Effect of Sunrouge on the postprandial blood glucose level - A randomized, double-blind, crossover-study

Objective: Sunrouge tea is a special green tea with high content of epigallocatechin gallate (EGCG) which is reported having an inhibition effect of alfa-glucosidase activity and alfa-amylase activity. The aim of this study is to evaluate the suppressive effect of Sunrouge tea powder on postprandial blood glucose level. Methods: We conducted a randomized, placebo-controlled, double-blind, crossover study for twenty healthy volunteers (8 males and 12 females, aged from 20 to 60 years). Subjects consumed either Sunrouge tea powder beverage containing 140.2 mg of EGCG as test food, or the beverage containing corn flour instead of EGCG as placebo, together with loading meal (130 g of cooked rice). Blood glucose and insulin level of subjects were measured prior to and, 15, 30, 45, 60, 90 and 120 min after consumption of the loading meal. Result: Consumption of the test food showed significant suppress in the elevation of postprandial blood glucose level, but not in the insulin level, compared to that in the placebo group. The concentration of blood glucose at 15, 30 and 45 min after consumption of the test food were significantly lower than that of placebo (P=0.049, P=0.001 and P=0.003). Also, the changing values of blood glucose from 0 min of test food group were significantly lower than that of placebo group at 15, 30, 45 min after loading (P=0.004, P=0.0001 and P=0.003). The area under the curve of the changing values of blood glucose from 0 min of test food group was smaller than that of placebo group (P=0.085). Conclusion: These results indicate that Sunrouge tea powder which contains EGCG suppress the elevation of postprandial blood glucose level in human.