Caffeine + L-theanine
BGood evidenceThe combo improves attention-switching and reduces the jitter/anxiety of caffeine alone.
Grade B — Good evidence
What it does
Caffeine boosts alertness; L-theanine smooths it. Together they improve speed and accuracy on attention-demanding tasks better than caffeine alone.
How to take it
~50–100 mg caffeine + 100–200 mg L-theanine (roughly 1:2). Use for focused work blocks, not late in the day.
Caveats & safety
Tolerance builds; cycle it. Not a substitute for sleep. Skip if caffeine-sensitive.
The evidence
Owen GN, et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci.
2008 · RCT, double-blind crossover
Improved accuracy on attention-switching and reduced susceptibility to distraction.
Effect: Significant improvement in speed/accuracy vs placebo and vs caffeine alone.
Read on PubMed →Should this be in your routine?
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