2003 年 49 巻 6 号 p. 436-443
The preventive effect of oolong tea on vigil stress was investigated in 55 Chinese women. The subjects received 4 servings of tea bag daily, the tea bags in each containing 2 g dry weight of oolong tea or barley tea, or else water, for a period of one week. The results of a questionnaire indicated that ingestion of oolong tea improved symptoms of stress such as stiffness of the shoulders, fatigue of the eyes and headaches, as well as ameliorated the stress-induced increase in the number of errors in calculation tasks compared with controls. In addition, plasma cortisol levels were significantly lower in the oolong tea group (17.84 ± 2.46 μg/dl) than in the barley tea group (21.33 ± 6.47 μg /dl) or water group (22.95 ± 6.98 μg/dl). Ingestion of oolong tea significantly alleviated the vigil stress-induced increase in plasma lipid peroxide levels, which may have been related to the stress-relieving effects of caffeine or antioxidant properties of polyphenols contained in the tea. These findings suggested that oolong tea has anti-stress effect, with no adverse effects on appetite or physical fitness.