Caffeine
Natural stimulant found in coffee and tea that increases alertness, reduces fatigue, and enhances exercise performance in healthy adults.
Caffeine
Natural stimulant found in coffee and tea that increases alertness, reduces fatigue, and enhances exercise performance in healthy adults.
One of the most reliable cognitive and performance enhancers, but tolerance develops and afternoon use can disrupt sleep.
Caffeine is a methylxanthine stimulant naturally present in coffee beans, tea leaves, cacao, and guarana. It works primarily by blocking adenosine receptors in the brain, reducing perceived fatigue and increasing alertness. Large bodies of randomized trials confirm it acutely improves attention, reaction time, and endurance exercise capacity. It also has a well-documented thermic effect and is the most widely consumed psychoactive substance. Those who benefit most include people with occasional fatigue, shift workers, and individuals seeking acute exercise or cognitive enhancement. Those with
Proven Benefits
Protocol
Onset Time
Who Should Consider
Food Sources
- Brewed coffee (~80-100 mg per 8 oz cup)
- Black tea (~40-50 mg per 8 oz cup)
- Green tea (~25-35 mg per 8 oz cup)
- Dark chocolate (~20 mg per 1 oz serving)
- Guarana seeds (~double the caffeine by weight than coffee beans)
How It Works
Caffeine competitively antagonizes adenosine A1 and A2A receptors in the central nervous system, preventing the fatigue-promoting and sedative effects of adenosine. This increases neuronal firing and releases dopamine and norepinephrine, improving alertness and reaction time. In muscle tissue, caffeine may enhance calcium handling and blunt pain signaling, contributing to improved endurance and po