Black Tea Has More Fluoride Than Once Thought

AUGUSTA, Ga.Along with polyphenols and great taste, black tea drinkers may be getting a higher dose of fluoride than previously thought, according to new research. The findings from the Medical College of Georgia suggest black tea could pose potential health risks to those who drink more than four cups a day.

Previous published studies show black tea contains 1 to 5 milligrams of fluoride per liter, but this new study found it could have as high as 9 milligrams per liter.

According to a press release from the Medical College of Georgia, most published studies about black tea have used a method of measuring fluoride that doesnt account for the amount that combines with aluminum to form insoluble aluminum fluoride. Dr. Gary Whitford, Regents Professor of oral biology in the School of Dentistry, compared that method with a diffusion method, which breaks the aluminum-fluoride bond so that all fluoride in the tea samples can be extracted and measured.

Whitford tested seven brands of store-bought black tea, steeping each for five minutes in deionized water, which contains no fluoride. The amount of fluoride in each sample was 1.4 to 3.3 times higher using the diffusion method than the traditional method.

Whitford discovered that the fluoride concentration in black tea had long been underestimated when he began analyzing data from four patients with advanced skeletal fluorosis, a disease caused by excessive fluoride consumption and characterized by joint and bone pain and damage. The common link between these four patients was their tea consumption each person drank 1 to 2 gallons of tea daily for the past 10 to 30 years.

Low-doses of fluoride (about 2 to 3 milligrams a day) are known to help dental health, but long-term ingestion of excessive amounts of 20 milligrams a day over 10 or more years may cause bone problems.

Whitford presented his findings at the 2010 International Association of Dental Research Conference in Barcelona, Spain.