Whilst tea is often associated with staining teeth, many studies have shown that tea (when drunk with no added sugar) can prevent tooth decay.[i]

This is due to the composition of the tea leaf, with the following 'ingredients' playing a key role:

Fluoride

Tea leaves are a rich source of fluoride, which the tea plant extracts from flouride in the soil when growing. Dry tea leaves may contain 4-400ppm fluoride, and brewed tea 0.34-6ppm[v],[vi],[vii],[viii],[ix],[x] resulting in one cup of tea containing between 0.3mg and 0.5mg of fluoride.

Tannins

A number of studies have demonstrated that tannic acid inhibits the growth of S.mutans bacteria,[xvi],[xvii],[xviii],[xix],[xx] a major factor in the build-up of dental plaque.

In addition to its beneficial effect on plaque, tannin, along with other components of tea such as catechin, caffeine and tocopherol have been shown to be effective in increasing the acid resistance of tooth enamel.[xxi]

Flavonoids

Both green and black tea and their specific flavonoids, mainly catechins, have exhibited inhibitory effects on the growth of cariogenic bacteria by preventing the adherence and growth of plaque bacteria at the tooth surface.[xxiii],[xxiv],[xxv]

Extracts of green tea inhibit oral bacteria such as Esherichia coli, Streptococcus salivarius and Streptococcus mutans.[xxvi]

References

[i] Hamilton-Miller J. M. (2001) Anti-cariogenic properties of tea (Camellia sinensis). J. Med. Microbiol., 50: 299-302

[ii] Cremer HD, et al (1970) Absorption of fluorides, Fluoride and human health. Geneva: WHO, 75-91

[iii] Wei SHY, et al (1989) Concentration of fluoride and selected other elements in tea. Nutrition 5; 237-40

[vii] Chan JT, et al (1996) Fluoride content in caffeinated, decaffeinated and herbal teas. Caries Research 30; 88-92

[iv] Hayacibara MF, et al (2004) Fluoride and aluminium in teas and tea-based beverages. Rev Saude Publica 38; 100-5

[v] Jenkins, G.N., (1991) Fluoride intake and its safety among heavy tea drinkers in a British fluoridated city. Proc Finn Dent Soc, 87(4): 571-9.

[vi] Clovis, J. and J.A. Hargreaves, (1988) Fluoride intake from beverage consumption. Community Dent Oral Epidemiol,. 16; 11-5.

[vii] Iizuka S. (1980) Inhibitory effect of tannic acid on the lactate metabolism in human saliva. Dentistry 67; 770-778

[xvii] Paolino VJ, et al (1980) Inhibition of dextran synthesis by tannic acid. Am Assoc Dent Res; 488 (abstract)

[viii] Wu-Yuan CD, et al (1988) Gallotannins inhibit growth, water insoluble glucan synthesis and aggregation of mutans streptococci. J Dent Res 67; 51-55

[viiii] Tachibana Y, et al (1989) The effect of suppression of the tannin fluoride preparation upon the development of dental plaque. J Jpn Endodont 10; 60-65

[x] Itoh T (1991) Inhibition of cariogenic factor of mutans streptococci by tannic acid. Nihon Univ J Oral Sci17; 115-126

[xxi] Yu H, et al (1995) Effects of several tea components on acid resistance of human tooth enamel. J Dent 23; 101-105

[xi] Simpson A, et al (2001) Tooth Surface pH during drinking of black tea. British Dental Journal 190; 374-376

[xii] Otake S, et al (1991) Anticaries effects of polyphenolic compounds from Japanese green tea. Caries Res, 25(6); 438-43

[xiii] Sakanaka S, et al (1990) Inhibitory effects of green tea polyphenols on glucan synthesis and cellular adherence of cariogenic Streptococci. Agric Biol Chem 54; 2925-9

[xiv] G.X. Wei and C.D. Wu , (2001) Black tea extract and polyphenols inhibit growth and virulence factors of periodontal pathogens. J Dent Res 80; 73.