From: Andy Soos, ENN, Published August 23, 2010 02:13 PM
Drinking tea is supposed to be healthy for you because of what it contains. In this case let us consider polyphenols. In theory, a polyphenol has the ability to act as an antioxidant to scavenge free radicals and up-regulate certain metal chelation reactions. An antioxidant helps to regulate or clean up the cell's internal functions and so make you healthier as a result. The first measurements of healthful antioxidant levels in commercial bottled tea beverages has concluded that health-conscious consumers may not be getting what they pay for: healthful doses of those antioxidants, or "poylphenols," that may ward off a range of diseases.
Tea is the agricultural product of the leaves of the Camellia sinensis plant, prepared and cured by various methods. "Tea" also refers to the aromatic beverage prepared from the cured leaves by combination with hot or boiling water, and is the common name for the Camellia sinensis plant itself.
Tea contains various types of polyphenols, a type of antioxidant. In a freshly picked tea leaf, polyphenols can compose up to 30% of the dry weight. Polyphenols are highest in concentration in white and green teas, while black tea has substantially fewer.
The health benefits from drinking tea is sometimes pro and sometimes con. The theory is that the antioxidants do some good. Tea, after water, is the most commonly used world wide beverage.
Scientists have just reported at the 240th National Meeting of the American Chemical Society (ACS) that many of the increasingly popular beverages included in their study, beverages that account for $1 billion in annual sales in the United States alone, contain fewer polyphenols than a single cup of home brewed green or black tea. Some contain such small amounts that consumers would have to drink 20 bottles to get the polyphenols present in one cup of tea.
"Consumers understand very well the concept of the health benefits from drinking tea or consuming other tea products," said Shiming Li, Ph.D., who reported on the new study with Professor Chi-Tang Ho and his colleagues. "However, there is a huge gap between the perception that tea consumption is healthy and the actual amount of the healthful nutrients — polyphenols — found in bottled tea beverages. Our analysis of tea beverages found that the polyphenol content is extremely low."
Li and colleagues measured the level of polyphenols of six brands of tea purchased from supermarkets. Half of them contained what Li characterized as "virtually no" antioxidants. The rest had small amounts of polyphenols that Li said probably would carry little health benefit, especially when considering the high sugar intake from tea beverages.
The six teas Li analyzed contained 81, 43, 40, 13, 4, and 3 milligrams (mg.) of polyphenols per 16-ounce bottle. One average cup of home-brewed green or black tea, which costs only a few cents, contains 50-150 mg. of polyphenols.
A regular tea bag, for example, weighs about 2.2 grams and could contain 175 mg. of polyphenols, Li said. But polyphenols degrade and disappear as the tea bag is steeped in hot water. The polyphenol content also may vary as manufacturers change their processes, including the quantity and quality of tea used to prepare a batch and the tea brewing time.
If one drinks tea to be healthy, one is better off with fresh brewed tea and not the better tasting commercial varieties.
For further information: http://www.eurekalert.org/pub_releases/2010-08/acs-btb080610.php