Antioxidant Properties Of Polyphenols Research Articles

Polyphenols: antioxidants and beyond

Research on the effects of dietary polyphenols on human health has developed considerably in the past 10 y. It strongly supports a role for polyphenols in the prevention of degenerative diseases, particularly cardiovascular diseases and cancers. The antioxidant properties of polyphenols have been widely studied, but it has become clear that the mechanisms of action of polyphenols go beyond the modulation of oxidative stress. This supplemental issue of The American Journal of Clinical Nutrition, published on the occasion of the 1st International Conference on Polyphenols and Health, offers an overview of the experimental, clinical, and epidemiologic evidence of the effects of polyphenols on health.

Anti-Stress Effect of Oolong Tea in Women Loaded with Vigil

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.