Antioxidants in Green Tea

Green tea consumption of as much as 20 cups per day has not been associated with any significant side effects. Many studies show that drinking 10 cups or more of green tea a day is associated with less incidence of various types of cancer and chronic diseases.

Acute studies reported the oral LD50 of EGCg was 2170mg/kg bw in mice.

Table 1. Antioxidants comparison

Antioxidants 1/IC50(mM)* Ratio
Vitamin C 2.0 1.0
Vitamin E 7.7 3.8
BHT – Food Additive 10.3 5.2
BHA – Food Additive 11.2 5.6
EC (Epicatechin) 26.3 12.9
TF (Theaflavin) 114.9 56.3
ECg (Epicatechin galate) 116.3 57.0
EGC (Epigalocatechin) 117.6 57.6
TFg-A (Theaflavin galate-A) 175.4 86.0
EGCg (Epigalocatechin galate) 178.6 87.5

*IC50, the half maximal inhibitory concentration, represents the concentration of an inhibitor that is required for 50% inhibition of its target. Yoshino, et al. Antioxidative effects of black tea theaflavins and thearubigens on lipid peroxidation of rat liver homogenates induced by tert-butyl hydroperoxide. Biol. Pharm. Bull. 17, 146 (1994)

What the table shows is that comparison of green tea antioxidants with other known substances such as vitamin C and BHT. Antioxidants in tea are described in ratio compared to Vitamin C. This means how effective antioxidants in tea are compared to vitamin C.