Tea is a beverage commonly consumed worldwide. Matcha is a type of green tea produced by drying and grinding tea leaves (Camellia sinensis L.) into a fine powder. Matcha contains catechin, theanine, and caffeine, which affect cognitive function. Epidemiological studies conducted in Japan have shown that green tea consumption improves cognitive impairment.
Previously, we found that daily matcha intake improves attention and executive function in middle-aged and older people. However, its effect on cognitive function in younger adults remains unclear. Moreover, it is unclear which cognitive functions are impaired by stress.
This study aimed to clarify whether the administration of matcha improves the attentional function of young adults after mild acute stress and which cognitive function is improved. We included 42 participants aged 25 to 34 years who consumed 2 g of matcha daily for 2 weeks. The Uchida-Kraepelin test was used to induce mild acute psychological stress. Memory, attention, facial expression recognition, working memory, visual information, and motor function were evaluated…Total catechins, theanine, and caffeine content in the daily intake of matcha (2070 mg) were 171.0 mg, 50.3 mg, and 72.5 mg, respectively.
Reaction times on the Stroop test for attentional function were statistically-significantly lower in the matcha group than in the placebo group. Correct hits in the emotion perception test increased statistically-significantly for participants in the matcha group compared to those in the placebo group. We found no statistically-significant between-group differences in the other tests.
In conclusion, after 2 weeks of matcha intake, the attentional function was maintained after mild acute psychological stress. Thus, matcha might improve cognitive function during or after stress conditions in young adults.
[Keywords: green tea, cognitive function, attention, young adult, randomized controlled trial, psychological stress]