Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Caffeine (Anhydrous) | L-Theanine | |
|---|---|---|
| Category | Training Compounds | Amino Acids |
| Standard Dose | 100-400mg daily (1-3mg/kg bodyweight for cognitive; 3-6mg/kg for athletic performance) | 100-200mg daily (or as needed for acute anxiety/focus) |
| Timing | 30-60 min before exercise or cognitive demand. Avoid within 8-10 hours of bedtime (half-life: 5-6 hours, but CYP1A2 polymorphisms cause wide variation). Morning preferred. | Flexible: morning for calm focus (stack with caffeine), before stressful events, or evening for relaxation/sleep onset. Onset: 30-60 minutes oral, 15-20 min sublingual. |
| Cycle Duration | ongoing with periodic tolerance resets (1-2 weeks off every 8-12 weeks) | ongoing or as needed |
| Evidence Level | strong_human | strong_human |
Caffeine is a methylxanthine that primarily acts as a competitive adenosine A1 and A2A receptor antagonist. By blocking adenosine's inhibitory effects on neural activity, caffeine increases alertness, reduces perceived exertion, and delays fatigue. Downstream effects include: increased dopamine, norepinephrine, and acetylcholine release; enhanced calcium release from sarcoplasmic reticulum (direct muscle contraction enhancement); increased fat oxidation via enhanced lipolysis (HSL activation through cAMP/PKA pathway from PDE inhibition); and central drive enhancement (reduced RPE). Caffeine also inhibits phosphodiesterase (PDE), raising intracellular cAMP.
100-400mg daily (1-3mg/kg bodyweight for cognitive; 3-6mg/kg for athletic performance)
30-60 min before exercise or cognitive demand. Avoid within 8-10 hours of bedtime (half-life: 5-6 hours, but CYP1A2 polymorphisms cause wide variation). Morning preferred.
ongoing with periodic tolerance resets (1-2 weeks off every 8-12 weeks)
L-Theanine (gamma-glutamylethylamide) crosses the blood-brain barrier via the large neutral amino acid transporter. It increases alpha brain wave activity (8-13 Hz, associated with relaxed alertness), enhances GABA, serotonin, and dopamine levels in the brain, and antagonizes glutamate excitotoxicity by blocking glutamate binding at AMPA, kainate, and NMDA receptors. It also increases BDNF and NGF expression, supporting neuroplasticity. The combination of glutamate antagonism and GABA/serotonin enhancement produces anxiolysis without sedation — a 'calm focus' state.
100-200mg daily (or as needed for acute anxiety/focus)
Flexible: morning for calm focus (stack with caffeine), before stressful events, or evening for relaxation/sleep onset. Onset: 30-60 minutes oral, 15-20 min sublingual.
ongoing or as needed
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