Tooth surface pH during drinking of black tea by A. Simpson, L. Shaw, and A. J. Smith Br Dent J 2001; 190: 374–376


Sugared and acid soft drinks have been implicated in causing dental caries and erosion. Unfortunately, they are popular, heavily advertised, and consumed in large quantities by adolescents in particular. Water is an excellent drink but has little 'street cred'. Milk is desirable from the nutritional viewpoint and is safe for teeth, as long as sugar is not added. Tea and coffee have also been recommended as satisfactory drinks from the dental viewpoint, again, as long as no sugar is added. There has been research on and off over 50 years on the anti-cariogenic properties of tea but, until now, we have been ignorant of the acidity of tea as drunk in this country and whether it is likely to erode teeth. This makes this paper, by experts on erosion from Birmingham Dental School, a valuable contribution to knowledge. It shows that although tea is acid, it is very weakly acid and contains only about 1% of the amount of citric acid found in fruit juice. They found that the fall in pH at the surface of teeth of young adult volunteers was small and brief, and unlikely to cause dental erosion. That is good news. It is possible to argue that these acids are chelators, which could remove calcium at more neutral pH. Other in-vitro experiments could test this, but it is unlikely that this is important. It is also worth noting that the pH profile in-vivo was not compared with any other drink, although one suspects that the extent and duration of the fall in pH would have been much greater with other acid soft drinks.

The authors rightly discuss what could be added to tea – milk, sugar or lemon. Milk would be desirable, sugar definitely not, and lemon might depend on the quantity. They also draw attention to the fact that tea reduces absorption of dietary iron. Iron is a risk nutrient for some groups in this country and more so in developing countries. Advice in these countries is often that young children should avoid drinking tea with meals – if so, unsugared tea with or without milk, would make a good, dentally safe, between meal drink for children.