Summary of: An in vitro investigation of the erosive potential of smoothies. Commentary

Acidic drinks have long been recognised as an important extrinsic factor for the development of dental erosion. A high soft drink consumption is considered the major cause of the high prevalence of erosive wear in the younger population factor. However, it has been shown that besides soft drinks, a number of other frequently consumed acid-containing food products, such as sport drinks, energy drinks and acidic candy, have considerable erosive potential. In the present study, the authors demonstrate that fruit smoothies should be added to this growing list.

Fruit smoothies are generally made only from pure fruits blended with 100% pure fruit juice. Therefore, they are considered healthy and several organisations have advocated the consumption of fruit smoothies. As a result, the consumption has risen dramatically. In the UK, the consumption increases 50% annually and currently 60% of the British parents give their children fruit smoothies.

Considering the erosive potential of fruit smoothies their consumption gives cause for concern, especially with regard to children. Deciduous enamel seems more sensitive to erosion by low pH drinks,² especially with increased frequency of consumption. In addition, exposure to acidic drinks at an early age may influence food preferences, which may lead to an increased consumption of acidic foods later in life.³ In addition to containing high amounts of acids, such as citric and malic acid, fruit smoothies also contain high levels of carbohydrate, which increases the risk of developing caries.

The smoothies investigated in the present study had pH values between 5.1 and 5.4. These values are only slightly lower than the pH value of 5.5, generally considered the critical value below which enamel dissolves. Despite their relatively high pH values, immersion of extracted teeth in smoothies induced significant reductions in surface micro-hardness and induced loss of enamel as determined by profilometry. This may be related to the high titratable acidity of smoothies, which is much higher than the titratable acidity of non-fruit carbonated soft drinks.

Fruit smoothies may have beneficial effects on general health, being a source of vitamins and other important nutrients. However, in view of their erosive and cariogenic potential, frequent consumption of smoothies should be discouraged. Therefore, the authors recommend that their consumption should be confined to mealtimes.