Compared with home-brewed green or black tea, bottled teas contained much lower doses of polyphenols … the antioxidant and nutrigenomic (gene-influencing) compounds believed responsible for the health benefits associated with tea.
Tea beverage sales in the U.S. total about $1 billion per year, but much of the money may be misspent, since a typical 16 oz. bottle contains fewer polyphenols than just one 5 oz. cup of home-brewed green or black tea.
Some brands contain such small amounts that consumers would have to drink 20 bottles to get the polyphenols present in one cup of home-brewed tea.
As lead author Shiming Li, Ph.D., said, “… 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.” (ACS 2010)
He pointed out that in addition to the low polyphenol content, bottled commercial tea delivers loads of sugar and the accompanying calories that consumers should be trying to avoid.
All six brands tested fell far short of brewed tea
Dr. Li and his colleagues measured the level of polyphenols in six brands of bottled tea beverages purchased from supermarkets. (The brands were not disclosed.)
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.
“Someone would have to drink bottle after bottle of these teas in some cases to receive health benefits,” he said. “I was surprised at the low polyphenol content. I didn’t expect it to be at such a low level.”
The six teas Li analyzed contained 81, 43, 40, 13, 4, or 3 milligrams (mg) of polyphenols per 16 oz. bottle.
In contrast, one average 5 oz. cup of home-brewed green or black tea, which costs only a few cents, contains 50 to 150mg of polyphenols.
Li said that some manufacturers do list polyphenol content on the bottle label.
But there are no uniform industry or government standards for measuring and listing the polyphenols in food or drink products, which leave ample room for mistakes and mischief.
A regular tea bag, for example, contains as much as 175mg of polyphenols, but they degrade over time as the tea is steeped in hot water.
Thus, the polyphenol content of bottled tea beverages will vary with the quantity and quality of tea used to prepare a batch and the tea brewing time.
“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 explained. “The simplest way is to add less tea, which makes the tea polyphenol content low, but tastes smoother and sweeter.”
While bottled teas are enjoyable beverages, brewed teas are more reliable for consumers looking to enjoy the health benefits as well as the taste of tea.
American Chemical Society (ACS). Bottled tea beverages may contain fewer polyphenols than brewed tea. August 22, 2010. Document available at http://portal.acs.org