established calm-alertness pairing that may help short-term mood under pressure. Both active amounts are clearly disclosed and fall within practical ranges.

The formula is more suited to energy and focus than ongoing mood regulation. The 100 mg caffeine amount may cause jitteriness, faster heartbeat, or sleep disruption in sensitive users, which can worsen anxious mood.

Study evidence
Theanine Supportive 12 studies
Productivity Boost
Productivity Boost
Impact
Highest effect
A+ Goal FitC+ Strength of SupportB- CoverageA Formula Quality
Theanine · 200 mgCaffeine · 100 mg

Caffeine and L-theanine form one of the clearest productivity pairings, combining alertness with a calmer attention profile. Both actives are supplied at practical amounts.

The multiple caffeine entries make the total serving harder to interpret, even though the accompanying analysis indicates a strong dose. Caffeine-sensitive users may experience jitteriness or sleep disruption, especially when taken late in the day.

Study evidence
Caffeine Supportive 108 studies
Theanine Supportive 5 studies

Ingredients

IngredientAmount per serving
L-Theanine
200 mg
natural Caffeine (Caffeine Anhydrous, Coffea canephora, Coffee arabica)
 100 mg
Gluten Free Adults 18–50 Dairy Free
Report overview
Theanine · 200 mg OverallScore88
B+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyB+ Value

The formula provides a full-range L-Theanine dose in a clear, simple capsule. No branded source or added purity evidence is supplied, but the active isomer is correctly identified. Cost efficiency is competitive, while 100 mg of caffeine may cause jitteriness or sleep disruption in sensitive users.

View ingredientView products
Caffeine (Caffeine Anhydrous, Coffea canephora, Coffee arabica) · 100 mg OverallScore75
B Active Ingredient Quality & BioavailabilityB- Dose, Safety & Label TransparencyB+ Value

The clearly identified anhydrous caffeine supports reliable absorption, while the accompanying theanine may soften the stimulant feel for some users. Multiple caffeine entries require the user to interpret the combined dose, which appears strong for one serving. The low serving cost supports good value, but caffeine-sensitive users may prefer a milder dose.

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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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 formula with 200 mg theanine and three separate 100 mg caffeine entries that make total stimulant exposure unclear. 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. Using coffee to compensate for poor sleep: Impact on vigilance and implications for workplace performance.
    Anderson JR; Hagerdorn PL; Gunstad J; Spitznagel MB · Applied ergonomics · 2018
    Randomized trial69 participantsMental Focus forCaffeine
  2. 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
  3. 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
  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 forTheanine
  5. 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 forCaffeine
  6. Physiological and cognitive responses to caffeine during repeated, high-intensity exercise.
    Crowe MJ; Leicht AS; Spinks WL · International journal of sport nutrition and exercise metabolism · 2007
    Randomized trial17 participantsMental Focus forCaffeine
  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. 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
  9. 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
  10. 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 participantsMental Focus forTheanine
  11. Caffeinated Coffee and Tea Consumption, Genetic Variation and Cognitive Function in the UK Biobank.
    Cornelis MC; Weintraub S; Morris MC · The Journal of nutrition · 2020
    Cross-sectional study445,786 participantsMental Focus forCaffeine
  12. 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
  13. 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 Brain Health Cognitive Support forTheanine
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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 participantsStress Relief Brain Health Cognitive Support forTheanine
  21. The effects of L-theanine, caffeine and their combination on cognition and mood.
    Haskell CF; Kennedy DO; Milne AL; Wesnes KA; Scholey AB · Biological psychology · 2008
    Randomized trialMental Focus forCaffeine
  22. 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
  23. 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
  24. 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
  25. Caffeine and attentional control: improved and impaired performance in healthy older adults and Parkinson's disease according to task demands.
    Sharma K; Fallon SJ; Davis T; Ankrett S; Munro G; Christopher G; Coulthard E · Psychopharmacology · 2022
    Randomized trial68 participantsMental Focus forCaffeine
  26. 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
  27. 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
  28. 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
  29. The combined effects of L-theanine and caffeine on cognitive performance and mood.
    Owen GN; Parnell H; De Bruin EA; Rycroft JA · Nutritional neuroscience · 2009
    Randomized trial27 participantsMental Focus forCaffeine
  30. 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 forCaffeine
  31. 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
  32. The effect of mouth rinsing with different concentrations of caffeine solutions on reaction time.
    Virdinli SG; Kutlay E; Yuzbasioglu Y; Vollaard NBJ; Rudarli Nalcakan G · Journal of sports sciences · 2022
    Randomized trial45 participantsMental Focus forCaffeine
  33. 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
  34. 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
  35. 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
  36. Caffeine attenuates scopolamine-induced memory impairment in humans.
    Riedel W; Hogervorst E; Leboux R; Verhey F; van Praag H; Jolles J · Psychopharmacology · 1996
    Randomized trial16 participantsMental Focus forCaffeine
  37. 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
  38. 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
  39. 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
  40. 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
  41. 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 participantsEnergy forCaffeine
  42. 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
  43. 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
  44. 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
  45. 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
  46. 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
  47. 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
  48. 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
  49. Effects of caffeine on mood and performance: a study of realistic consumption.
    Brice CF; Smith AP · Psychopharmacology · 2003
    Clinical trial24 participantsMental Focus forCaffeine
  50. 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
  51. 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
  52. 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
  53. 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
  54. 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
  55. 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
  56. 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
  57. Effects of caffeine on alertness.
    Zwyghuizen-Doorenbos A; Roehrs TA; Lipschutz L; Timms V; Roth T · Psychopharmacology · 1990
    Randomized trial24 participantsProductivity Boost forCaffeine
  58. 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
  59. Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Sea-Air-Land.
    Lieberman HR; Tharion WJ; Shukitt-Hale B; Speckman KL; Tulley R · Psychopharmacology · 2003
    Randomized trial68 participantsProductivity Boost forCaffeine
  60. A review of caffeine's effects on cognitive, physical and occupational performance.
    McLellan TM; Caldwell JA; Lieberman HR · Neuroscience and biobehavioral reviews · 2017
    Narrative reviewProductivity Boost forCaffeine
  61. Acute caffeine supplementation as a nutrition-based strategy to mitigate sleep-loss-related cognitive and operational performance impairments in military personnel: a systematic review and meta-analysis.
    Wang R; Wang W; Meng L; Hao G; Gu G · Frontiers in nutrition · 2026
    Meta-analysis7 studies pooledProductivity Boost forCaffeine
  62. 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
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    Cotter J; Kilpatrick HE · Frontiers in nutrition · 2026
    Narrative reviewProductivity Boost forTheanine
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    Lopez-Garcia E; van Dam RM; Rajpathak S; Willett WC; Manson JE; Hu FB · The American journal of clinical nutrition · 2006
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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
  66. 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
  67. 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
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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