Cognition/Performance/Weight

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.

score

evidence

Caution

risk

Proven Benefits

01Reduces fatigue and sleepiness

02Boosts exercise performance

03Improves reaction time, attention

04May increase metabolic rate

05May improve memory recall

06May reduce Parkinson's risk

07May support weight management

Chemical Forms

Recommended

Caffeine anhydrous
Natural caffeine (coffee/tea/guarana)

Avoid

Highly concentrated liquid caffeine (risk of overdose/precise dosing difficult)

Expert Note

Caffeine anhydrous is the standard form in supplements and has well-characterized pharmacokinetics. Coffee and tea provide slower absorption due to fiber/polyphenols. Avoid bulk pure caffeine powders or highly concentrated liquids due to serious overdose risk; standard capsules or beverages allow safer dosing.

Protocol

Amount

100-200 mg

Frequency

Once daily, or pre-workout only

When

Morning or early afternoon; avoid within 8 hours of bedtime to prevent sleep disruption. Take with or without food.

Condition-Based Dosing

Caffeine-naive users or those sensitive to stimulants

50-100 mg to assess tolerance— Start low to assess anxiety, jitters, and heart rate response.

Endurance exercise performance

3-6 mg/kg bodyweight 30-60 minutes pre-exercise— Doses above 6 mg/kg increase side effects without proportional benefit.

Habitual heavy consumers (>400 mg/day)

Consider tapering or cycling to restore sensitivity— Chronic high intake leads to tolerance and dependency.

Safety & Limits

Upper Safe Limit

400 mg/day (FDA guidance for healthy adults); 200 mg/day during pregnancy

Cycling

Consider 1-2 caffeine-free days weekly, or a 2-week reset after prolonged daily use to reduce tolerance and dependency.

Contraindications

Pregnancy — limit to 200 mg/day or less; high intakes associated with adverse outcomes

Anxiety disorders or panic disorder — can trigger or worsen symptoms

Insomnia or sleep disorders — disrupts sleep architecture even if it doesn't prevent falling asleep

Arrhythmias or uncontrolled hypertension — acutely increases heart rate and blood pressure

GERD or peptic ulcer disease — increases gastric acid secretion

Bipolar disorder — can trigger mania or worsen sleep in vulnerable individuals

Synergies

L-theanine

L-theanine smooths caffeine's stimulating edge, reducing jitters and blood pressure spikes while preserving alertness.

Avoid Combining With

✕Adenosine and sleep pressure (caffeine blocks adenosine receptors; avoid when sleep is needed)
✕Alcohol (do not mix — masks sedation and impairs judgment)
✕Calcium supplements (wait 2+ hours — caffeine may slightly increase calcium excretion)
✕Iron supplements (wait 1-2 hours — tannins in tea/coffee inhibit iron absorption; caffeine itself may have minor effect)

Updated Invalid Date