August 13/Islamabad, Pakistan/Right Vision News -- A new research has shown that black tea contains higher concentrations of fluoride than previously thought. The additional fluoride from drinking two to four cups of tea a day will not harm anyone; it is the very heavy tea drinkers who could get in trouble, BBC reported.

Most published reports show 1-5mg of fluoride per liter of black tea, but the new study shows that number could be as high as 9mg.

Fluoride is known to help prevent dental cavities, but long-term ingestion of excessive amounts could cause bone problems.

The researchers found that the fluoride concentration in black tea had long been underestimated when they 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 tea brands of the patients were tested for fluoride concentrations, and it was found that fluoride concentrations was low, noting that the tea plant, Camellia sinensis, creates a quandary when measuring fluoride. Unique among other plants, it accumulates huge concentrations of fluoride and aluminium in its leaves. When the leaves are brewed for tea, some of the minerals leach into the beverage.

From the August 30, 2010, Prepared Foods E-dition