Brain & focus / caffeine and L-theanine
caffeine and L-theanine
Evidence for brain & focus, scored from the published research.
attention and focus
promising78/100 Evidence ScoreConfidence: high4 studies3 RCTs
Multiple human studies report a positive effect.
- 4 human studies (71 participants across the 2 with counts recorded; 2 review/meta-analysis not counted individually)
- Studies point in broadly the same direction
- Still unknown: few longer-duration studies
References (4)
- The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.randomized controlled trial (RCT) · Nutritional neuroscience · 2010
- l-theanine: From tea leaf to trending supplement - does the science match the hype for brain health and relaxation?systematic review · Nutrition research (New York, N.Y.) · 2025
- L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance.randomized controlled trial (RCT) · The Journal of nutrition · 2008
- Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task.randomized controlled trial (RCT) · Neuropharmacology · 2012
Evidence Scores are computed mechanically from the published research (PubMed / Semantic Scholar / OpenAlex): study design, participant numbers, and consistency across studies. An LLM is used only to extract study data, never to decide a score.
This is research-based information, not medical advice, and not a diagnosis. Consult a qualified professional about your own situation.