The study and its comparison
Thirty-four healthy adults completed testing with an active drink and placebo. The formulation contained 200 milligrams of theanine plus alpha-GPC, phosphatidylserine and chamomile. [1]
Subjective stress response was lower at one hour and the cortisol response was lower at three hours. Cognitive performance did not improve. A brain-wave finding appeared in a higher-anxiety subgroup and did not correlate with the stress changes. [1]
What the finding establishes
Because the drink contained several ingredients, this trial does not isolate theanine or establish how long every preparation works. Neurobrands funded the study; the authors reported that the funder did not direct design, conduct or interpretation. The laboratory stress task is not a diagnosed anxiety disorder. [1]
A hypothetical distinction
Imagine a mixture changes a stress rating but not task accuracy. It supports neither an isolated-ingredient claim nor a general cognition claim.
| Detail | Interpretation |
|---|---|
| Measured outcome | Keep the endpoint specific |
| Study preparation | Not every retail product |
| Remaining uncertainty | Not resolved by a mechanism |
Sources for this article
- Anti-Stress, Behavioural and Magnetoencephalography Effects of an l-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial - PMC
Source consulted: 2026-09-19. This is a reference resource, not a claim that we conducted the studies or tested a product.