Matcha, caffeine and thinking under mild stress
What it found
In middle-aged and older adults, daily matcha for 12 weeks increased the amount of simple calculation work done under mild stress, while a single dose of caffeine sped up reaction times.
Matcha and caffeine affected thinking tasks differently.
What they found
Studies in people
Simple calculation work
After 12 weeks of daily matcha, people completed more simple addition work under time pressure than those taking placebo. The caffeine group only did more work after a single dose, not after 12 weeks.
Reaction times
A single dose of caffeine sped up reaction times on several attention and working memory tasks compared with placebo. Matcha also sped up reaction time on one attention task after a single dose, but this was likely due to its caffeine content.
Memory and motor skills
Neither matcha nor caffeine changed scores on memory tasks, facial expression recognition, visual information processing, or finger tapping speed.
Blood markers
After 12 weeks, there were no significant differences between groups in blood levels of proteins linked to Alzheimer's disease or in a marker of brain cell growth.
Mental state scores
After 12 weeks, the caffeine and matcha groups scored higher on a standard mental state exam than the placebo group. The placebo group's scores dropped over the 12 weeks.
What the authors conclude
“Ingesting matcha with caffeine improves both attention and work performance when suffering from psychological stress compared with caffeine alone.”
Also in their conclusions
- They conclude that matcha and caffeine had different effects on thinking tasks.
- They say that matcha intake increased simple workload and improved executive function, while caffeine accelerated reactions to work.
- They suggest that theanine, catechin, and caffeine together exert different effects than when they are present alone, and call for future studies on how these components affect brain activity.
How it was done
The authors wanted to find out whether the caffeine naturally present in matcha explains its effects on thinking, or whether the whole matcha drink does something more. They also wanted to see how matcha affects thinking in middle-aged and older adults who are under mild mental stress.
They recruited 51 healthy Japanese men and women aged 50 to 69 who reported a self-assessed decline in thinking skills. Participants were split into three groups and took either matcha, caffeine, or placebo capsules daily for 12 weeks. Thinking and calculation tasks were tested after a single dose and again after 12 weeks.
What it can’t tell you
- This study was in healthy Japanese adults aged 50 to 69 who already drank green tea, so the results may not apply to other groups.
- The stress in this study came from a 30-minute calculation task, so it may not reflect other kinds of stress in daily life.
- The study did not measure how stressed participants felt or check stress-related biomarkers, so it cannot show how matcha affects the experience of stress itself.
Who paid
- Conflicts
- Yoshitake Baba, Shun Inagaki, Sae Nakagawa, Makoto Kobayashi, and Takanobu Takihara are employees of ITO EN, LTD. HUMA R&D CORP. conducted participant recruitment, selection, allocation, observation, and data collection. Toshiyuki Kaneko was the doctor for this study and was contracted by HUMA R&D CORP. The study was properly implemented by a third party.
- Authors work at
- Central Research Institute, Japan
The paper
- Title
- Effects of Daily Matcha and Caffeine Intake on Mild Acute Psychological Stress-Related Cognitive Function in Middle-Aged and Older Adults: A Randomized Placebo-Controlled Study
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Baba Y, Inagaki S, Nakagawa S, Kobayashi M, Kaneko T, Takihara T (2021). Effects of Daily Matcha and Caffeine Intake on Mild Acute Psychological Stress-Related Cognitive Function in Middle-Aged and Older Adults: A Randomized Placebo-Controlled Study. Nutrients. doi:10.3390/nu13051700Free full textPubMed 34067795DOI
Summary written 29 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error