BBC Tuesday, 22 May, 2001, 23:21 GMT 00:21 UK

Tea 'good for teeth'

Scientists believe that drinking tea may be a good way to keep your teeth healthy.

They have discovered that compounds found in black tea may attack harmful bacteria in the mouth that cause gum disease and cavities.

Researchers have previously focused on the possible health benefits of green teas.

But a team from the University of Illinois College of Dentistry studied the black teas more commonly consumed in the West.

They found that compounds in black tea were capable of killing or suppressing growth and acid production of cavity-causing bacteria in dental plaque.

Enzyme

Black tea also affects the bacterial enzyme glucosyltranferase which is responsible for converting sugars into the sticky matrix material that plaque uses to adhere to teeth.

In addition, certain plaque bacteria, upon exposure to black tea, lost their ability to form the clumpy aggregates with other bacteria in plaque, thereby reducing the total mass of the dental plaque.

One experiment showed that when volunteers rinsed with black tea for 30 seconds five times at three-minute intervals, plaque bacteria stopped growing and producing acid, which breaks down the teeth and causes cavities.

Lead researcher Dr Christina Wu said the research indicated that black tea could have a "significant" impact on dental health.

However, she warned that the beneficial effect was dependent on people taking good care of their teeth in other ways.

'Good alternative'

The British Dental Association said both black and green tea could help to combat the build-up of plaque.

A spokesperson said: "Dentists also feel that drinks such as tea are a good alternative to soft drinks since tea is non-erosive."

Dental erosion involves demineralisation where teeth are attacked by acids and tooth enamel is consequently worn away.

It can be extremely painful, especially if it is extensive enough to wear through the enamel and expose the dentine and tooth pulp underneath.

The BDA spokesperson said that tea was also a good source of fluoride which can help to protect the teeth.

A spokesperson for the British Dental Health Foundation agreed, but pointed out that only 10-11% of the UK's tap water is currently fluoridated.

He said that as 98% of people take their tea with milk, it also provided a good source of calcium.

"However, it still remains to be demonstrated whether the benefits observed in the research are replicated during normal tea drinking," he added.

The research was presented at the American Society for Microbiology in Orlando, Florida.

-- Anonymous, May 23, 2001