Tea is one of the oldest herbal remedies in existence, dating back more than 4700 years, when infusions of the plant Camellia Sinensis were first brewed in China. Although modern medicine has diminished tea’s credibility as a cure-all solution, the benefits of tea still remain relevant today.
It's important to understand exactly what qualifies a beverage as "tea." When scientists use the word tea, they’re typically referring to organic black tea, green tea, white tea, oolong tea or pu-erh tea. The common link between these five categories is that they are each made from the leaves of the Camellia Sinensis plant. Herbal "teas" aren't actually scientifically considered teas at all, though they may be commonly referred to as such. These kinds of teas include those like chamomile and peppermint, which are made using a variety of different plants with varying nutritional values.
What makes these five types of teas distinct from one another? The preparation and maturity of tea leaves determine both the flavor and the nutritional content of each beverage. The leaves used to make black tea are both wilted and fully oxidized, meaning that they are dried and modified through prolonged exposure to air. Green tea goes though the wilting process, but not oxidization, while oolong tea leaves are wilted and oxidized, but not to the prolonged extent of black tea leaves. White tea is the young tea bud, and is neither wilted nor oxidized. Finally, Pu-erh tea leaves are fermented.
Flavonoids, naturally occurring molecules frequently investigated for their antioxidant properties, are one type of potentially beneficial compound found in tea. Recognizing the scientific community's interest in the types and levels of flavonoids in foods, the Nutrient Data Laboratory in the Agricultural Research Service of the U.S. Department of Agriculture has been measuring the flavonoid content of a wide variety of foods since at least 2003. (Source: USDA Database for the Flavanoid Content of Selected Foods, Release 2.1, January 2007). According to USDA's measurements, brewed Green Tea tends to contain more Flavan-3-ols (a type of flavonoid found in tea) than brewed Black Tea. This may be why Green Tea is believed by some people to be more "healthy" than Black Tea.