Instant iced tea mixes may contain potentially harmful levels of fluoride (search), according to a new study.
Researchers found some commercial iced tea mixes contain up to 6.5 parts per million (ppm) of fluoride, which is well above the 4 ppm maximum allowed by the EPA in drinking water and 2.4 ppm permitted by the FDA in bottled water and beverages.
The results indicate constantly quenching your thirst with instant iced teas may increase your risk of a rare, but potentially dangerous bone disorder caused by getting too much fluoride in your system.
When fluoride levels are too high, it causes bone-forming cells to produce more skeletal tissue (search), which increases bone density but also bone brittleness. The condition leads to a disease called skeletal fluorosis (search) and may result in bone pain, stiffening of ligaments, bone spurs (search), fused vertebrae (search), and difficulty in moving joints.
"When fluoride gets into your bones, it stays there for years, and there is no established treatment for skeletal fluorosis," says researcher Michael Whyte, MD, professor of medicine, pediatrics, and genetics at Washington University School of Medicine in St. Louis, in a news release. "No one knows if you can fully recover from it."
"The tea plant is known to accumulate fluoride from the soil and water. Our study points to the need for further investigation of the fluoride content of teas," says Whyte. "We don’t know how much variation there is from brand to brand and year to year."
Iced Teas May Have Too Much Fluoride
Researchers analyzed the fluoride content of commercial instant tea mixes after diagnosing a middle-aged woman with spinal pain caused by extremely dense bones. Tests showed that the woman had high levels of fluoride in her urine.
The woman said she drank 1 to 2 gallons of double-strength instant tea throughout the day, which prompted researchers to test for fluoride content in several brands of instant iced tea mixes available in grocery stores.
They sent 10 samples of iced tea mixes to two different independent laboratories in St. Louis for testing. The teas were prepared on two separate occasions using distilled water.
The results appear in the January issue of The American Journal of Medicine.
Their analysis showed that the fluoride content of the instant tea mixes varied from 1.0 ppm to a high of 6.5 ppm. The results of the tests for each brand appear below:
Researchers say that daily consumption of 3 milligrams of fluoride for women and 4 milligrams for men is considered enough to prevent tooth decay.
In many communities, fluoride is added to drinking water for this purpose. But researchers say the Public Health Service indicates that the fluoride concentration in water should not exceed 1.2 ppm.
Typically adults consume less than 1 milligram of fluoride per day in their food. Fluorinated water increases intake by about 1 milligram per day.
According to the researchers it would take at least 10 milligrams of fluoride daily for 10 years to begin to show signs of fluorosis on bone x-rays.
Americans are also exposed to fluoride from other sources, such as fluorinated toothpastes and other dental products. More unusual fluoride sources include pesticides, Teflon-coated cookware, chewing tobacco, and some wines and mineral waters.
But researchers say that until now instant iced tea mixes have not been recognized as potential sources of fluoride in people’s diets. They say their findings indicate that doctors should ask people who complain about bone aches and pains about how much tea they drink in order to rule out skeletal fluorosis.
In the case of their patient, researchers say the pain gradually went away over several years after she stopped drinking instant tea.
SOURCES: Whyte, M. The American Journal of Medicine, January 2005; vol 118: pp 78-82. News release, Washington University School of Medicine, St. Louis.