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L-Theanine & Caffeine

SR Sports Research
4.5
★ ★ ★ ★ ★
(4226 ratings)
Theanine 200 mg
Caffeine 100 mg
Product Image
Score84
A balanced green-coffee caffeine and theanine softgel offers strong value for daytime focus. It remains a conventional stimulant without controlled release.
How scoring works
Quantity:60 Softgel(s) • (60 servings)
Goals:
Mental Focus
Productivity Boost
Cognitive Support
Energy
Brain Health
Fitness
Weight Loss
Metabolism Boost
Stress Relief
Mood Support

Score 84

A balanced green-coffee caffeine and theanine softgel offers strong value for daytime focus. It remains a conventional stimulant without controlled release.
How scoring works
$22.95($0.38 per serving)
iHerb
$ 22.97
Amazon
$ 22.95
Vitacost
$ 23.97
Walmart
$ 22.95
Report prices

Analysis

PurCaf green-coffee caffeine at 100 mg supplies moderate stimulation, paired with 200 mg L-theanine for calm alertness. Both active amounts are clear and use a practical two-to-one balance.

MCT oil supports the softgel delivery but is not a meaningful cognitive active at 500 mg. The formula is strongest for short-term attention and energy, not sleep or long-term brain structure.

One softgel and low serving cost create excellent convenience and value. The caffeine is not controlled release, and theanine sourcing and independent testing are not supplied.

Who is it for
  • Adults seeking moderate alertness
  • People wanting green-coffee caffeine with theanine
  • Users who prefer softgels
Best for
  • Daytime focus
  • Productivity
  • Pre-workout alertness

Pros

  • Provides 200 mg L-theanine
  • Uses 100 mg PurCaf caffeine
  • Convenient one-softgel serving
  • Low serving cost

Cons

  • No controlled-release caffeine
  • Generic theanine source
  • No independent testing details
  • Poor fit for bedtime use

Warnings

  • Caffeine may cause jitteriness, faster heartbeat, anxiety, or sleep disruption
  • Avoid taking late in the day
  • Count other caffeine sources toward total daily intake

Nutrient quality

91 Highest impact

L-theanine and green-coffee-sourced caffeine are clearly identified, although no controlled-release feature is present. Theanine and caffeine use 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

67 High 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 oil carrier adds little active value but does not materially dilute the focused formula.

.
Report analysis

Goals

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

L-theanine with caffeine is a well-matched combination for calm alertness and sustained attention. Both actives are supplied at meaningful, clearly disclosed amounts.

Theanine may smooth caffeine-related tension while caffeine supplies immediate vigilance. Sensitive users should avoid late-day use because the caffeine may cause jitters, a faster heartbeat, or sleep disruption.

Study evidence
Caffeine Supportive 128 studies
Theanine Supportive 19 studies
Productivity Boost
Productivity Boost
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 combination for alertness with smoother attention. The 100 mg caffeine and 200 mg theanine amounts create a practical balance.

The blend targets both acute wakefulness and control of stimulant tension, making it directly useful for focused work. MCT oil is not essential to the cognitive effect but does not materially distract from the formula.

Study evidence
Caffeine Supportive 108 studies
Theanine Supportive 5 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-supported pairing for alertness with calmer focus. The disclosed amounts use a balanced ratio that may reduce some caffeine-related tension.

MCT oil supports softgel delivery but is not a cognitive active at this amount. The 100 mg caffeine dose may cause jitters, a faster heartbeat, or sleep disruption in sensitive users, especially when taken late.

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

Caffeine provides reliable alertness while L-theanine may support calmer focus. The 100 mg caffeine and 200 mg L-theanine amounts form a well-balanced and clearly disclosed pairing.

The design is focused on immediate mental energy rather than mitochondrial output or long-term resilience. Caffeine may still cause jitteriness, a faster heartbeat, or sleep disruption, particularly when combined with coffee or other stimulants.

Study evidence
Caffeine Supportive 68 studies
Theanine Not classified

No linked studies yet.

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

L-theanine and caffeine form a well-established pairing for alert focus, with theanine helping smooth the stimulant response. The clearly disclosed amounts are well balanced for an acute cognitive effect rather than long-term structural brain support.

The simple combination provides strong depth in attention and alertness without unrelated ingredients. The caffeine may cause jitters, a faster heartbeat, anxiety, or sleep disruption in sensitive users.

Study evidence
Theanine Supportive 17 studies
Fitness
Fitness
Impact
Highest effect
A- Goal FitA- Strength of SupportC+ CoverageA+ Formula Quality
Caffeine · 100 mg

Caffeine provides acute alertness and lower perceived exertion, while L-theanine may smooth the mental edge. The disclosed amounts form a practical focus-oriented pre-workout pairing.

The formula does not support muscle repair, ATP regeneration, or hydration. The 100 mg caffeine amount can still disturb sleep when taken late or cause jitters in sensitive users.

Study evidence
Caffeine Supportive 255 studies

Ingredients

IngredientAmount per serving
Calories
5 Calorie(s)
Total Fat
0.5 Gram(s)
Medium Chain Triglycerides (Coconut)
 500 mg
L-Theanine
200 mg
PurCaf Caffeine (Green Coffee)
 100 mg
Gluten Free Adults 18–50
Report overview
Theanine · 200 mg OverallScore92
B+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyA+ Value

Explicit L-Theanine at a well-aligned dose is paired with caffeine for alertness and focused energy. The active amount is clear, but no branded theanine source, purity claim, or independent testing detail is provided. The combination offers strong cost efficiency, although the caffeine may cause jitters, sleep disruption, or a faster heartbeat in 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 sits in the target range and is paired with L-theanine rather than another stimulant. Green-coffee sourcing is identified, but no caffeine standardization or controlled-release feature is provided. The low serving cost gives the formula excellent economic efficiency.

View ingredientView products
Loading alternative details
83 Performance

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, giving a clearer or more purpose-specific option than 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>
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>
85 Performance

L-Theanine 150 mg

Solgar
<p>A 150 mg Suntheanine serving provides a meaningful branded amount for calm focus in a streamlined formula, giving a clearer or more purpose-specific option than the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. It removes caffeine, trading immediate energy for a lower-stimulation approach.</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>
84 Value

L-Theanine 200 mg

Advance Physician Formulas
<p>A focused 200 mg L-theanine serving provides a practical amount for calm attention and relaxation at an equal or lower serving cost compared with the original clear pairing of 200 mg theanine with 100 mg green-coffee caffeine. No branded source or purity marker is supplied, and the caffeine-free design will not provide an energy lift.</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
  63. 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
  64. Changes in caffeine intake and long-term weight change in men and women.
    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
    Non-randomized trial60 participantsWeight Loss forCaffeine
  68. The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials.
    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