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Tea and Oral Health


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Introduction

Dental disease remains a significant problem in the UK with a large number of the population suffering with the consequences of this disease at some stage in their lives. It can result in acute pain, aesthetic problems and can increase the risk of tooth loss, which may have long-term effects on food intake resulting in impaired nutritional status and subsequent overall well being.

Damage to or loss of teeth may result from:-

Dental Caries

Caries is caused by bacterial acid production in tooth plaque, which can cause deep localized lesions if it remains too near the tooth for any length of time. If left the bacteria then may penetrate the tooth further and progress into the soft pulp tissue. Untreated dental caries can lead to incapacitating pain, potential tooth loss and loss of dental function. The development and progression of dental caries is due to a number of factors, specifically bacteria in the dental plaque (particularly Streptococcus mutans) on susceptible tooth surfaces and the availability of fermentable carbohydrates.

The prevalence of dental decay in children in the UK has fallen significantly since the 1970’s mainly as a result of the introduction of fluoridated toothpaste and fluoridation of water supplies.[1] Nevertheless dental caries still remains a significant problem in some parts of the UK.

Acid Erosion

The damage to teeth from acid erosion is now thought to be a significant contributor to dental disease.[2] Erosion arises from acid derived from foods and drinks, or regurgitations from the stomach, which repeatedly wash over the teeth and result in shallower but more widespread lesions.

Periodontal Disease

Periodontal disease results from inflammation of the gum (gingivitis) that gradually causes destruction of the bone supporting the teeth. Gingivitis usually results from infection from debris that has accumulated at crevices at the base of the teeth.

Although the main reason for tooth extraction is as a result of dental caries, there appears to be an increasing trend for tooth loss in adulthood resulting from periodontal disease.[3]

Prevention of Dental Disease

Tea and Dental Health

Drinking tea (without added sugar) has been associated with a number of beneficial effects in preventing tooth decay.[6] Epidemiological surveys have reported that some populations who drink tea on a regular basis have a reduced number of carious teeth.[7],[8],[9] Proposed mechanisms for tea’s oral health benefits include:

1.    Fluoride

The tea plant (Camellia Sinensis) extracts fluoride from the soil, which then accumulates in its leaves. For this reason tea is a very rich natural source of fluoride; dry tea leaves may contain 4-400ppm fluoride, the brewed tea 0.34-6ppm[10],[11],[12],[13],[14],[15] resulting in one cup of tea containing between 0.3mg and 0.5mg of fluoride.

The Food Standards Agency Total Diet Study[16] conducted in 1997 showed that our fluoride intake is heavily influenced by tea consumption; beverages (mainly tea) account for 1mg/day or 85% of our total fluoride intake, excluding the contribution of fluoride in the water used to make the tea. When the water is from a fluoridated supply this approximately doubles the fluoride intake for consumers drinking 4 to 5 cups of tea per day. Consequently tea provides a good source of dietary fluoride.

Findings from a study that investigated the bio-availability of fluoride from tea in relation to its interaction with the tooth surface and oral tissues,[17] demonstrated that after rinsing with tea, 34% of the fluoride was retained in the oral cavity and that some of this showed a strong binding ability to enamel particles on the tooth surface. For this reason the authors concluded that tea was an effective vehicle for delivering fluoride to the oral cavity where it may then become associated with the oral tissues potentially helping to prevent dental decay.

Some concern has been raised over excessive intakes of fluoride causing fluorosis in the enamel of the teeth while it is still forming in children. Early signs of fluorosis are mottling and discoloration of the teeth. Although appearance of the teeth might be affected, there are no adverse effects to dental health. Reviews by expert panels have found no evidence that water fluoridation (at the optimal level for dental health) causes any adverse health effects.4,[18] Furthermore, the Dental profession is almost totally in favour of water fluoridation as a means of preventing tooth decay and any concerns have been carefully considered and discounted by the UK Public Health Alliance, The British Dental Association, The Faculty of Public Health and the British Fluoridation Society.[19]

2.    Tannins

Other components of tea may also contribute to the inhibition of caries. It has been reported that the tannins in tea can inhibit salivary amylase thereby reducing the cariogenic potential of starch-containing foods.[20] A number of studies have also demonstrated that tannic acid inhibits the growth of S.mutans bacteria,[21],[22],[23],[24],[25] a major factor in the build-up of dental plaque.

3.    Acid erosion

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.[26] Their effects increased dramatically when they were used in combination with fluoride.

The acid content of black tea and its influence on oral acidity during consumption has also been investigated.[27] The pH of the tooth surface in ten healthy volunteers was examined after consuming black tea. The very small, short-lived, pH decrease that was observed led to the conclusion that tea can be recommended as an alternative drink to the more acidic versions, such as fizzy drinks, as part of preventive measures for dental erosion.

  1. 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.[28],[29],[30] Extracts of green tea inhibit oral bacteria such as Esherichia coli, Streptococcus salivarius and Streptococcus mutans.[31]

Tea and Oral Cancer

It has been suggested that tea may play a role in the prevention of oral cancer.[32] One double-blind, randomised intervention trial suggested that treating patients with a mixture of black and green tea components could improve the clinical manifestations of precancerous oral lesions.[33]

Another study investigating the effect of tea as a chemopreventive agent in precancerous lesions (oral leukoplakia) has also found positive results. Eighty two subjects with oral leukoplakia received black tea in a fixed regimen for a year. Preliminary results on the first 15 patients who first entered the study have shown a clinical improvement.[34]

A pilot study showed that heavy smokers who consumed 5 cups of green tea a day for four weeks reduced the number of damaged cells in the mouth. The authors concluded that these results warrant a large scale intervention trial to further verify the role of green tea in the prevention of oral cancer in smokers.[35]

However, epidemiological evidence for oral cancer prevention has been sparse and inconclusive. For example, a population-based, case–control study in Denmark has found no association between tea consumption and the development of oral squamous cell cancer.[36]

In Summary…

There is a growing amount of in-vitro research identifying tea’s potential oral health benefits. However, further longer term, well controlled human trials are required before any firm conclusions can be made. In the mean time it is reasonable to conclude that drinking tea, without the addition of sugar, is compatible with dietary advice to prevent dental decay, thereby helping to promote overall health and well being.


References:

[1] Children’s dental health in the United Kingdom 2003. Office for National Statistics 2004

[2] British Nutrition Foundation (1999) Oral Health: Diet and other factors. London: BNF 1999

[3] Ong G (1998) Periodontal disease and tooth loss. International Dental Journal 48; (3 Suppl 1): 233-238

[4] McDonagh MS, et al (2000) A systematic review of public water fluoridation. York: The University of York NHS Centre for Reviews and Dissemination. Report 18

[5] Whitford GM. The metabolism and toxicity of fluoride. Basel: Karger 1996

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

[7] Ramsey AC, et al (1975) Fluoride intakes and caries increments in relation to tea consumption by British children. Caries Res 9; 312

[8] Onisi M (1985) Analysis of data obtained from 5 years tea drinking program for the caries prevention by means of the linear caries extent/ risk relation J. Dental Health 35; 138-9

[9] Cao J, et al (1987) Observation of caries incidence among a tea-drinking population. J Dental Health 31; 86-9

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

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

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

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

[14] 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.

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

[16] FSA, 1997 Total Diet Study - Fluorine, Bromine and Iodine. 2000, FSA Surveillance Unit.

[17] Simpson A, et al (2001) The bio-availability of fluoride from black tea. J Dentistry 29; 15-21

[18] Medical Research Council (2002) Working Group Report: Water Fluoridation and Health. MRC. London

[19] One in a Million – the facts about water fluoridation. 2nd edition. (2004) Published by: The British Fluoridation Society, The UK Public Health Association, The British Dental Association, and The Faculty of Public Health

[20] Zhang J, et al (1998) Inhibition of salivary amylase by black and green teas and their effects on the intraoral hydrolysis of starch. Caries Research 32; 233-8

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

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

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

[24] 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

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

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

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

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

[29] 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

[30] 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.

[31] Rasheed A, Haider M (1998) Antibacterial activity of Camellia sinensis extracts against dental caries. Arch Pharm Res 21; 348-352

[32] Yang C. S., Maliakal P., Meng X. (2002) Inhibition of carcinogenesis by tea. Annu. Rev. Pharmacol. Toxicol. 42; 25-54

[33] Li N, et al (1999) The Chemopreventive Effects of Tea on Human Oral Precancerous Mucosa Lesions. Proceedings of the Society for Experimental Biology and Medicine; 220

[34] Halder A, et al (2005) Black tea (Camellia sinensis) as a chemopreventive agent in oral precancerous lesions. J Envir Path Toxicol Oncol 24; 141-4

[35] Schwartz JL, et al (2005) Molecular and cellular effects of green tea on oral cells of smokers: a pilot study. Mol Nutr Food Res 49; 43-51

[36] Bundgaard T., Wildt J., Frydenberg M., Elbrond O., Nielsen J. E. (1995) Case-control study of squamous cell cancer of the oral cavity in Denmark. Cancer Causes Control 6; 57-67

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