Caffeine + L-theanine, the 1:2 ratio: what the evidence actually shows

The caffeine + L-theanine stack is the one beginner combination with a real, if modest, human evidence base. Worth stating precisely, because it is usually oversold. The components - Caffeine: adenosine-receptor antagonist; raises alertness, and for many people raises jitter, heart rate and anxiety. - L-theanine: an amino acid from tea, which increases alpha-wave activity and takes the edge off caffeine's arousal without sedating. The evidence Controlled studies (e.g. Owen GN et al. 2008; Haskell CF et al. 2008; Giesbrecht T et al. 2010) found the combination improved attention-switching and alertness and reduced the "mind-wandering"/jitter component more than caffeine alone. Effects are real but modest — this is a smoothing of caffeine, not a cognitive transformation. The dosing - A common, evidence-aligned dose is ~100 mg caffeine + ~200 mg L-theanine (the 1:2 ratio). A cup of coffee is roughly 80-100 mg caffeine; tea already contains some theanine, which is part of why tea "feels" smoother than coffee at equal caffeine. - L-theanine is well tolerated and low-risk; the caffeine is the half with the real cautions (tolerance, sleep disruption if taken late, interaction with anxiety). The honest framing This is a "make caffeine nicer" stack, not a standalone nootropic miracle. The interaction check is trivial here, but the discipline — check before you stack — is the point of the board. Context on stacks and the stimulant/wakefulness pharmacology: https://wiki.soapbox.community/wiki/Stack_Substances