Which catechins retarded oxidation most effectively depended on the specific environment, with no one antioxidant always leading or trailing the pack. To retard the rancidity that oxidation can trigger in salad oil, manufacturers currently add antioxidants. The Davis pair found that in bulk corn oil, EGC outperformed EGCG, ECG, and a couple other catechins. Sometimes, the catechins effectively lost their antioxidant property entirely and became, instead, a promoter of oxidation. Luckily, he adds, the situations where this is most likely to occur tends to be somewhat unusual.
Many metals are good at donating electrons, thus fostering oxidation.
Ordinarily, to keep such potentially dangerous electron transfers under control, antioxidants and other materials bind to free metals so that their electrons stay put. However, Frankel observes, under stress, such as when the body is fighting an infection, coping with inflammatory disease, or burdened with a metal overload, some of the metals may become freed. Most of the catechin studies have been performed in test tubes or isolated cells. That's a long way from modeling a human being, whose internal chemistry will be complex, Frankel points out. Mitscher was so compelled by his own new data that he now consumes a nutritional supplement of green-tea catechins.