Tea
has turned out to be a double-barreled threat to tooth decay for
both the polyphenols (tannin) and the fluoride it contains.
Polyphenols tend to reduce the formation of plaque, while fluoride
strengthens tooth enamel so that it can resist decay. Some Chinese
and American researchers have concluded independently that two or
three cups a day, or, some say, only one of black tea, can decrease
tooth decay.
The
polyphenols bind themselves to mouth bacteria before the latter can
form plaque, according to Dr. Laurence E. Wolinsky, associate
professor of oral biology at the School of Dentistry of the
University of California at Los Angeles. He found an exceptionally
low rate of dental problems among people who drank a lot of tea.
Chinese researchers say that the human body consumes from one to
three milligrams of fluoride a day, enough for two cups of strong
tea, will replace this, according to their calculations. Green tea
contains twice as much fluoride as black, Dr. Sheldon Margen,
professor of Public Health Nutrition at the University of
California, wrote in the U.C. Berkeley Wellness Newsletter. Since
the mid-1940s, fluoride has been added to drinking water in many
communities in the United States and elsewhere. An analysis of the
fluoride content of teas sold in the United States found a range of
1.32 to 4.18 parts per million (ppm), according to a U.S. study.
Recommended fluoridation of water in the United States ranges from
0.7 ppm in warm areas, where more water is drunk, to 1.2 ppm.
Therefore anyone who drinks two cups a day of the highest ranking
tea would get 8.36 ppm per day, just a little less than someone who
drinks 8 glasses of fluoride content ought to do the trick. Chinese
researchers found that loose Gunpowder tea (a green tea) contains
100-150 ppm, 60 to 80 percents of which can be extracted.
While fluoridation of water is obviously desirable because it also
reaches children, who are not generally tea drinkers, the
information above should be good news for people who live in areas
without fluoridation, for by drinking tea they can derive the same
benefit. For sensitive teeth, a twice-daily rinsing of the mouth
with tea before swallowing it, if done over a long period of time,
is said to be effective.
