Oxygen. While vital to human life support systems, oxygen is susceptible to conversion into active oxygen by environmental factors and life-style choices. Once active, oxygen begins to oxidize cells and tissues, creating wrinkles, blemishes, and can promote the onset of age related mental disorders such as dementia.
Active oxygen is also strongly linked with life-style related diseases, such as arteriosclerosis and diabetes. Cancer too can be promoted through oxidation, when active oxygen molecules damage DNA.

Humans are under constant threat of oxidation damage from active oxygen.
To protect against this threat, humans have developed some natural weapons, namely in the form of "SOD" (an enzyme that eliminates oxygen) and "scavengers" to fight against active oxygen. Scavengers are contained in foods, and tea catechins are among the strongest of them. Tea catechins protect us by eliminating active oxygen through the donation of their own electrons, and inactivating the oxygen molecules.

Rats were fed with usual feed (A) and feed containing tea catechins (B) for one week and the anti-oxidative level in the rat intestine was determined. Results showed that there was approximately twice the level of the internal anti-oxidative substance (Vitamin E) fed tea catechins.
Anti-aging as well as prevention of life-style related diseases may be promoted due to the prevention of oxidization.