The Acidic and Erosive Potential of Five Sports Drinks

Sports drinks are becoming increasingly popular as we are all being encouraged to adopt a healthier lifestyle with regular exercise. However, many of these products are based on acidic fruits and may contribute to erosion. The aim of this study was to screen a number of these products for their potential to cause enamel erosion in vitro. The erosive potential of a number of readily available sports drinks was assessed in the laboratory by measuring their pH, neutralisable acidity and their ability to erode enamel. These were compared to a positive control, orange juice and a negative control, water. The pH of the sports drinks ranged from 3.16– 3.70 with their neutralisable acidity ranging from 9.74–13.44 mls of 0.1M NaOH. The amount of enamel removed following 1-hour immersion in the sports drinks ranged from 1.18–5.36 microns. In comparison, the orange juice control had a pH of 3.68, a neutralisable acidity of 19.68 mls of 0.1 M NaOH and removed 3.24 microns of enamel. Many of the sports drinks tested were found to be erosive. This information will be of use to clinicians when counselling patients with tooth surface loss who use fruit based sports drinks regularly. KEY WORDS: Dental erosion, dental enamel, non-carious tooth surface loss

Dental erosion is defined as an irreversible loss of dental hard tissues due to a chemical process without the involvement of microorganisms1. This process may be caused by extrinsic or intrinsic agents. Extrinsic agents include acidic food stuffs, beverages and snacks consumed as part of the daily diet. Extrinsic erosion may also occur following environmental exposure to acidic agents2,3. Intrinsic causes are associated with gastric acid and may present intra-orally following vomiting, regurgitation, gastro-oesophageal reflux or rumination4. The popular literature and media extol the virtues of a healthy lifestyle. Regular exercise and a healthy diet are being endorsed by central government in an attempt to prevent obesity and life threatening diseases such as diabetes and heart disease. Strenuous exercise quickly results in dehydration and depletion of energy stores which can lead to reduced physical and mental performance. Although these effects can be combated by the regular ingestion of water both during and after exercise, there is some evidence to show that commercially available sports drinks are more effective than water at maintaining optimal performance levels and augment recovery following exercise5,6. Sports drinks are essentially water based but also contain carbohydrates as a ready energy source, electrolytes that replace lost ions and B group vitamins that help release energy6. They are also isotonic; this encourages rapid absorption once ingested. However, all these drinks are based on natural fruits and therefore may have an erosive potential.

Sports drink use amongst athletes is very common, with over 90% of athletes using these products on a regular basis7. These products are also advertised aggressively by the manufacturers’ and their use is publicly endorsed by many famous elite athletes. However, the link between the consumption of sports drinks and erosion amongst athletes is still rather tenuous. Some case reports have suggested a relationship between sports drinks consumption and erosion8–11 and Milosevic12 has demonstrated an association between erosion and sports drink consumption. However, Mathew et al7 examined a group of over 300 University based athletes in the United States, but could not show a statistically significant association between erosion and the use of sports drinks. One explanation for this is that sports drinks often have a low viscosity12 and are likely to be cleared quickly from the mouth. The aim of this study was to compare a number of commercially available sports drinks and compare these with water and orange juice. The hypothesis used in this study was that the sports drinks would not be more erosive than orange juice.

The sports drinks chosen for inclusion in this study are listed in Table 1. These drinks were chosen as they were readily available to the public at a major supermarket. Other sports drinks are powder based requiring the addition of water and therefore the sample tested here may not be totally representative of all sports drinks.

Initial pH * BDS, MScD, FDSRCS (Ed), PhD, ILTM † IBMS # BDS, MScD, FDSRCS, FDS (Rest Dent), DRD, MRD RCS (Ed), ILTM

The pH of each of the drinks was tested using an electronic pH meter (Orion Research Inc.) at 37°C on a heated magnetic stirrer. The pH meter was calibrated using test