Catechins are one type of polyphenol. They are classified as polyphenols since they contain more than one phenol ring in its chemical structure.
Catechins are the most medicinally important chemicals in green tea.
Green tea polyphenols are thought to prevent cancer, atherosclerosis, delay the appearance of wrinkles and aging, promote weight loss and even prevent infection by the AIDS virus.
There are of are four types of catechins in green tea. This accounts for one third by weight of the tea.
Green tea polyphenols (catechins) help prevent cancers of the gastrointestinal tract and prostate. These phytonutrients are potent inhibitors of the enzyme tyrosine kinase, the enzyme that phosphorylates proteins, which is essential for cell mitosis and growth. This interference by is believed to be the mechanism by which green tea prevents cancers of the gastrointestinal tract. Green tea polyphenols are also able to cross the blood-brain barrier where they can neutralize the free radicals generated in the brain.
Preventing free radical damage delays senile dementia and other chronic brain diseases. Green tea polyphenols may also prevent AIDS by its ability to bind to membrane receptors. They may also prevent cancer by inhibiting certain enzymes and preventing the formation of nitrosamines.
Catechins cross the blood-brain barrier and stimulates fat oxidation. Green tea catechins, specifically the EGCG (epigallocatechin gallate) model are believed to raise core body temperature. This thermogenic effect is similar to the one that caffeine produces, only of a longer duration.
Increased core temperature helps lower body weight. EGCG are now being used in natural weight loss formulas. EGCG is purported to reduce food intake, lower body weight and decrease blood cholesterol and triglyceride levels and is thought to interact with the leptin-appetite pathway to repress appetite