Product Image

Nitrosurge Shred Black Cherry

Jacked Factory
4.8
★ ★ ★ ★ ★
(52 ratings)
Theobromine 50 mg
Caffeine 180 mg
Theanine 90 mg
Product Image
Score74
A moderate-stimulant pre-workout led by acetyl-L-carnitine, caffeine, and theanine. Citrulline and beta-alanine are light, and BioPerine complicates medication compatibility.
How scoring works
Quantity:7 Ounce(s) • (30 servings)
Goals:
Energy
Mental Focus
Weight Loss
Metabolism Boost
Fitness
Productivity Boost

Score 74

A moderate-stimulant pre-workout led by acetyl-L-carnitine, caffeine, and theanine. Citrulline and beta-alanine are light, and BioPerine complicates medication compatibility.
How scoring works
$34.99($1.16 per serving)
iHerb
$ 0.00
iHerb
$ 34.99
Report prices

Analysis

Acetyl-L-carnitine reaches a useful 1 g, supported by 180 mg caffeine and 90 mg theanine for energy and focus. Theobromine adds 50 mg of longer-lasting stimulation.

Citrulline at 2 g and beta-alanine at 1.6 g are below the amounts found in more performance-focused pre-workouts. BioPerine at 2.5 mg may improve exposure to some compounds but can also alter medicine metabolism.

The formula is better suited to moderate stimulation and mental drive than maximal pump or endurance support. It may work for users who find 300-plus milligram caffeine products excessive, provided medication interactions are not a concern.

Who is it for
  • Adults seeking less caffeine than high-stimulus pre-workouts
  • People prioritizing energy and focus over maximal pump
  • Users without relevant BioPerine medication interactions
Best for
  • Moderate workout energy
  • Acetyl-L-carnitine and stimulant support
  • Training focus with theanine

Pros

  • Provides 1 g acetyl-L-carnitine
  • Uses a balanced caffeine-to-theanine pairing
  • Includes clearly dosed theobromine
  • Fully discloses active amounts

Cons

  • Citrulline amount is modest
  • Beta-alanine is lightly dosed
  • Theobromine extends the stimulant window
  • BioPerine may complicate medication use

Warnings

  • Count the 180 mg caffeine plus theobromine when planning total daily stimulant intake
  • Avoid late-day use because caffeine and theobromine may disrupt sleep
  • BioPerine may alter exposure to medicines processed by CYP3A4 or P-glycoprotein
  • Beta-alanine can cause temporary skin tingling

Nutrient quality

75 High impact

Caffeine, theanine, acetyl-L-carnitine, and performance ingredients provide balanced energy and focus support. Citrulline and beta-alanine are below stronger performance amounts.

.

Ingredient transparency

88 Highest impact

Individual active weights are clearly disclosed. Some extract percentages, enzyme activity, or non-active label details remain incomplete.

.

Customer satisfaction

63 Moderate impact

The supplied rating is favorable, but the feedback base is comparatively small. No complaint-level evidence was supplied to assess recurring issues or purpose-specific experiences.

.

Value for money

62 Moderate impact

The serving cost is high relative to the certainty provided by the label. Substantial ingredients help, but disclosure gaps weaken category competitiveness.

.
Report analysis

Goals

Energy
Energy
Impact
Highest effect
A+ Goal FitA Strength of SupportA CoverageA+ Formula Quality
Acetyl L-Carnitine · 1 Gram(s)Caffeine · 180 mg

Caffeine provides direct alertness, while acetyl L-carnitine supports metabolic and cognitive energy. Beta-alanine, citrulline, theobromine, and theanine broaden the formula across performance, circulation, and stimulant balance.

Theanine is paired logically with caffeine, and all major active amounts are disclosed. The combined caffeine and theobromine load may cause jitters, faster heart rate, or sleep disruption in stimulant-sensitive users.

Study evidence
Acetyl L-Carnitine Supportive 19 studies
Caffeine Supportive 68 studies
Citrulline No effect 14 studies
Theanine Not classified

No linked studies yet.

Theobromine Adverse 1 study
Mental Focus
Mental Focus
Impact
Highest effect
A Goal FitA Strength of SupportA- CoverageA- Formula Quality
Acetyl L-Carnitine · 1 Gram(s)Theanine · 90 mgCaffeine · 180 mg

Caffeine, acetyl-L-carnitine, L-theanine, and theobromine provide complementary alertness, mental-energy, and calm-focus support. Their amounts are clearly disclosed and generally substantial.

The pre-workout also includes citrulline and beta-alanine for exercise rather than cognition. A combined 180 mg caffeine dose with theobromine can cause jitteriness, a faster heartbeat, or sleep disruption in stimulant-sensitive users.

Study evidence
Acetyl L-Carnitine Supportive 7 studies
Caffeine Supportive 128 studies
Theanine Supportive 19 studies
Weight Loss
Weight Loss
Impact
Highest effect
A- Goal FitA Strength of SupportC+ CoverageA+ Formula Quality
Caffeine · 180 mg

Caffeine may modestly increase energy expenditure, while acetyl-L-carnitine and exercise ingredients can support training during a calorie deficit. The product does not address appetite, fiber intake, or dietary adherence.

Caffeine, acetyl-L-carnitine, theobromine, theanine, citrulline, and beta-alanine all have exact amounts. Theanine complements caffeine logically, although citrulline and beta-alanine are below common full performance doses. Caffeine and theobromine create a combined stimulant load that may cause rapid heartbeat, anxiety, or sleep disruption in sensitive users.

Study evidence
Caffeine Disputed 14 studies
Theanine Not classified

No linked studies yet.

Metabolism Boost
Metabolism Boost
Impact
Highest effect
A- Goal FitA- Strength of SupportB CoverageA- Formula Quality
Acetyl L-Carnitine · 1 Gram(s)Caffeine · 180 mg

Caffeine and acetyl L-carnitine directly support thermogenesis, alertness, and mitochondrial fatty-acid transport. The combination has strong goal alignment within a pre-workout setting.

Both lead actives are clearly quantified, while theanine moderates the stimulant profile. The 180 mg caffeine amount can cause jitteriness or insomnia and should not be stacked with other stimulants.

Study evidence
Acetyl L-Carnitine Adverse 1 study
Caffeine Disputed 40 studies
Fitness
Fitness
Impact
Highest effect
A- Goal FitB Strength of SupportB CoverageA- Formula Quality
Citrulline · 2 Gram(s)Beta-Alanine · 1.6 Gram(s)Caffeine · 180 mg

Citrulline, beta-alanine, caffeine, and acetyl-L-carnitine create a clear pre-workout formula for blood flow, repeated effort, and focus. Caffeine is sensibly paired with L-theanine, and every active amount is disclosed.

Citrulline and beta-alanine are below common full daily performance amounts at one scoop, so label directions allowing two scoops materially change exposure. Two scoops also double the stimulant load, which can increase jitters, sleep disruption, or cardiovascular symptoms in sensitive users.

Study evidence
Caffeine Supportive 255 studies
Citrulline Supportive 45 studies
Productivity Boost
Productivity Boost
Impact
Highest effect
A- Goal FitA- Strength of SupportB CoverageB Formula Quality
Acetyl L-Carnitine · 1 Gram(s)Acetyl L-Carnitine · 1 Gram(s)Theanine · 90 mgCaffeine · 180 mg

Caffeine, theanine, and acetyl-L-carnitine create a strong acute alertness and focus stack. The roughly two-to-one caffeine-to-theanine pairing may improve energy while moderating tension.

Amounts are fully disclosed, and the cognitive actives reach meaningful levels. Caffeine and theobromine can still cause jitters, rapid heartbeat, or sleep disruption, while beta-alanine may cause harmless tingling.

Study evidence
Acetyl L-Carnitine Supportive 1 study
Acetyl L-Carnitine Supportive 1 study
Caffeine Supportive 108 studies
Theanine Supportive 5 studies
Muscle Gain
Muscle Gain
Impact
Moderate effect
C+ Goal FitC- Strength of SupportC- CoverageB- Formula Quality
Caffeine · 180 mgCitrulline · 2 Gram(s)Beta-Alanine · 1.6 Gram(s)

Citrulline, beta-alanine, and caffeine may support workout performance, but the formula is not strongly dosed for hypertrophy-related training volume. The ingredients have established performance roles, although the amounts limit transfer to meaningful muscle-gain outcomes.

Citrulline and beta-alanine are below common full performance targets at the stated serving. The ingredients form a reasonable light pre-workout combination. The combined stimulants may cause jitteriness or interfere with sleep in sensitive users.

Study evidence
Caffeine Supportive 31 studies
Citrulline Supportive 15 studies

Ingredients

IngredientAmount per serving
L-Citrulline
2 Gram(s)
Beta-Alanine
1.6 Gram(s)
Acetyl-L-Carnitine (Acetyl-L-Carnitine HCl)
 1 Gram(s)
Caffeine Anhydrous
180 mg
L-Theanine
90 mg
Theobromine
50 mg
Bioperine Black Pepper fruit extract
2.5 mg
Adults 18–50 Women
Report overview
Theobromine · 50 mg OverallScore85
A+ Active Ingredient Quality & BioavailabilityB+ Dose, Safety & Label TransparencyC Value

Standalone theobromine is clearly disclosed, but the amount is aimed more at sensitive users or a stimulant stack than at strong theobromine-focused effects. Caffeine and other performance ingredients provide most of the pre-workout impact, which also raises the combined stimulant load. Serving cost is close to the collection benchmark, while the supplied details do not establish a purity percentage or fully describe flavor-system excipients.

View ingredientView products
Caffeine · 180 mg OverallScore78
B Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyD- Value

Caffeine anhydrous is clearly disclosed at 180 mg, giving the pre-workout a moderate primary stimulant dose. Theobromine adds a smaller, clearly measured stimulant load, but no sustained-release technology is present. An above-median serving cost places it in the premium-priced tier.

View ingredientView products
Theanine · 90 mg OverallScore70
B+ Active Ingredient Quality & BioavailabilityA- Dose, Safety & Label TransparencyF Value

Explicit L-theanine identity confirms the active isomer, but no branded source or purity testing is shown. The clearly disclosed amount is suited to mild support but sits below the optimal range. The caffeine-heavy pre-workout setting makes theanine a balancing ingredient rather than the main active.

View ingredientView products
Loading alternative details
84 Performance

L-Theanine & Caffeine

SR Sports Research
<p>Its label clearly provides 0.50 g of Total Fat, making it a more clearly defined caffeine and theanine option. Compared with the original, its ingredient and goal alignment is stronger, although it does not retain the original product’s theobromine coverage.</p>
84 Performance

Smart Caffeine with L-Theanine

NS Natural Stacks
<p>Its label clearly provides 200 mg of L-Theanine, making it a more clearly defined caffeine and theanine option. Compared with the original, its ingredient and goal alignment is stronger, although it does not retain the original product’s theobromine coverage.</p>
73 Performance

Nitrosurge Shred Fruit Punch

Jacked Factory JF
<p>Its label clearly provides 1 g of Acetyl-L-Carnitine as Acetyl-L-Carnitine HCl and 2.50 mg of Bioperine Black Pepper fruit extract, making it a more clearly defined caffeine and theobromine option. Compared with the original, its ingredient and goal alignment is stronger, although it does not retain the original product’s theanine coverage.</p>
70 Budget

Energy + Focus

ZHOU
<p>Its label clearly provides 200 mg of L-Theanine, preserving relevant caffeine and theanine coverage. Compared with the original, it lowers the serving cost, although it does not retain the original product’s theobromine coverage.</p>
71 Budget

Kre-Alkalyn Hardcore

All American EFX Sports
<p>Its label clearly provides 2000 mg of Kre-Alkalyn, preserving relevant caffeine and theobromine coverage. Compared with the original, it lowers the serving cost, although it does not retain the original product’s theanine coverage.</p>
83 Budget

Pure Energy

Swanson
<p>Its label clearly provides 100 mg of Naturally sourced Caffeine, preserving relevant caffeine and theanine coverage. Compared with the original, it lowers the serving cost, although it does not retain the original product’s theobromine coverage.</p>
74 Value

Hydroxycut Hardcore Elite

MuscleTech Performance Series
<p>Its label clearly provides 270 mg of Caffeine Anhydrous, keeping the formula relevant to caffeine and theanine. Compared with the original, the lower serving cost and ingredient detail create a useful quality-to-cost balance, although it does not retain the original product’s theobromine coverage.</p>
82 Value

Elite

Eu Natural
<p>Its label clearly provides 100 mg of Caffeine, keeping the formula relevant to caffeine and theanine. Compared with the original, the lower serving cost and ingredient detail create a useful quality-to-cost balance, although it does not retain the original product’s theobromine coverage.</p>
83 Value

TheanineUP Focused Energy

California Gold Nutrition
<p>Its label clearly provides 100 mg of L-Theanine, keeping the formula relevant to caffeine and theanine. Compared with the original, the lower serving cost and ingredient detail create a useful quality-to-cost balance, although it does not retain the original product’s theobromine coverage.</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. Sleep symptoms associated with intake of specific dietary nutrients.
    Grandner MA; Jackson N; Gerstner JR; Knutson KL · Journal of sleep research · 2014
    Cross-sectional study4,552 participantsEnergy forTheobromine
  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. 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
  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 participantsMental Focus forTheanine
  10. 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
  11. 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 forTheanine
  12. 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
  13. 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
  14. 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
  15. 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 forTheanine
  16. 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
  17. 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
  18. 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 forTheanine
  19. 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
  20. 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
  21. 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 Productivity Boost forTheanine
  22. 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
  23. 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
  24. Safety and Efficacy of AlphaWave® L-Theanine Supplementation for 28 Days in Healthy Adults with Moderate Stress: A Randomized, Double-Blind, Placebo-Controlled Trial.
    Moulin M; Crowley DC; Xiong L; Guthrie N; Lewis ED · Neurology and therapy · 2024
    Randomized trial30 participantsMental Focus Productivity Boost forTheanine
  25. 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
  26. 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
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. Oral acetyl-L-carnitine therapy reduces fatigue in overt hepatic encephalopathy: a randomized, double-blind, placebo-controlled study.
    Malaguarnera M; Vacante M; Giordano M; Pennisi G; Bella R; Rampello L; Malaguarnera M; Li Volti G; Galvano F · The American journal of clinical nutrition · 2011
    Randomized trial121 participantsEnergy forAcetyl L-Carnitine
  33. The supplementation of acetyl-L-carnitine decreases fatigue and increases quality of life in patients with hepatitis C treated with pegylated interferon-α 2b plus ribavirin.
    Malaguarnera M; Vacante M; Bertino G; Neri S; Malaguarnera M; Gargante MP; Motta M; Lupo L; Chisari G; Bruno CM; Pennisi G; Bella R · Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research · 2012
    Randomized trial60 participantsEnergy forAcetyl L-Carnitine
  34. Acetyl-L-carnitine reduces depression and improves quality of life in patients with minimal hepatic encephalopathy.
    Malaguarnera M; Bella R; Vacante M; Giordano M; Malaguarnera G; Gargante MP; Motta M; Mistretta A; Rampello L; Pennisi G · Scandinavian journal of gastroenterology · 2011
    Randomized trial67 participantsEnergy forAcetyl L-Carnitine
  35. A prospective study to evaluate the efficacy and safety of oral acetyl-L-carnitine for the treatment of chemotherapy-induced peripheral neuropathy.
    Sun Y; Shu Y; Liu B; Liu P; Wu C; Zheng R; Zhang X; Zhuang Z; Deng Y; Zheng L; Xu Q; Jiang B; Ouyang X; Gao J; Xu N; Li X; Jiang S; Liang C; Yao Y · Experimental and therapeutic medicine · 2020
    Randomized trial239 participantsEnergy forAcetyl L-Carnitine
  36. Metabolomic biomarkers for (R, S)-ketamine and (S)-ketamine in treatment-resistant depression and healthy controls: A systematic review.
    Kumar R; Nuñez NA; Joshi N; Joseph B; Verde A; Seshadri A; Cuellar Barboza AB; Prokop LJ; Medeiros GC; Singh B · Bipolar disorders · 2024
    Systematic reviewEnergy forAcetyl L-Carnitine
  37. 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
  38. 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
  39. Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis.
    Vårvik FT; Bjørnsen T; Gonzalez AM · International journal of sport nutrition and exercise metabolism · 2021
    Meta-analysis137 participants8 studies pooledEnergy forCitrulline
  40. Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study.
    Suzuki T; Morita M; Kobayashi Y; Kamimura A · Journal of the International Society of Sports Nutrition · 2016
    Randomized trial22 participantsEnergy forCitrulline
  41. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness.
    Pérez-Guisado J; Jakeman PM · Journal of strength and conditioning research · 2010
    Randomized trial41 participantsEnergy forCitrulline
  42. Citrulline/malate promotes aerobic energy production in human exercising muscle.
    Bendahan D; Mattei JP; Ghattas B; Confort-Gouny S; Le Guern ME; Cozzone PJ · British journal of sports medicine · 2002
    Single-arm trial18 participantsEnergy forCitrulline
  43. The Effect of Citrulline Malate Supplementation on Muscle Fatigue Among Healthy Participants.
    Farney TM; Bliss MV; Hearon CM; Salazar DA · Journal of strength and conditioning research · 2019
    Randomized trial12 participantsEnergy forCitrulline
  44. 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
  45. 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
  46. 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
  47. 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
  48. 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
  49. The Effects of Combined Exercise with Citrulline Supplementation on Body Composition and Lower Limb Function of Overweight Older Adults: A Systematic Review and Meta-Analysis.
    Xie S; Li S; Shaharudin S · Journal of sports science & medicine · 2023
    Meta-analysis303 participants7 studies pooledFitness forCitrulline
  50. Effect of High-Intensity Interval Training Combined with L-Citrulline Supplementation on Functional Capacities and Muscle Function in Dynapenic-Obese Older Adults.
    Buckinx F; Gouspillou G; Carvalho LP; Marcangeli V; El Hajj Boutros G; Dulac M; Noirez P; Morais JA; Gaudreau P; Aubertin-Leheudre M · Journal of clinical medicine · 2020
    Randomized trial56 participantsFitness Muscle Gain forCitrulline
  51. Initial Dietary Protein Intake Influence Muscle Function Adaptations in Older Men and Women Following High-Intensity Interval Training Combined with Citrulline.
    Buckinx F; Marcangeli V; Pinheiro Carvalho L; Dulac M; Hajj Boutros G; Gouspillou G; Gaudreau P; Morais J; Noirez P; Aubertin-Leheudre M · Nutrients · 2020
    Randomized trial73 participantsFitness forCitrulline
  52. Effects of Citrulline alone or combined with exercise on muscle mass, muscle strength, and physical performance among older adults: a systematic review.
    Aubertin-Leheudre M; Buckinx F · Current opinion in clinical nutrition and metabolic care · 2021
    Systematic review250 participants6 studies pooledFitness Muscle Gain forCitrulline
  53. Combined Vs. Single Supplementation of L-Citrulline and Sodium Bicarbonate During Sprint Interval Training in Basketball Players: Effects on Physical Performance and Hormonal Adaptations.
    Wang Y; Wang Y; Qian K · Journal of sports science & medicine · 2025
    Randomized trial40 participantsFitness forCitrulline
  54. Acetyl-L-carnitine in the treatment of mildly demented elderly patients.
    Passeri M; Cucinotta D; Bonati PA; Iannuccelli M; Parnetti L; Senin U · International journal of clinical pharmacology research · 1990
    Randomized trial60 participantsMental Focus forAcetyl L-Carnitine
  55. Acetyl-L-Carnitine Supplementation During HCV Therapy With Pegylated Interferon-α 2b Plus Ribavirin: Effect on Work Performance; A Randomized Clinical Trial.
    Malaguarnera G; Pennisi M; Gagliano C; Vacante M; Malaguarnera M; Salomone S; Drago F; Bertino G; Caraci F; Nunnari G; Malaguarnera M · Hepatitis monthly · 2014
    Randomized trial62 participantsMental Focus Productivity Boost forAcetyl L-Carnitine
  56. [Psycho-functional changes in attention and learning under the action of L-acetylcarnitine in 17 young subjects. A pilot study of its use in mental deterioration].
    Lino A; Boccia MM; Rusconi AC; Bellomonte L; Cocuroccia B · La Clinica terapeutica · 1992
    Non-randomized trial17 participantsMental Focus forAcetyl L-Carnitine
  57. Acetyl-L-carnitine (ALC) in attention-deficit/hyperactivity disorder: a multi-site, placebo-controlled pilot trial.
    Arnold LE; Amato A; Bozzolo H; Hollway J; Cook A; Ramadan Y; Crowl L; Zhang D; Thompson S; Testa G; Kliewer V; Wigal T; McBurnett K; Manos M · Journal of child and adolescent psychopharmacology · 2008
    Randomized trial112 participantsMental Focus forAcetyl L-Carnitine
  58. Acetyl-L-carnitine for patients with hepatic encephalopathy.
    Martí-Carvajal AJ; Gluud C; Arevalo-Rodriguez I; Martí-Amarista CE · The Cochrane database of systematic reviews · 2019
    Meta-analysis398 participants5 studies pooledMental Focus forAcetyl L-Carnitine
  59. 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
  60. Effects of caffeine on mood and performance: a study of realistic consumption.
    Brice CF; Smith AP · Psychopharmacology · 2003
    Clinical trial24 participantsMental Focus forCaffeine
  61. 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
  62. Low Bioavailability and High TMAO Production: Novel Insights Into Acetylcarnitine and Carnitine Metabolism.
    Krims-Davis K; Ozola M; Razzivina V; Gukalova B; Konrade I; Dambrova M; Liepinsh E · Molecular nutrition & food research · 2025
    Randomized trialMetabolism Boost forAcetyl L-Carnitine
  63. 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
  64. 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
  65. 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
  66. 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
  67. Effects of Acute Ingestion of Caffeine Capsules on Muscle Strength and Muscle Endurance: A Systematic Review and Meta-Analysis.
    Wu W; Chen Z; Zhou H; Wang L; Li X; Lv Y; Sun T; Yu L · Nutrients · 2024
    Meta-analysis14 studies pooledMuscle Gain forCaffeine
  68. Acute caffeine intake improves muscular strength, power, and endurance performance, reversing the time-of-day effect regardless of muscle activation level in resistance-trained males: a randomized controlled trial.
    Montalvo-Alonso JJ; Del Val-Manzano M; Cerezo-Telléz E; Ferragut C; Valadés D; Rodríguez-Falces J; Pérez-López A · European journal of applied physiology · 2025
    Randomized trial13 participantsMuscle Gain forCaffeine
  69. Wake up and smell the coffee: caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses.
    Grgic J; Grgic I; Pickering C; Schoenfeld BJ; Bishop DJ; Pedisic Z · British journal of sports medicine · 2020
    Systematic review21 studies pooledMuscle Gain forCaffeine
  70. Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis.
    Grgic J; Trexler ET; Lazinica B; Pedisic Z · Journal of the International Society of Sports Nutrition · 2018
    Meta-analysis20 studies pooledMuscle Gain forCaffeine
  71. Caffeine increases strength and power performance in resistance-trained females during early follicular phase.
    Norum M; Risvang LC; Bjørnsen T; Dimitriou L; Rønning PO; Bjørgen M; Raastad T · Scandinavian journal of medicine & science in sports · 2021
    Randomized trial15 participantsMuscle Gain forCaffeine
  72. Impact of L-citrulline supplementation and whole-body vibration training on arterial stiffness and leg muscle function in obese postmenopausal women with high blood pressure.
    Figueroa A; Alvarez-Alvarado S; Ormsbee MJ; Madzima TA; Campbell JC; Wong A · Experimental gerontology · 2015
    Randomized trial41 participantsMuscle Gain forCitrulline
  73. Citrulline Supplementation Improves Microvascular Function and Muscle Strength in Middle-Aged and Older Adults with Type 2 Diabetes.
    Figueroa A; Dillon KN; Levitt DE; Kang Y · Nutrients · 2025
    Randomized trial16 participantsMuscle Gain forCitrulline
  74. Citrulline stimulates muscle protein synthesis in the post-absorptive state in healthy people fed a low-protein diet - A pilot study.
    Jourdan M; Nair KS; Carter RE; Schimke J; Ford GC; Marc J; Aussel C; Cynober L · Clinical nutrition (Edinburgh, Scotland) · 2016
    Randomized trial8 participantsMuscle Gain forCitrulline
  75. Effects of caffeine on alertness.
    Zwyghuizen-Doorenbos A; Roehrs TA; Lipschutz L; Timms V; Roth T · Psychopharmacology · 1990
    Randomized trial24 participantsProductivity Boost forCaffeine
  76. 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
  77. 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
  78. 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
  79. 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
  80. 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
  81. 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
  82. 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
    Cohort study58,157 participantsWeight Loss forCaffeine
  83. Does caffeine ingestion before a short-term sprint interval training promote body fat loss?
    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
  84. 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
  85. 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
  86. 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