Green Tea and Roasted Green Tea Affect Human Refreshment and Stress Recovery

A new study led by Chie Kurosaka, published in Scientific Reports, revealed that green tea, including its roasted form known as hojicha, might offer benefits related to mental task performance, refreshment, and stress recovery in humans.

The research included 20 young, healthy male participants who were asked to perform arithmetic tasks while consuming hot water, green tea, or hojicha. Physiological responses, including heart rate, blood pressure, and other indices, were recorded alongside participants' subjective assessments of fatigue and stress.

Results showed that both green tea and hojicha led to improvements in mental performance and feelings of refreshment and reduced fatigue. These positive effects occurred even with small amounts of tea and within short durations, consistent with everyday consumption habits.

Interestingly, roasted green tea or hojicha, which has less caffeine, catechins, and vitamins than green tea due to its roasting process, still improved task performance and seemed to prevent fatigue accumulation even with repeated task performance. This suggests that the relaxing aroma from roasted green tea could play a role in these benefits.

Green tea has long been celebrated for its health benefits, including its antioxidant properties and its potential for reducing disease risk. Components like catechins and L-theanine, found in green tea, have been associated with numerous health advantages, including thermogenic effects and improved cognitive functions.

The study leveraged various scientific instruments and metrics to gather comprehensive physiological and subjective data, ranging from heart rate variability to task performance. This allowed for an in-depth analysis of how tea components and their aromatic properties might influence human physiology and psychology in a short-term context.

The researchers note some limitations, such as the study’s focus on young male participants and the fixed order of beverage consumption that did not net out fatigue from task repetition. Nevertheless, the findings add to the growing body of evidence supporting the health benefits of tea and stress the importance of further exploring the effects of tea aromas.

For more details on this research, readers can access the full study available at Scientific Reports, with the DOI: https://doi.org/10.1038/s41598-024-59383-y

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