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Promising but not conclusive evidence for selected attention and cognitive outcomes; combination effects with caffeine are modest and context-specific.
Recent randomized-trial meta-analyses suggest L-theanine may improve some reaction-time or attention outcomes, and theanine plus caffeine may produce small cognitive or mood benefits. Other cognitive measures are unchanged, and clinical significance remains uncertain.
Recent meta-analytic findings include acute testing after single doses, often around 200 mg for L-theanine alone. Combination studies vary in both theanine and caffeine amounts.
Short randomized trials generally report good tolerability, but the evidence base is much smaller than for established nutrients or caffeine and does not establish long-term safety across all populations.
V NRGY lists L-theanine and caffeine sources but does not publish their amounts. The site should not claim that the finished product reproduces the doses or effects studied in L-theanine/caffeine trials.
Cognitive and affective effects of L-Theanine: a systematic review and meta-analysis of 31 randomized trials (Systematic review and meta-analysis of randomized controlled trials; PMID 42410082)
Population/scope: 31 randomized trials; 1,168 healthy and clinical participants
Evidence scope: Attention, stress, anxiety, depressive symptoms, fatigue, and safety
Finding: A single 200 mg dose improved choice reaction time; acute stress effects were modest, fatigue was not improved, and anxiety findings were inconsistent.
Limitations: Some stress findings were influenced by high-risk-of-bias studies, clinical outcomes were inconsistent, and stronger confirmation is needed outside short-term attention effects.
Directness: Relevant human evidence · verified 2026-10-02
Important: Ingredient-level evidence is not proof that a finished product has the same effect. Dose, form, population, duration, and formulation must match.
For informational purposes only; not individualized medical advice.