Theanine, a major amino acid in green tea, exhibits a stress-reducing effect in mice and humans. Matcha, which is essentially theanine-rich powdered green tea, is abundant in caffeine. Caffeine has a strong antagonistic effect against theanine. The stress-reducing effect of matcha was examined with an animal experiment and a clinical trial. The stress-reducing effect of matcha marketed in Japan and abroad was assessed based on its composition. The stress-reducing effect of matcha in mice was evaluated as suppressed adrenal hypertrophy using territorially-based loaded stress. High contents of theanine and arginine in matcha exhibited a high stress-reducing effect. However, an effective stress-reducing outcome was only possible when the molar ratio of caffeine and epigallocatechin gallate (EGCG) to theanine and arginine was less than two. Participants (n = 39) consumed test-matcha, which was expected to have a stress-reducing effect, or placebo-matcha, where no effect was expected. Anxiety, a reaction to stress, was significantly lower in the test-matcha group than in the placebo group. To predict mental function of each matcha, both the quantity of theanine and the ratios of caffeine, EGCG, and arginine against theanine need to be verified.
The stress-reducing effect of matcha, a high-quality fine-powdered green tea, has recently been clarified by animal experiments and clinical trials. However, the effect of matcha added to confectioneries is not clear. One aim of this study was to evaluate the relationship between matcha components and their stress-reducing effect in mice that were loaded with territorially-based stress. Adrenal hypertrophy, a marker of stress, was significantly suppressed in stress-loaded mice that had ingested matcha components, displaying a caffeine and epigallocatechin gallate to theanine and arginine (CE/TA) ratio of 2 or less. Another aim was to evaluate, in humans, the stress-reducing effect of matcha in cookies using test-matcha (CE/TA = 1.79) or placebo-matcha (CE/TA = 10.64). Participants, who were fifth year pharmacy college students, consumed 4.5 g of matcha in three pieces of cookie daily for 15 days. Salivary α-amylase activity, a stress marker, was significantly lower in the test-matcha group than in the placebo group. These results indicate that the CE/TA ratio of tea components is a key indicator for the suppression of stress. Moreover, matcha with a CE/TA ratio of 2 or less displays a stress-reducing effect, even if it is included in confectionery products. Such products may also benefit individuals who have no habit of drinking matcha as a beverage.
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