Aug. 23, 2010 -- Bottled tea may be all the rage among health-conscious people, but it may not have as many health benefits as you think.
Bottled tea is billed as being healthful because it contains polyphenols, antioxidants that may help ward off a range of diseases, including cancer.
But scientists say they’ve found that many of the popular bottled tea drinks contain fewer polyphenols than a single cup of home-brewed green or black tea.
And some contain such small amounts that a person would have to drink 20 bottles to get the same polyphenol benefit in a single cup of tea.
“Consumers understand very well the concept of the health benefits from drinking tea or consuming other tea products,” says Shiming Li, PhD, of the New Jersey-based life sciences company WellGen Inc. “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, an analytical and natural product chemist for WellGen, says in a news release that bottled commercial tea also contains other substances, including large amounts of sugar and the accompanying calories that people who are working on losing weight may be trying to avoid.
WellGen develops medical foods for patients with diseases, including a proprietary black tea product that he says will be marketed for its anti-inflammatory benefits, due in part to a high content of polyphenols.
Bottled Tea Polyphenol Levels
In the study, Li and colleagues measured polyphenol content of six brands of tea purchased in supermarkets.
The six teas he analyzed were found to have 3-81milligrams of polyphenols per 16-ounce bottle. On average, a cup of home-brewed green or black tea contains 50-150 milligrams of polyphenols.
“Someone would have to drink bottle after bottle of these teas in some cases to receive health benefits,” Li says. “I was surprised at the low polyphenol content. I didn’t expect it to be at such a low level.”
Tea is the world’s most widely drunk beverage. Sales of tea have quadrupled in the United States since 1990, constituting a $7 billion industry.
Polyphenols Good for Health
Polyphenols and other antioxidants in tea have been shown to reduce the risk of cancer, heart disease, and other maladies.
Li says some commercial teas list polyphenol amounts on their labels, but he says these claims may be incorrect because no industry or government standards exist for measuring and listing the healthful compounds in a product.
A regular tea bag, he says, could contain as much as 175 milligrams of polyphenols.
But the compounds degrade and disappear as the tea bag is soaked in hot water. “Polyphenols are bitter and astringent, but to target as many consumers as they can, manufacturers want to keep the bitterness and astringency at a minimum,” Li says. “The simplest way is to add less tea, which makes the tea polyphenol content low, but tastes smoother and sweeter,” he says.
The study is being presented during the 240th National Meeting of the American Chemical Society in Boston.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.