Catechins are found in green and white teas. The fermentation process used in black teas destroys much of the available catechin. These flavonoids are also found in some chocolates, cocoa, wine, fruits and vegetables.
The amount of catechin in tea leaves depends on various factors, including the type of tea, farm location, season and altitude. In general, catechins make up a quarter of the dry weight of a tea leaf. As the seasons progress, the concentration of catechins in the tea leaves increases, so summer tea crops contain more catechin than spring crops. Furthermore, young leave contain more catechin than older leaves. Tanins lend a bitter taste to the tea, so leaves harvested during the summer taste more astringent than those from the earlier spring crops.
Unlike black tea, green tea comes from unfermented tea leaves. This causes less damage or oxidation of the catechins and leaves more of the flavonoids available for absorption by the human body. As an antioxidant, catechin is 10 times more effective than beta-carotene or vitamin C. Green tea polyphenols have been shown more powerful and effective than those found in rosemary, vitamin E and vitamin C.
There are numerous benefits to the consumption of green tea. In lab studies, green tea catechins slowed the growth of cancer cells, protected cells from the damage of free radicals and reduced overall tumor growth. Green tea catechins seem to be so effective because they bind easily to proteins. They can block and prevent bacteria from destroying cells. Green tea flavonoids attach to viruses and prevent their “hooks” from grabbing cells.
Green tea catechins have been shown effective against dysentery and cholera. They minimize mouth bacteria that lead to tooth and gum damage. They fight Piccoli, the bacteria responsible for gastric ulcers. On the other hand, catechins encourage the growth of bifid bacteria, one of the good bacteria found in the intestines, and reduce the amount of bad bacteria.
Flavonoids such as catechin are important for cardiovascular health. By blocking the absorption of cholesterol, catechins decrease the overall level of cholesterol in the blood and lower the risk of atherosclerosis, the hardening and thickening of the artery walls. Catechins help prevent heart attacks, stroke, high blood pressure and blood clots.
Green tea catechins might help slow the aging process by flushing free radicals from the body. They have shown some promise in the field of diabetes prevention by obstructing digestive enzymes that absorb sugar. Catechins also detoxify the body by helping to remove harmful poisons such as mercury, lead, cadmium and chrome.