Green tea / EGCG → Cognitive performance
Higher Green tea / EGCG moves Cognitive performance only in some conditions. Read the mechanism.
Wightman 2012 found that 135 or 270 mg of epigallocatechin gallate did not change computerised cognitive tasks or mood versus placebo in 27 healthy adults, though frontal blood flow fell at the lower dose. Dietz 2019 saw a small attention and psychomotor-speed rise after a matcha drink in 23 people.
Randomized trial · Contested · N=27
Supported by an experiment or a tightly identified design. Read the caveats.
Mechanism
Authors treat EGCG as the green-tea catechin that might change blood flow or attention. They do not isolate caffeine from the tea matrix. Wightman, Haskell, Forster, Veasey and Kennedy crossed 27 healthy adults through placebo, 135 mg, and 270 mg of EGCG. After 45 minutes they ran frontal-cortex tasks for 42 minutes. 135 mg lowered oxygenated and total haemoglobin in frontal cortex versus placebo. No cognitive or mood measure moved. Dietz, Dekker and Piqueras-Fiszman crossed 23 people through matcha tea, a matcha bar (4 g powder each), and matched placebos. Basic attention and psychomotor speed improved versus placebo. Other memory tasks barely moved. Mood did not. The drink beat the bar. Single-blind.
Caveats
Researchers assigned people to EGCG or matcha, so this is a trial stamp. An isolated catechin and a caffeinated powder are not the same drink. More papers of the same design do not settle the claim. Wightman is the clean EGCG file and is null on tasks. Dietz is 23 people and single-blind; matcha also carries caffeine and theanine. This is a journal entry, not medical advice and not a reason to drink green tea for memory.
Effect
qualitative. Wightman 2012: EGCG 135/270 mg, N=27, cognition and mood ns; CBF down at 135 mg. Dietz 2019: matcha vs placebo, N=23, attention/psychomotor speed up. Isolate vs tea matrix.
Nodes
Named confounders
Cite this page
What Causes What. “Green tea / EGCG → Cognitive performance.” https://whatcauseswhat.org/edges/e-green-tea-cognition (atlas updated 2026-09-02).
Papers
- Epigallocatechin gallate, cerebral blood flow parameters, cognitive performance and mood in healthy humans: a double-blind, placebo-controlled, crossover investigation.
EL Wightman, CF Haskell, JS Forster, RC Veasey, DO Kennedy · 2012 · Human psychopharmacology
- An intervention study on the effect of matcha tea, in drink and snack bar formats, on mood and cognitive performance.
C Dietz, M Dekker, B Piqueras-Fiszman · 2019 · Food research international (Ottawa, Ont.)