Green Tea Increases Glutathione and Plasma Antioxidant Capacity in Adults with the Metabolic Syndrome
In a randomized study involving 35 obese subjects with the metabolic syndrome, supplementation with 4 cups of green tea per day or 2 capsules of green tea extract plus 4 cups of water per day was found to be associated with significantly increased plasma antioxidant capacity (1.5 to 2.3 micromol/L and 1.2 to 2.5 micromol/L, respectively) and significantly increased whole blood glutathione (1783 to 2395 microg/g hemoglobin and 1905 to 2751 microg/g hemogloblin, respectively), as compared to controls, at 8 weeks. No significant effects on serum levels of carotenoids and tocopherols and glutathione peroxidase and catalase activities were found. The authors conclude, "Green tea extract significantly reduced plasma iron vs baseline (128 to 92 mcg/dL, P < .02), whereas copper, zinc, and selenium were not affected. These results support the hypothesis that green tea may provide antioxidant protection in the metabolic syndrome.