Caffeine: Clinical Evidence & Substantiation Summary

Clinical Trials
450
Strongest Evidence
Focus & Physical Performance
Typical Dosage
50–200 mg per dose
Common Forms
Caffeine anhydrous

What Is Caffeine?

Caffeine is the most widely consumed psychoactive substance in the world. As a methylxanthine, it acts as a central nervous system stimulant, metabolic enhancer, and performance booster with a vast clinical evidence base.

Mechanism of action: Caffeine primarily works as an adenosine receptor antagonist. By blocking adenosine (which promotes sleepiness), it increases the firing of neurons and the release of neurotransmitters like dopamine and norepinephrine. It also promotes fatty acid oxidation and spares muscle glycogen during exercise.

Clinical Evidence Summary

Below are 3 key clinical studies on Caffeine. Nutra Comp analyses 450+ studies in its full clinical evidence report.

Systematic review and meta-analysis2019PMID: 30653643

Caffeine and exercise performance: meta-analysis

Population: Over 40 RCTs

Key finding: Caffeine (3–6 mg/kg) significantly improved endurance, muscular strength, and power output (p<0.001) across various athletic disciplines.

Caffeine and metabolic rate: clinical evaluation

Population: 12 healthy adults

Key finding: A single 200 mg dose of caffeine significantly increased resting metabolic rate by 7–11% and increased lipid oxidation (p=0.02).

RCT crossover2019PMID: 31142457

Low-dose caffeine and cognitive task performance

Population: 36 adults

Key finding: Low doses (40–60 mg) significantly improved reaction time, sustained attention, and vigilance compared to placebo (p<0.01).

Evidence-Based Structure–Function Claims

Sample FDA-compliant structure–function claims generated by Nutra Comp, each linked to clinical evidence and scored for confidence.

10
Supports mental alertness and focus
Category: Cognitive · Confidence: 10/10
10
Supports physical endurance and performance
Category: Performance · Confidence: 10/10
9
Supports healthy metabolic rate and fat oxidation
Category: Metabolism · Confidence: 9/10

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Related Ingredients

L-Theanine
28 studies · Relaxation & Focus
Creatine Monohydrate
186 studies · Muscle Strength & Power
L-Citrulline
29 studies · Exercise Performance

Key Terms

Randomised Controlled Trial (RCT)Dose-Response RelationshipClinically Effective Dose

Frequently Asked Questions

What is caffeine anhydrous?

Anhydrous means 'without water.' It is a highly concentrated, dehydrated powder form of caffeine that is absorbed faster than natural food sources of caffeine. It is the standard form used in sports nutrition.

How much caffeine is 'too much'?

The FDA suggests that for healthy adults, 400 mg a day is the amount not generally associated with negative effects. Sensitivity varies significantly between individuals.

Why combine caffeine with L-Theanine?

Clinical studies show that L-Theanine can 'smooth' the caffeine experience, reducing jitteriness and providing a more stable, focused mental state without the crash.

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