Performance
Caffeine (Camellia sinensis leaf)
Also known as: green tea extract, EGCG-containing caffeine, theine
Caffeine from Camellia sinensis (green tea) is a central nervous system stimulant that enhances alertness, focus, and endurance. This source also provides catechin antioxidants including EGCG.
Primary uses
- energy and alertness
- mental focus
- physical performance
- endurance
How it works
- adenosine receptor antagonism
- increases dopamine and norepinephrine
- enhances sympathetic nervous system activity
Dosage
- Typical range
- 50–200 mg caffeine daily for cognitive effects; up to 400 mg daily is generally safe for most adults
- Timing
- morning or early afternoon to avoid sleep disruption
- With food
- either, though food may delay absorption
- Duration
- tolerance develops; cycling recommended to maintain efficacy; effects typically last 3–5 hours
- Special populations
- pregnant women limit to <200 mg/day; sensitive individuals or anxiety disorders use lower doses or avoid
Forms
- green tea leaf extract· 70/100
- dried leaf powder· 70/100
Safety
Common side effects
- jitteriness
- anxiety
- insomnia
- elevated heart rate at high doses
Contraindications
- uncontrolled hypertension
- cardiac arrhythmias
- severe anxiety disorders
- pregnancy (limit to <200 mg/day)
Evidence notes
Extensive RCT evidence confirms caffeine's efficacy for cognitive performance, alertness, and endurance across numerous studies. Green tea source provides additional polyphenol benefits.
Grade A: Multiple well-designed human trials support the main claims.
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