Sir, we read with interest the recent article by Nadimi et al.1 The authors reviewed studies regarding sugar-free products and dental caries or dental erosion and raise a concern about sugar-free confections and dental erosion.

As stated in the paper by Nadimi et al., 'polyol-based sugar-free products may decrease dental caries incidence.' What the authors failed to make clear is that the erosive potential of sugar-free confections actually is derived from acidic ingredients, which may be used in sugar-free products independent from polyols; these ingredients, not the polyols, directly create an acidic pH at the tooth surface.

Polyols are safe for consumption and it is well documented that they provide health and dental benefits. For example, polyols used to replace sugar in sugar-free products can help reduce overall sugar intake, diminish blood glucose response, reduce caloric intake, and lead to improved dental health. Scientists and regulators alike recognise that polyols do not cause tooth decay and labelling indicating this health benefit is allowed in the US and the European Union as well as many other parts of the world.

Further, polyols can be used to replace sugar for various reasons, but not all sugar-free products are intended to be tooth-friendly. In tooth-friendly products, polyols replace fermentable carbohydrates (sugars) in order to reduce fermentation activity and the resulting acidic pH at the tooth surface. It is possible to successfully develop sugar-free confections with tooth-friendly properties, as shown by the large range of product examples in the marketplace. Those products can be identified by a tooth-friendly claim, in addition to the sugar-free claim.

Current research indicates that individual susceptibility to tooth erosion varies depending on one's behaviour, lifestyle, diet and genetic make-up. It is impossible to single out any one food or beverage as the cause of dental erosion considering the many factors that determine individual dental health, including the types of food consumed, the length of time foods stay in the mouth, the level of oral hygiene, and access to professional dental care.

Corresponding author Sok-Ja Janket responds: In response to Dr Stevens' letter regarding our article 1 I would like to respond on behalf of my team. Contrary to Dr Stevens' allegations, we have clearly stated that sugar-free products might pose dental erosion risk 'if they contain acidic flavouring' several times in the article. Moreover, we have highlighted all the studies that have shown dental health benefits of polyols on the second and third pages. 1 We further clarified in non-scientific media that it is the acidic flavouring, not the polyols, that causes the harm. The following are links to some of the interviews we have given.

Dentistry IQ http://bit.ly/qowuP2

Sydney Morning Herald http://www.smh.com.au/lifestyle/diet-and-fitness/the-sugarfree-myth-20111019-1m6z5.html

Beveragedaily.com http://www.beveragedaily.com/Formulation/Sugar-free-drinks-may-generate-false-security-on-tooth-decay-study-finds

The long term safety of polyols on general health appears to be unknown. We would like to inform readers that the European Union has banned the use of polyols in beverages according to a non-scientific medium which can be accessed via the following link. http://www.beveragedaily.com/Formulation/Sugar-free-drinks-may-generate-false-security-on-tooth-decay-study-finds

If Dr Stevens wishes to claim long term safety of polyols, she should provide references. For a person who works for an organisation promoting low calorie products, her opinion may not be impartial. This clear conflict of interest gives her comments very little credibility. A renowned diabetes researcher, Dr Bloomgarden, stated that direct testing to rule out human toxicity was not required for FDA approval (for nutriceuticals such as polyols), unlike the approach taken with pharmaceutical products. 2 Furthermore, Dr Stevens' claim that 'polyols reduce caloric intake' may not be entirely correct, because diet soda drinkers did not lose weight and the sweet taste actually increased the appetite. 3, 4

As Stevens correctly stated, polyols substitute for fermentable carbohydrates in an attempt to reduce acid production by microbiota and thus decrease subsequent dental caries. However, some sugar-free products with acidic additives deliver acids directly to tooth surfaces which polyols were intended to reduce. So, what is the purpose of using sugar-free products? We encourage the artificial sweetener industry to prove long term safety by a randomised trial, not an epidemiologic study which is prone to biases. Our group is qualified to conduct such studies and has a proven history of not being swayed by outside pressures or established dogma. 5

Lastly, all the studies we have reviewed were intervention studies in the format of in vitro or ex vivo, thus 'one's behaviour, lifestyle, diet, genetic make-up, oral hygiene, and access to professional dental care' could not have affected the results. In addition, there is overwhelming evidence that industrial exposure to acid fumes causes dental erosion.6,7 Therefore, it is transparent that exposure to acids is a risk factor for dental erosion.8,9

In conclusion, we do not discount the benefits of polyols on dental caries but acidic additives should be avoided and long term safety of polyols should be studied in humans. The objective of our review was to raise awareness of the risk hidden under the false security of 'sugar-free' dental health claims.