A single dose of tea with or without milk increased plasma antioxidant activity in humans

European Journal of Clinical Nutrition, 2000; 54: 67-92

Leenen et al.

Purpose of Study

• To investigate the effect of black and green tea consumption, with and without milk, on plasma antioxidant activity.

Methods: study participants

• N=21• Non-smokers• Stable body weight• No medication• No dietary

supplements containing vitamin C, E, carotenoids, calcium or iron

Methods: experimental design

• RCT

• Treatments included the following– 300 ml black tea– 300 ml green tea– 240 ml black tea + 60 ml milk– 240 ml green tea + 60 ml milk

Methods: Analytical Procedure

• Plasma antioxidant activity was measured using FRAP, blood samples were taken at 30, 60, 90, 120 minutes.

• Total catechins in plasma were analyzed using HPLC.

Statistical Analysis

• Effects of tea and addition of milk to tea were evaluated by ANOVA; two sided P values were statisticaly significant at

P <0.05.

Results of the Study

• Consumption of black tea resulted in an increase in plasma FRAP activity.

• Consumption of green tea resulted in an even higher plasma FRAP activity than black tea.

• Addition of milk to either black or green tea did not significantly alter FRAP activity.

• Consumption of black or green tea resutled in an increase of catechins in plasma, but were higher in green tea.

Conclusion

• Consumption of a single dose of black or green tea induces a significant rise in plasma antioxidant activity in vivo with higher response attributed to green tea.