New Study Links Daily Matcha Consumption to 23% Reduction in Cortisol Levels
A peer-reviewed study from Kyoto University followed 1,200 participants over 18 months — findings go well beyond what caffeine alone can explain.
A peer-reviewed study published in the Journal of Nutritional Biochemistry has provided the most robust evidence to date for matcha's stress-modulating effects — and the mechanism is more nuanced than the widely cited caffeine-L-theanine synergy.
What the study found
The Kyoto University research team recruited 1,200 participants across four cohorts: daily ceremonial-grade matcha drinkers, daily culinary-grade drinkers, L-theanine supplement users, and a control group.
"The whole-food matrix of high-grade tencha appears to produce effects that isolated supplementation cannot replicate."
What this means in practice
Grade matters. The study's data suggests that the difference between ceremonial and culinary grade represents a meaningfully different biochemical profile, not just a question of flavour.