Green Tea Antioxidants and EGCg

What is green tea antioxidants and catechins?

Green tea antioxidants are called catechins.  Tea generally contains 11-17% of catechins and they are water soluble.  EGCg or epi-galo-catechin-galate is one of catechins.
Here is each of the green tea catechins % found in green tea.

EG  (0.9%)
EGC  (3.6%)
ECg  (2.2%)
EGCg (7.9%)

*Percentage of each catechin vary depending on cultivation, harvest seasons, harvested leaf type, processing style, and even brewing temperature.  This is an average %.  

Why is green tea antioxidants, especially EGCg, effective in keeping us healthy?

Green tea antioxidants are highly effective antioxidants compared to antioxidants found in other foods.  The table shows that the effectiveness of green tea antioxidants, especially EGCg, is significantly higher than others.  EGCg is 87.5 times more effective than vitamin C and 15 times more effective than BHT (wikipedia link) and BHA (wikipedia link) (These are chemical food additives to keep foods fresh).

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 26.3 12.9
ECg 116.3 57.0
EGC 117.6 57.6
EGCg 178.6 87.5
*half maximal inhibitory concentration (IC50) 
what's IC50? (link wikipedia)
Yoshino et. al. ; Biol Pharm. Bull 17, 146 (1994)

How do green tea antioxidants protect the body from free radicals?

Free radicals are created by various environmental toxins, radiation, foods, tobacco smoke, etc and we are continuously exposed to them.  Once free radicals enter the body, they attack lipids (fat), protein, enzymes, and DNA, which could lead to various ailments and cancer.
Green tea antioxidants suppress these free radical damages by deactivating these free radicals.

Read more; Battle between Antioxidants and Free Radicals



This is a summary from the Japanese Tea Instructor book.

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