After water, tea is the most widely consumed beverage in the world. There are 3 types: red tea (partially oxidized), black tea (fully oxidized), and green tea (non-oxidized; purest form)

Many claim that green tea plays a role in cancer prevention via decreased tumor growth and inhibition of metastases. Green tea may also decrease risk of heart disease via oxidation modifications of LDL’s.

The primary phenols in black tea are quercetin, theaflavin gallate, and theaflavin. The primary phenols found abundantly in green tea are flavanols which break down to quercetin (also found in apples and onions) and catechin (also found in licorice root). These two phenols are found to have therapeutic and possibly preventive effects.

Two publications were reviewed:

1. Jankin, Selman, Swierz. Why drinking green tea could prevent cancer. Nature. 1997. Looked at computer modeling of the effects of green tea in urokinase leading to cancer remission.
2. Ishikawa. Effects of green tea flavanoid supplementation on LDL oxidative modifications. AJCN. 1997. Found that lipid composition did not change between green tea and water groups, LDL lag time was significantly prolonged after tea consumption and no significant change in LDL lag time in water group.

Considerations for future studies include more in vitro clinically controlled human studies, distinguish between the effects of green tea from black tea (i.e. whole tea vs. flavanol extract, and studying types of teas (i.e. name brand, harvest/ fermentation process, caffeinated / decaffeinated, hot/bottled/iced) to determine the mechanism of action.