Caffeine

L-theanine smooths out caffeine's edge

Alert focus without jitteriness; the 'smart caffeine' stack

⟡ Creatine

Different mechanisms for performance

Caffeine for endurance/alertness, creatine for power output

⊕ Alpha-GPC

stacks-well

Common nootropic stack for focus

Enhanced alertness and cognitive performance

⟡ BCAAs

Common pre-workout combination

BCAAs for muscle support, caffeine for energy and focus

✦ Green Tea Extract

Classic combination for fat oxidation

Enhanced thermogenic and cognitive effects

⟡ MCT Oil

Popular combination for energy and focus

Enhanced alertness and sustained energy

⟡ Sodium Bicarbonate

Different ergogenic mechanisms

Additive performance benefits

⟡ Theacrine

Enhanced and prolonged energy when combined

Faster onset (caffeine) with sustained energy (theacrine)

⟡ Tyrosine

Both support alertness through different mechanisms

Enhanced mental performance; start with lower doses of each

Top studies from 40+ peer-reviewed papers

📚meta-analysisn=2020

Collado-Mateo D et al. • Nutrients (2020)

“However, the fitness level of the participant may modulate the magnitude of the effect of caffeine on fat oxidation during exercise.”

Key Findings:

A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The meta-analysis revealed that caffeine significantly (p = 0.008) increased the fat oxidation rate (SMD = 0.73; 95% CI = 0.19 to 1.27).
This increment was consistent with a significant (p = 0.04) reduction of the respiratory exchange ratio (SMD = -0.33; 95% CI = -0.65 to -0.01) and a significant (p = 0.049) increase in the oxygen uptake (SMD = 0.23; 95% CI = 0.01 to 0.44).
The results also showed that there was a dose-response effect of caffeine on the fat oxidation rate, indicating that more than 3.0 mg/kg is necessary to obtain a statistically significant effect of this stimulant on fat oxidation during exercise.

📚meta-analysisn=606

Tabrizi R et al. • Critical reviews in food science and nutrition (2019)

“Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.”

Key Findings:

Thirteen RCTs with 606 participants were included in the meta-analyses.
Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.
Further research warranted to confirm findings

📚meta-analysisn=122579

Karlinski Vizentin V et al. • Neonatology (2024)

“As compared with late caffeine administration, early caffeine is associated with a reduction in BPD, IVH, ROP, late-onset sepsis, and PDA in preterm neonates, albeit increased mortality.”

Key Findings:

A total of 122,579 patients from 11 studies were included, 2 were randomized controlled trials (RCTs), and 63.9% of the neonates received early caffeine administration.
The composite outcome of BPD or death was also lower in the early caffeine group (OR: 0.76; 95% CI: [0.66-0.88]; p < 0.0003).
Mortality rate was higher in the early caffeine group (OR: 1.20; 95% CI: 1.12-1.29; p < 0.001).

📚meta-analysisn=95

Gilsanz L et al. • Nutrients (2024)

“CAF+nitrates did not offer further benefits on exercise performance or physiological variables from the isolated intake of CAF and nitrates.”

Key Findings:

The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
CAF+nitrates did not affect heart rate during submaximal exercise trials over CAF alone (g = 0.04; 95% CI = -0.31 to 0.40; p = 0.80) or nitrates alone (g = -0.15; 95% CI = -0.50 to 0.20; p = 0.40).
Likewise, CAF+nitrates did not affect oxygen uptake during submaximal exercise trials over CAF alone (g = -0.04; 95% CI = -0.45 to 0.37; p = 0.84) or nitrates alone (g = -0.29; 95% CI = -0.70 to 0.12; p = 0.16).

📚meta-analysisn=254

Compare with Others Find Based on Your Goals

Wang Z et al. • Nutrients (2022)

“More evidence is needed to establish the ergogenic effect of caffeine on endurance running in women or the best dose to maximize the ergogenic benefits of caffeine supplementation.”

Key Findings:

A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD) estimated by Hedges’ g and 95% confidence intervals (CI).
The meta-analysis revealed that the time to exhaustion in running tests was improved with caffeine (g = 0.392; 95% CI = 0.214 to 0.571; p < 0.001, magnitude = medium).
Subgroup analysis revealed that caffeine was ergogenic for time to exhaustion trials in both recreational runners (g = 0.469; 95% CI = 0.185 to 0.754; p = 0.001, magnitude = medium) and trained runners (g = 0.344; 95% CI = 0.122 to 0.566; p = 0.002, magnitude = medium).
The meta-analysis also showed that the time to complete endurance running time trials was reduced with caffeine in comparison to placebo (g = −0.101; 95% CI = −0.190 to −0.012, p = 0.026, magnitude = small).

View all 40+ studies

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Caf9.5

Caffeine

compound

Caffeine (1,3,7-Trimethylxanthine)

Blocks adenosine receptors to boost alertness, reaction time, and endurance — one of the most proven ergogenic aids.

energyperformancecognitionstimulantfocuspre-workoutalertness

40+ studies

Evidence

Reviewed 19 days ago

moderate

Safety

100-200mg

Dose

1- days

Time to Effect

Pill/capsule for precise dosing

Best Form

Mechanisms of Action

🧠

Adenosine Blocking

Prevents the tiredness signal from reaching your brain

⚡

Catecholamine Release

Increases adrenaline and dopamine activity

🔥

Fat Oxidation

Enhances fat burning during exercise

Biological PathwayBeta

How Caffeine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.

Supplement

Molecular Target

Biological Process

Health Outcome

Strong

Moderate

Emerging

strong

moderate

emerging

Tap node to isolate • Pinch to zoom • Tap edge for research

Recommended Dose

100-200mg

50mg400mg

Optimal Timing

Morning
30-60 minutes before exercise

Can be taken without food

Available Forms

Form	Type
💊Pill/capsule for precise dosing	Recommended
💊Coffee (~95mg per 8oz)	Alternative
🍵Tea (~50mg per 8oz)	Alternative
💊Pre-workout supplements	Alternative

Pills allow precise dosing. Coffee and tea contain beneficial compounds but variable caffeine content.

Duration

Minimum: 1 days

Optimal: days

Cycling: Consider periodic breaks (1-2 weeks) to reset tolerance. Tolerance to stimulant effects develops within 1-2 weeks of daily use.

Note: Avoid within 6-8 hours of bedtime. Half-life is 5-6 hours. Effects are stronger on an empty stomach but may cause stomach upset.

👁️

Increased Alertness

Feel more awake and mentally sharp

📅 15-45 minutes

95% of users notice thispositive

🎯

Improved Focus

Better concentration on tasks

📅 30-60 minutes

85% of users notice thispositive

🏃

Better Exercise Performance

Especially for endurance activities

📅 30-60 minutes

80% of users notice thispositive

😰

Jitteriness

Anxiety or restlessness at higher doses

📅 30-60 minutes

30% of users notice thistrade-off

😴

Sleep Disruption

Can interfere with sleep if taken too late

📅 If consumed within 6 hours of bed

60% of users notice thistrade-off

ModerateMax safe dose: <200 mg/day in pregnancy; <300 mg/day in lactation

🟡

Pregnant/nursing

Limit to 200mg/day maximum

🔴

Children

Not recommended; limit to minimal amounts

🔴

Anxiety disorders

Use with caution or avoid; may worsen symptoms

Who Should NOT Take This

Severe anxiety disorders
Uncontrolled high blood pressure
Heart arrhythmias
Pregnancy (limit to 200mg/day)

Drug Interactions

Stimulant medications (Adderall, etc.)moderate

Additive stimulant effects; may increase heart rate and blood pressure

MAO inhibitorsmoderate

May increase caffeine effects and cardiovascular stress

Certain antibiotics (Cipro)mild

Can slow caffeine metabolism, intensifying effects

theophyllinesevere

Increased theophylline toxicity risk

ephedrinesevere

Dangerous cardiac stimulation, arrhythmias

Possible Side Effects

Jitteriness/anxiety

mildcommon

Tip: Lower dose or take with L-theanine

Insomnia

moderatecommon

Tip: Avoid afternoon/evening consumption

Increased heart rate

mildcommon

Tip: Lower dose

Withdrawal headache

moderatecommon

Tip: Taper gradually rather than stopping abruptly

Warnings

Highly addictive; withdrawal symptoms are common
Tolerance develops quickly with daily use
Can mask fatigue rather than address underlying causes
May worsen anxiety in susceptible individuals

✦ L-Theanine

L-theanine smooths out caffeine's edge

Alert focus without jitteriness; the 'smart caffeine' stack

⟡ Creatine

Different mechanisms for performance

Caffeine for endurance/alertness, creatine for power output

⊕ Alpha-GPC

stacks-well

Common nootropic stack for focus

Enhanced alertness and cognitive performance

⟡ BCAAs

Common pre-workout combination

BCAAs for muscle support, caffeine for energy and focus

✦ Green Tea Extract

Classic combination for fat oxidation

Enhanced thermogenic and cognitive effects

⟡ MCT Oil

Popular combination for energy and focus

Enhanced alertness and sustained energy

⟡ Sodium Bicarbonate

Different ergogenic mechanisms

Additive performance benefits

⟡ Theacrine

Enhanced and prolonged energy when combined

Faster onset (caffeine) with sustained energy (theacrine)

⟡ Tyrosine

Both support alertness through different mechanisms

Enhanced mental performance; start with lower doses of each

Top studies from 40+ peer-reviewed papers

📚meta-analysisn=2020

Collado-Mateo D et al. • Nutrients (2020)

“However, the fitness level of the participant may modulate the magnitude of the effect of caffeine on fat oxidation during exercise.”

Key Findings:

A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The meta-analysis revealed that caffeine significantly (p = 0.008) increased the fat oxidation rate (SMD = 0.73; 95% CI = 0.19 to 1.27).
This increment was consistent with a significant (p = 0.04) reduction of the respiratory exchange ratio (SMD = -0.33; 95% CI = -0.65 to -0.01) and a significant (p = 0.049) increase in the oxygen uptake (SMD = 0.23; 95% CI = 0.01 to 0.44).
The results also showed that there was a dose-response effect of caffeine on the fat oxidation rate, indicating that more than 3.0 mg/kg is necessary to obtain a statistically significant effect of this stimulant on fat oxidation during exercise.

📚meta-analysisn=606

Tabrizi R et al. • Critical reviews in food science and nutrition (2019)

“Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.”

Key Findings:

Thirteen RCTs with 606 participants were included in the meta-analyses.
Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.
Further research warranted to confirm findings

📚meta-analysisn=122579

Karlinski Vizentin V et al. • Neonatology (2024)

“As compared with late caffeine administration, early caffeine is associated with a reduction in BPD, IVH, ROP, late-onset sepsis, and PDA in preterm neonates, albeit increased mortality.”

Key Findings:

A total of 122,579 patients from 11 studies were included, 2 were randomized controlled trials (RCTs), and 63.9% of the neonates received early caffeine administration.
The composite outcome of BPD or death was also lower in the early caffeine group (OR: 0.76; 95% CI: [0.66-0.88]; p < 0.0003).
Mortality rate was higher in the early caffeine group (OR: 1.20; 95% CI: 1.12-1.29; p < 0.001).

📚meta-analysisn=95

Gilsanz L et al. • Nutrients (2024)

“CAF+nitrates did not offer further benefits on exercise performance or physiological variables from the isolated intake of CAF and nitrates.”

Key Findings:

The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
CAF+nitrates did not affect heart rate during submaximal exercise trials over CAF alone (g = 0.04; 95% CI = -0.31 to 0.40; p = 0.80) or nitrates alone (g = -0.15; 95% CI = -0.50 to 0.20; p = 0.40).
Likewise, CAF+nitrates did not affect oxygen uptake during submaximal exercise trials over CAF alone (g = -0.04; 95% CI = -0.45 to 0.37; p = 0.84) or nitrates alone (g = -0.29; 95% CI = -0.70 to 0.12; p = 0.16).

📚meta-analysisn=254

Compare with Others Find Based on Your Goals

Wang Z et al. • Nutrients (2022)

“More evidence is needed to establish the ergogenic effect of caffeine on endurance running in women or the best dose to maximize the ergogenic benefits of caffeine supplementation.”

Key Findings:

A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD) estimated by Hedges’ g and 95% confidence intervals (CI).
The meta-analysis revealed that the time to exhaustion in running tests was improved with caffeine (g = 0.392; 95% CI = 0.214 to 0.571; p < 0.001, magnitude = medium).
Subgroup analysis revealed that caffeine was ergogenic for time to exhaustion trials in both recreational runners (g = 0.469; 95% CI = 0.185 to 0.754; p = 0.001, magnitude = medium) and trained runners (g = 0.344; 95% CI = 0.122 to 0.566; p = 0.002, magnitude = medium).
The meta-analysis also showed that the time to complete endurance running time trials was reduced with caffeine in comparison to placebo (g = −0.101; 95% CI = −0.190 to −0.012, p = 0.026, magnitude = small).

View all 40+ studies

What would you like to do next?

Related Supplements

Cit8.5

Citicoline

Dual precursor to acetylcholine and phosphatidylcholine — enhances memory, focus, and brain cell membrane repair.

Phs8.5

Phosphatidylserine