Researchers from Japan recently established that green tea inhibits salivary chromogranin A (CgA), a biochemical marker of stress.
Eighteen people participated in three seven-day trials, consuming warm water (control) the first week, ordinary green tea (Sagara) the next week and another type of green tea called “shaded white tea” the third week. Researchers collected saliva to test CgA levels before consumption of each beverage, and again after the participants performed mental stress load tasks.
As predicted, CgA increased after mental tasks, but Sagara tea inhibited its release. Shaded white tea had an even greater anti-stress effect than Sagara, while also lowering scores on Total Mood Disturbance (which assesses tension/anxiety, depression, anger/hostility, fatigue, vigor and confusion) and improving performance on an arithmetic task.
Yoto A, et al. J Physiol Anthropol. 2014 Jul 17;33(1):20.