Sunday, November 2, 2008

Dental Health Effects of Green and Black Tea

Chinese black tea is one way to prevent dental caries and bad breath. (Photo by ralphunden)

In my previous post, I summarized the studies on dental health and coenzyme Q10. This time I turn to the oral health effects of tea, as green tea extract is one of the ingredients in the toothpaste I'm currently testing.

Both green tea and black tea seem to be beneficial for teeth and gums, as is suggested by this study from 2001, which concludes that various components in tea, notably catechins, may have anti-cariogenic activity. According to the study, tea has a bactericidal effect against Streptococcus mutans, which is a bacteria commonly found in the oral cavity and a significant contributor to tooth decay. Tea also prevents bacterial adherence to teeth, limits the biosynthesis of sticky glucan, and inhibits amylases, which break starch down into sugar.

A study from 1998 concludes that green tea extracts strongly inhibited different kinds of bacteria. An earlier study showed that green tea extract increased the acid resistance of tooth enamel; the same effect was noticed even when fluoride was removed from the extract.

This study from 2006 studied the effects of epigallocatechin gallate (or EGCg), one of the catechins in green tea. The results suggest that EGCg is effective in reducing bacteria and acid production in dental plaque. Another study concludes that the catechins in green tea may reduce periodontal breakdown associated with periodontal disease.

Black tea is not without its oral benefits either. According to researchers at the University of Illinois at Chicago, polyphenols in black tea prevent the growth of bacteria responsible for bad breath. At higher concentrations the polyphenols apparently inhibited the growth completely, while at lower concentrations the growth was cut by 30 percent.

In this study, hamsters were fed either a regular diet or a cariogenic high-sucrose diet. When the hamsters in the two groups were given a standardized black tea extract instead of water, they had significantly lower caries formation. This effect was even more clear in the cariogenic diet group. Similar results were reported in another study, which concludes that consumption of black tea for two weeks attenuated the development and progression of caries in rats.

Like green tea, black tea works without the fluoride too, as this study from 1995 points out. The authors note, however, that when combined with fluoride, components such as tannin, catechin, caffeine and tocopherol had the best effect. The best combination was a solution of tannic acid and fluoride.

Together these studies strongly suggest that drinking tea, green or black, is helpful in preventing dental caries. However, as black tea stains teeth more than green tea does, it might be a good idea to choose green tea if you're concerned about teeth coloring. You might even consider white tea, which probably has a lot of the same effects of green tea and will likely stain the teeth even less, as it's not as dark in color as green or black tea.

For more information on green tea and black tea, see these posts:

Green Tea, Black Tea & Oolong Tea Increas Insulin Activity by More than 1500%
Drinking 10 Cups of Green Tea Daily and Not Smoking Could Add 12 Years to Your Life
Black Tea is More Effective in Reducing Superoxide Dismutase than Green Tea

Green Tea Reduces the Formation of AGEs

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